: 2001 ETC Intermittent High Idle



ontarff
11-17-13, 01:55 PM
I experienced and seemed to have resolved an intermittent high idle problem. Occasionally the idle speed does't fall below 1200 rpm or higher causing a high coolant temperature. No DTC. I removed the idle air control (IAC) valve. It had a lot of soot on it. I cleaned the plunger, shaft and hole where it was mounted thoroughly with carburetor cleaner. I also cleaned the throttle body that wasn't too dirty. I wanted to replace the throttle position sensor (TPS), no DTC, but couldn't get to the retaining screws with a screw driver!

Does anyone know how to remove the two Phillip's head retaining screws on the TPS? There is not enough clearance for a 90 degree screw driver to fit between the screw and a thick metal piece where the coolant crossover is mounted. The repair manual does not explain how to get to the screws other than removing the water pump belt cover.

Ranger
11-17-13, 02:46 PM
You'll probably have to remove the TB, but Usually the TB is the culprit. Hard to imagine it was clean, but the IAC valve wasn't.

LloydCFerguson
11-17-13, 03:56 PM
I've found that servicing things on the drivers side of the engine usually requires removing other parts, that is just the way these cars are. Removing the waterpump belt cover is not that difficult and gives you the chance to check the belt and tensioner while you are in there.

basscatt
11-17-13, 04:04 PM
I experienced and seemed to have resolved an intermittent high idle problem. Occasionally the idle speed does't fall below 1200 rpm or higher causing a high coolant temperature. No DTC. I removed the idle air control (IAC) valve. It had a lot of soot on it. I cleaned the plunger, shaft and hole where it was mounted thoroughly with carburetor cleaner. I also cleaned the throttle body that wasn't too dirty. I wanted to replace the throttle position sensor (TPS), no DTC, but couldn't get to the retaining screws with a screw driver!

Does anyone know how to remove the two Phillip's head retaining screws on the TPS? There is not enough clearance for a 90 degree screw driver to fit between the screw and a thick metal piece where the coolant crossover is mounted. The repair manual does not explain how to get to the screws other than removing the water pump belt cover.
--------------------------------
I wanted to replace the throttle position sensor (TPS),
no DTC, but couldn't get to the retaining screws with a screw driver!
ASSUMING you pulled the codes correctly -
if the TPS was defective - or not responding - or out of range -
a code would be set -

throwing parts at the car is RARELY the answer -
and is definitely the most expensive method of repair -

ontarff
12-30-13, 07:42 PM
OK, I removed the throttle body to get to the TPS. I replaced the TPS. I was driving home today and AGAIN got a high idle problem. I don't know how to solve the problem now. I cleaned the thottle body, replaced the TPS and IAC and the problem still exists. Please advise

basscatt
12-31-13, 01:44 PM
OK, I removed the throttle body to get to the TPS. I replaced the TPS. I was driving home today and AGAIN got a high idle problem. I don't know how to solve the problem now. I cleaned the thottle body, replaced the TPS and IAC and the problem still exists. Please advise
-------------------------
ASSUMING you checked that the gas pedal is not hanging up on the floor mat -
and the throttle cable itself is not binding somewhere -
and the throttle plate is not binding on anything -

step #1 is ALWAYS check for Diagnostic Trouble Codes -

if you don't know how - go here and read the ENTIRE post -

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/138257-how-pull-codes-dtcs.html

if you have any codes - post them here -
ALONG WITH THEIR DEFINITIONS -
------------------

2kflhr
12-31-13, 08:54 PM
OK, I removed the throttle body to get to the TPS. I replaced the TPS. I was driving home today and AGAIN got a high idle problem. I don't know how to solve the problem now. I cleaned the thottle body, replaced the TPS and IAC and the problem still exists. Please advise Are the throttle cable connection points lubricated?

ontarff
12-31-13, 10:35 PM
-------------------------
ASSUMING you checked that the gas pedal is not hanging up on the floor mat -
and the throttle cable itself is not binding somewhere -
and the throttle plate is not binding on anything -

step #1 is ALWAYS check for Diagnostic Trouble Codes

if you don't know how - go here and read the ENTIRE post -

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/138257-how-pull-codes-dtcs.html

if you have any codes - post them here -
ALONG WITH THEIR DEFINITIONS -
------------------

No DTCs, Problem occurs after a warm restart and engine comes up to normal operating temperature (at twelve o'clock).

ontarff
12-31-13, 10:40 PM
I haven't lubed them. I will and advise (with my fingers crossed!).

ontarff
01-01-14, 04:37 PM
I lubed the throttle cable attachment point and where the spring rubs next to the pulley. Could it be something wrong with the computer?

basscatt
01-01-14, 06:12 PM
I lubed the throttle cable attachment point and where the spring rubs next to the pulley. Could it be something wrong with the computer?
---------------------
Could it be something wrong with the computer?
a computer or sensor malfunction should set a fault code -

ontarff
01-01-14, 06:51 PM
2001 ETC with 69,000 miles. - I am having an intermittent high idle problem on a warm restart. Sometimes the idle RPM will not go back down below 1100. This causes a high coolant temp. (1-2 ticks). I cleaned the throttle body (not very dirty), throttle plate and replaced the IAC first, then installed a new TPS. Problem still occurs. Could it be the ECU? I noticed that since I replaced the TPS, on a cold start, initial RPM is 1100 for about 20 seconds and then drops to 900 but hunts a little between 850-950 when I put it in gear (R or D). 650 RPM when up to normal temp (gauge just a little past 12 o'clock). No coolant leaks, no DTCs.

ontarff
01-01-14, 06:57 PM
---------------------
Could it be something wrong with the computer?
a computer or sensor malfunction should set a fault code -

No DTCs.

Submariner409
01-02-14, 09:04 AM
Your cold start fast idle sequence is correct, but not the "hunting" during the 900 rpm part.

Vacuum leak ? An EVAP problem (vacuum leak) would set an emissions (P) code. Clean the IAC plunger ? I doubt the PCM is at fault.

Even a high idle, if left alone for a few minutes (HVAC off), would cause the fans to turn on at 224 degrees - just less than one tick past the center position on the gauge. The engine then cools to 214, fans shut off, and the cycle begins. If the HVAC (A/C compressor operation set) was on, then fans run in SLOW all the time, so the engine should not heat much past the center mark, if at all.

Study the stickys just above this thread - fans, gauges, cooling system operation.

JoeTahoe
01-02-14, 11:24 AM
any engine codes. could be intake plenum is dry rotted and leaking

ontarff
01-02-14, 10:08 PM
Car ran well today, no high idle on 3 warm restarts.

ontarff
01-08-14, 10:32 PM
any engine codes. could be intake plenum is dry rotted and leaking

No DTCs. Intake manifold plenum replaced 11/24/2010 @ 52, 798 mi. Current mileage @ 69, 650. Engine ran fine at normal idle on short trips (less than 10 miles). Engine had unstable high idle (1100 rpm) again today returning from a 60 mile trip after warm restart. Engine ran warmer than usual (1 tick past 12 o'clock). I pulled over and turned engine off, waited 15 seconds and restarted. Idle normal (690 rpm). Raised and lowered rpm in PARK, no idle change. Placed in DRIVE and high idle (1100 rpm) started again after car began moving at 25 mph. No codes. After returning home with high idle problem I let the engine cool. I restartrted and noticed when rpm dropped to 900 after 25 seconds it began hunting soon after between 650-750 rpm. The hunting reduced to about 50 rpm after I let the car idle for about 10 minutes. It settled down and stabilized around normal warm idle at 690. Is there a learning curve for the computer after replacing both the ISC and TPS? It is inconsistent. I am concerned the higher engine temps associated with the intermittent high idle is not good for the head gaskets, let alone the brakes.

Engine ran fine for a few days at normal idle on short trips (less than 10 miles). Today engine had unstable high idle (1100 rpm) returning from a 60 mile trip after warm restart. Engine ran warmer than usual (1 tick past 12 o'clock). I pulled over and turned engine off, waited 15 seconds and restarted. Idle normal (690 rpm). Raised and lowered rpm in PARK, no idle change. Placed in DRIVE and high idle (1100 rpm) started again after car began moving at 25 mph. No codes. After returning home with high idle problem I let the engine cool. I restartrted and noticed when rpm dropped to 900 after 25 seconds it began hunting soon after between 650-750 rpm. The hunting reduced to about 50 rpm after I let the car idle for about 10 minutes. It settled down and stabilized around normal warm idle at 690. Is there a learning curve for the computer after replacing both the ISC and TPS? It is inconsistent. I am concerned the higher engine temps associated with the intermittent high idle is not good for the head gaskets, let alone the brakes.

Submariner409
01-09-14, 07:59 AM
A slightly high idle has exactly nothing to do with head gaskets. Elevated temperatures have nothing to do with head gaskets.

High idle makes it a bit harder to stop the car, so yes, it might increase front pad wear a tiny bit.

I merged the posts from your identical thread down in Engines, Northstar. Please keep all questions and info on the same car/problem in one thread. If you feel that this engine idle problem would gather more responses in Engines, the entire thread can be moved there.

ontarff
01-12-14, 04:21 PM
The intermittent high idle problem still exists after a warm restart. Are we out of solutions? I didn't think this would be rocket science.

1) Throttle body and throttle plate cleaned.
2) Replaced IAC.
3) Replaced TPS.
4) No DTCs.
5) No binding on throttle cable.
6) Air filter replaced.
7) Oil and filter changed.

ontarff
01-17-14, 10:14 PM
High idle (1100 rpm) problem reoccurred again today on the last 2 miles of a 20 mile drive home after the car sat and cooled for 5 hours. Should I replace any more parts?

ontarff
01-18-14, 12:49 AM
A slightly high idle has exactly nothing to do with head gaskets. Elevated temperatures have nothing to do with head gaskets.

High idle makes it a bit harder to stop the car, so yes, it might increase front pad wear a tiny bit.

I merged the posts from your identical thread down in Engines, Northstar. Please keep all questions and info on the same car/problem in one thread. If you feel that this engine idle problem would gather more responses in Engines, the entire thread can be moved there.

Maybe we could get some more answers in the Northstar forum.

basscatt
01-18-14, 01:14 AM
Maybe we could get some more answers in the Northstar forum.
--------------------
you keep saying no codes - and that simply doesn't make sense -

what method are you using to pull codes?

ontarff
01-19-14, 12:18 AM
--------------------
you keep saying no codes - and that simply doesn't make sense -

what method are you using to pull codes?

OFF + passenger warmer buttons w/key on.

No PCM, IPC, ACM, SDM, TCS, RSS, PZM, IRC, RFA, OCP, MSM or MMM codes.

I know it doesn't make sense, that is a big part of the problem.

MoistCabbage
01-19-14, 08:21 AM
Grasping at straws, but I'd probably try disconnecting the cruise control servo, just for the hell of it.

ontarff
01-21-14, 12:17 AM
Today it ran fine to the golf course and back until the last mile (driving on an uphill grade) of a 25 mile return trip home. High idle (1100 rpm) kicked in while slowing to make a left turn 1 block from my home.

ontarff
01-25-14, 07:07 PM
Moderator, can we move this thread to the Northstar forum? I need more answers to resolve this idle problem.

Ranger
01-25-14, 08:36 PM
Same guys are going to answer you there, but I'll move it for you.

MoistCabbage
01-25-14, 08:37 PM
:yeah:

ontarff
01-26-14, 10:25 AM
Thanks, it acted up again yesterday coming back home from the golf course 25 miles away after it sat for 4.5 hours. I am very frustrated with this problem that can't be fixed.

Submariner409
01-26-14, 10:44 AM
With the key off, reach down to the gas pedal and operate it with your hand - all the way to wide open and back - any jerky or sticky feeling ?

If that throttle cable has a slight kink, burr or is lacking lubrication it might be sticking somewhere ..............

Gas pedal free and clear of the carpet/mat ?

ontarff
01-26-14, 08:26 PM
With the key off, reach down to the gas pedal and operate it with your hand - all the way to wide open and back - any jerky or sticky feeling ?

If that throttle cable has a slight kink, burr or is lacking lubrication it might be sticking somewhere ..............

Gas pedal free and clear of the carpet/mat ?

No jerky or sticky feeling depressing the accelerator pedal. The floor mat is not a factor. The problem only occurs after a warm restart. When the car is started cold, driven less than 10 miles and restarted for a return trip, no problem.

It seems that the problem is associated with engine (not coolant) temperature when the transmission is operating. If the engine is warm and the car is turned off and restarted the idle returns to normal until the accelerator pedal is depressed when the car is in DRIVE.

Ranger
01-26-14, 08:54 PM
I removed the idle air control (IAC) valve. It had a lot of soot on it. I cleaned the plunger, shaft and hole where it was mounted thoroughly with carburetor cleaner. I also cleaned the throttle body that wasn't too dirty.
I can't help but wonder if you cleaned the TB properly. Unless you do it yearly, most of the time they are neglected and absolutely disgusting. I still think that is your problem.

ontarff
01-26-14, 09:02 PM
I am wondering if the automatic transaxle fluid is a factor? There have not been any low fluid level messages, however, the automatic transaxle fluid was not changed at 50,000 miles. The car has 69,700 on it.

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I can't help but wonder if you cleaned the TB properly. Unless you do it yearly, most of the time they are neglected and absolutely disgusting. I still think that is your problem.

How far back into the manifold do you have to go? The throttle body is only a little over an inch wide. Is there a link to a video?

Ranger
01-26-14, 09:14 PM
Don't worry about the trans fluid. I think even the owners manual calls for a 100K change and even then only if it has seen "severe" service. It would have no effect on the the idle anyway.

No need to clean into the manifold. Just block open the throttle plate and clean as fa back into the TB as you can reach. Don't forget the back side of the throttle plate AND it's perimeter.

I think there is a tutorial in the Tech Tips section.

bodonovich
01-26-14, 09:32 PM
i had a high idle and low idle problem i cleaned the throttle body and IAC very good... i also tighten the hose clamp on the intake plenum boot and it fixed all my problems now it idles perfect

ontarff
01-26-14, 09:36 PM
Is overriding the ISC something to consider?

"The OVERRIDE mode under the PCM section allows you to override the various inputs to the PCM using the WARMER button to increase the value or the COOLER button to lower the value. Overrides include the TCC solenoid (mode PS01), EGR solenoid (PS02), idle speed control motor (PS03)..."

http://www.tomorrowstechnician.com/Article/557/northstar_v8_servicing_gms_topoftheline_engine_lar ry_carley.aspx

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Don't worry about the trans fluid. I think even the owners manual calls for a 100K change and even then only if it has seen "severe" service. It would have no effect on the the idle anyway.

No need to clean into the manifold. Just block open the throttle plate and clean as fa back into the TB as you can reach. Don't forget the back side of the throttle plate AND it's perimeter.

I think there is a tutorial in the Tech Tips section.

I have done that and rechecked twice. TB and plate are clean.

Ranger
01-26-14, 09:38 PM
I think the override function is just a test procedure to check to see if it is working. Can't hurt to try it.

ontarff
01-26-14, 10:01 PM
When the car is started with the engine cold and the trani in PARK, it idles initially at 1100 rpm, but varies about 50 RPM until a "click" is heard. It then stays at 1100 RPM for a short period of time before it starts searching again until another "click" is heard. It repeats this for about 30 seconds then drops down to around 900 RPM where it does the same thing. If the car is then placed in reverse and backed out of the garage, the RPM bounces more. After the engine reaches normal operating temperature and is restarted, it idles stable at around 750 RPM.

ontarff
01-26-14, 11:21 PM
I think the override function is just a test procedure to check to see if it is working. Can't hurt to try it.

This article states,

"There's More, Lots More...
The built-in diagnostics provides access to each of the onboard electronic systems, which you can scroll through using the LO button. To select a system, press the HI button.
If you choose the PCM mode (powertrain control module/ engine), you can again use the LO button to scroll through more display options: DATA, INPUTS, OUTPUTS, OVERRIDES, CLEAR CODES and SNAPSHOT. As before, press HI to select your choice.
Under each of these categories is quite a list of things you can look at. Under PCM data, you can look at all the various sensor inputs, short-term and long-term fuel trim, injector pulse width, engine rpm, battery voltage and PROM identification. Under PCM INPUTS, you can check switch status (throttle position switch, brake pedal switch, transmission gear switches, etc.). Use the PCM OUTPUTS mode to check the EVAP and EGR systems, torque converter clutch solenoid, A/C compressor relay and transaxle solenoids.
The OVERRIDE mode under the PCM section allows you to override the various inputs to the PCM using the WARMER button to increase the value or the COOLER button to lower the value. Overrides include the TCC solenoid (mode PS01), EGR solenoid (PS02), idle speed control motor (PS03), disable individual fuel injectors (PS04), disable fuel pump relay (PS06), cruise control servo (PS07), cooling fan relay (PS08), spark timing advance (PS09), injector flow (PS10) and transaxle shift solenoids (PS10)."

http://www.tomorrowstechnician.com/Article/557/northstar_v8_servicing_gms_topoftheline_engine_lar ry_carley.aspx


I don't know what the override numbers should be changed to. I don't want to screw anything up!

Ranger
01-27-14, 10:46 AM
That's the OBDI system description (pre '96). Your car should be OBDII. I don't think it has overrides.


I don't know what the override numbers should be changed to.
You need a FSM for a clear explanation of all this.

ontarff
01-27-14, 11:28 AM
That's the OBDI system description (pre '96). Your car should be OBDII. I don't think it has overrides.


You need a FSM for a clear explanation of all this.

Thanks Ranger, I have one. I'm going to dig into it today to try and get more information to arrive at a solution. I read through all of the other posts using "high idle" in the advanced search engine. There are many posts that describe similar symptoms that I am experiencing. Unfortunately none of them have a solution other than what I have already tried. I am going to take a look at the oxygen sensor since the problem is associated with a warm restart. I read in another forum the EGR valve and MAP sensor could be the problem too.

Ranger
01-27-14, 11:57 AM
Your description in post #38 gets me thinking. Those RPM increments and timing are somewhat related to the running of the AIR pump. The AIR pump runs at cold start with the RPM at 1200 for about 40 seconds, then the pump shuts down and the RPM drops to about 950 until the ECT reaches a preset temperature that I forget when the PCM drops it to normal idle RPM of 650. Maybe the clicking you hear may be an AIR pump relay? Could it be sticking and requesting higher RPM?

ontarff
01-27-14, 01:11 PM
Your description in post #38 gets me thinking. Those RPM increments and timing are somewhat related to the running of the AIR pump. The AIR pump runs at cold start with the RPM at 1200 for about 40 seconds, then the pump shuts down and the RPM drops to about 950 until the ECT reaches a preset temperature that I forget when the PCM drops it to normal idle RPM of 650. Maybe the clicking you hear may be an AIR pump relay? Could it be sticking and requesting higher RPM?

Could be, I respect your knowledge and experience. How do I troubleshoot the air pump relay? NO DTCs. I can look it up in the FSM.

I found this....

http://www.cadillacforums.com/forums/cadillac-tech-tips-how-fix/118874-how-identify-if-you-have-air.html

Ranger
01-27-14, 03:07 PM
Easiest way I can think of is to swap the relay with a known good one and see if the problem disappears.

ontarff
01-27-14, 03:10 PM
I just ran another test in the garage with my Autoenginuity Scantool software. I started the car cold and it behaved as I described in post #38 above. I let the car run continuously for about 10 minutes until it reached normal operating temperature (199 degree coolant temp).

The bouncing RPM decreased somewhat with time. The clicking sound was coming from the front of the car under the radiator (fans?).

The Scantool showed the following...

B1S1 O2 Sensor Output @ 690 RPM - .045 to .925 volts.
B1S2 O2 Sensor Output @ 690 RPM - pretty steady around .825 volts.
B2S1 O2 Sensor Output @ 690 RPM - .035 to .940 volts.
Airflow Rate MAF Sensor - .53 to .92 hg.
Intake Manifold Pressure (MAP) 9 to 12 hg. with many glitches at 0 (zero).

I then shut the car off and waited about 30 seconds before restarting.
The RPM bounced between 743 to 806 with the A/C ON.
The RPM bounced between 836 to 860 (more stable) with the A/C OFF.

I turned the car OFF and waited for another 30 seconds and restarted.

Same numbers as above, the car never settled down to 690 RPM.

No DTCs.

Ranger
01-27-14, 03:20 PM
The clicking sound was coming from the front of the car under the radiator (fans?).

Unless you are mistaken the A/C clutch engaging and disengaging, I think that could possibly be the fan relays based on that location.

ontarff
01-27-14, 05:48 PM
Now I really have a big problem, I just finished cleaning the TB again (not much there), checked all vacuum lines and the car will not start. It turns over but will not run. I'm getting a B1558 DTC current. I have disconnected the battery and will let it sit for awhile, reconnect the battery, clear any DTCs and attempt a restart. This has never happened before. Now the car is out of service completely. :-(

MoistCabbage
01-27-14, 06:14 PM
That's EPROM checksum error. Usually pops up after the battery's been disconnected, or there's a low voltage issue.

What's your battery voltage?

If you get it started, what's the charging voltage, and is it consistent?

ontarff
01-27-14, 06:16 PM
Unsuccessful attempt at restart. Codes...
B1552 History (PZM module)
B1558 History (PZM module)
U1064 History (PZM module)
U1300 History
U1301 History

Now what? This is ridiculous!

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That's EPROM checksum error. Usually pops up after the battery's been disconnected, or there's a low voltage issue.

What's your battery voltage?

If you get it started, what's the charging voltage, and is it consistent?

I'll hook up a battery charger and charge it for a bit, the engine turns over but won't stay lit.

MoistCabbage
01-27-14, 06:17 PM
Before you charge it, check the voltage readout on the DIC.

ontarff
01-27-14, 06:30 PM
Battery charger indicates battery is charged, headlights are bright, engine turns over but won't stay lit. I don't think it is a low battery.

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Before you charge it, check the voltage readout on the DIC.

DIC 11.7 volts.

10A fuses all OK, (i.e. engine-ignition 0, ignition 1, etc...)

Could I have possibly blown the fuel pump relay?

Submariner409
01-27-14, 06:33 PM
Go back and check all your electrical connections at/near the throttlebody/intake/PCM. Something is fishy.

Less than dead battery - Dead cell ?

ontarff
01-27-14, 07:01 PM
Go back and check all your electrical connections at/near the throttlebody/intake/PCM. Something is fishy.

Less than dead battery - Dead cell ?

All electrical connections checked. The only thing I disconnected and reconnected was the MAF/IAT sensor to remove the air duct.

11.7 was what the message display indicated with the engine off.

Submariner409
01-27-14, 07:12 PM
All electrical connections checked. The only thing I disconnected and reconnected was the MAF sensor to remove the air duct.
11.7 was what the message display indicated with the engine off.

ANY loose clamp or connection in that intake air duct is a suspect.

11.7, key OFF is too low. Most of these cars show 12.3 - 12.6 then. (BUT - these cars can have a high parasitic load until RAP drops out after 10 minutes.)

ontarff
01-27-14, 07:36 PM
ANY loose clamp or connection in that intake air duct is a suspect.

11.7, key OFF is too low. Most of these cars show 12.3 - 12.6 then. (BUT - these cars can have a high parasitic load until RAP drops out after 10 minutes.)

Now 11.8 - KEY ON to read message center. I am charging the battery. MAF/IAT sensor on air duct connection rechecked.

ontarff
01-27-14, 09:33 PM
I replaced fuel pump relay, key ON battery voltage at 12.6, attempted start failed. Starter works fine, engine cranks but will not fire.

I can no longer see the DTCs with my scan tool. The ones I identified in post #49 are still there when retrieving them manually (OFF+warmer).

I ordered a new upgrade connector and software from Autoenginuity today that will enable me to perform the diagnostics identified for the DTC codes in the FSM.

It seems I have opened Pandora's box trying to diagnose an intermittent high idle. The car is useless now until I can figure it out. ICM? PCM? BCM?
I disconnected the battery to hopefully reset the PCM. I'll reconnect in the morning. Please advise.

ontarff
01-28-14, 10:02 AM
Reconnected battery and attempted restart with key ON voltage @ 12.6 volts. Engine cranks with NO start.

Scantool communicating but unable to retrieve cleared DTC codes and actuate anything, awaiting upgrade connector and software.

Codes pulled manually,

IPC B1552 History (PZM/Body Control Module)
PZM B1552 History (PZM/Body Control Module)
PZM B1558 History (PZM/Body Control Module)
PZM B2471 History (PZM/Body Control Module - low voltage in courtesy relay)
RFA U1064 History (PZM/Body Control Module - node alive in class 2 data communications)
MSM U1300 History (Low voltage in class 2 serial data circuit)


MODERATOR: Should I start a new thread?

Please advise...

Ranger
01-28-14, 02:38 PM
May as well keep this one going, but add the code definitions.

drewsdeville
01-28-14, 04:01 PM
Am I the only one that didnt like those MAP spikes when the car was running? O2's are biased rich. Does the tool give any more data? Fuel trims? Other sensory input?

I'd go back to basics here, with the no-start. Check for spark, check for fuel.

ontarff
01-28-14, 11:28 PM
Am I the only one that didnt like those MAP spikes when the car was running? O2's are biased rich. Does the tool give any more data? Fuel trims? Other sensory input?

I'd go back to basics here, with the no-start. Check for spark, check for fuel.

Yes, it gives O2 sensor fuel trims and other sensory input. The new upgrade is even more comprehensive.

I'll be starting with the "Engine Cranks but Does Not Turn" diagnostics on page 6-905 of the FSM.

I appreciate all of the advice from this forum.

ontarff
01-29-14, 02:08 PM
There is good information from N*Caddy post #15 here,

http://www.cadillacforums.com/forums/cadillac-seville-cadillac-eldorado-forum/274358-p0231-97-eldorado-cranks-but-wont.html

I did all the things he listed. The fuses all look OK, I replaced the fuel pump relay. I depressed the pin on the fuel rail service port and fuel came out for a second and stopped. I then turned the ignition on and heard the fuel pump for a couple seconds. I then depressed the pin on the fuel rail service port again and more fuel came out. (I don't have a pressure gauge). The fuel pump is heard at the fuel fill when the ignition is turned on. The fuel pump relay clicks when the ignition is turned on. Based on this I believe the fuel pump is not the problem and fuel is getting to the injectors.

I am still waiting for the new Autoenginuity connector and software to arrive.

According to this page

http://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

the DTC code definitions are

DTC B1552 Keep Alive Memory (KAM) Error
DTC B1558 BCM EPROM Checksum Error
DTC B2471 Interior Lamp Fault
DTC U1064 Loss of Communications with DIM
DTC U1300 Class 2 Short to Ground
DTC U1301 Class 2 Short to Battery

They are all HISTORY. Only the B1558 was CURRENT after the no start problem occurred. I cleared it.

According to the FSM, DTC U1300 will not show as CURRENT.

Is the U1300 code the main problem? I understand this class 2 system is used for all the modules (i.e., PCM, ICM, BCM etc.) to communicate with each other. The U1301 code was probably set when I disconnected the battery.

ontarff
01-31-14, 12:53 PM
I got the new connector, here is what I am getting,

181833

The battery is low, I am currently recharging it. I got many low voltage DTCs added to what I have already identified. On page 6-672 of the FSM, step 8, "Diagnostic System Check - Engine Controls" says to go to DTC code list. Where should I start? I just ordered the fuel injector test lamp needed for step 6 on page 6-905 of the FSM "Engine Cranks but Does Not Run".

Ranger
01-31-14, 02:45 PM
Start with a good battery. Low voltage will wreak havoc with the system.

ontarff
01-31-14, 06:03 PM
Start with a good battery. Low voltage will wreak havoc with the system.

Battery is recharged 12.6 DIC, attempted start (failed) 12.48 now.

ontarff
02-03-14, 07:26 PM
Cranking stops after 2 seconds, is this normal? I thought it should crank continuously until I turn the key back from start or the car starts. Fuel pressure is in normal range. I am now waiting for an ignition injector test light to arrive to see if PCM is sending signals to injectors. I am still wondering if a failed BCM could cause this.

Ranger
02-03-14, 08:51 PM
No, the BCM has nothing to do with the powertrain.


Cranking stops after 2 seconds, is this normal? I thought it should crank continuously until I turn the key back from start or the car starts.
No, that's not normal. It should crank until it starts, you release the key, kill the battery or burn up the starter.

ontarff
02-03-14, 09:12 PM
No, the BCM has nothing to do with the powertrain.


No, that's not normal. It should crank until it starts, you release the key, kill the battery or burn up the starter.

What could cause this? No PCM Pxxxx DTCs. I can repeat it until battery gets weak.

Ranger
02-03-14, 09:24 PM
It can only be something that is not monitored, like a throttle cable, dirty TB, something on that order is all I can think of.

ontarff
02-03-14, 09:46 PM
It can only be something that is not monitored, like a throttle cable, dirty TB, something on that order is all I can think of.

Nothing in the FSM to help me on this one. The throttle cable is fine and the TB was cleaned again just before this problem occurred.

Ranger
02-03-14, 09:49 PM
:noidea: I think we have thought of and suggested every possibility. I'm out of ideas.

ontarff
02-03-14, 10:38 PM
:noidea: I think we have thought of and suggested every possibility. I'm out of ideas.

I appreciate your help Ranger. I guess the last resort is to call for a tow and send it to the dealer $$$$$. I've spent almost $700 in new tools and parts so far.

Submariner409
02-04-14, 08:15 AM
Have we discussed the 2001 - 2002 ignition switch problems ? The switch that is attached to the key cylinder. That will cause weird no-start problems. Dash removal required. Mine was replaced under warranty when the car was 8 months "old" - before I bought it........... reason: nagging no-start condition. I have the GM warranty repair order.

ontarff
02-04-14, 10:29 AM
Have we discussed the 2001 - 2002 ignition switch problems ? The switch that is attached to the key cylinder. That will cause weird no-start problems. Dash removal required. Mine was replaced under warranty when the car was 8 months "old" - before I bought it........... reason: nagging no-start condition. I have the GM warranty repair order.

No, this wasn't discussed. Was it a no starter actuation, or starter cut out after a couple seconds problem, or both?

I found one of the threads here...this was an intermittent no starter actuation problem. No DTCs.

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/173136-starting-problem-2001-deville.html

ontarff
02-04-14, 12:44 PM
I cleaned he positive battery terminal. It is cranking fine now, just won't fire up. I am watching the mail for the ignition injector test light. Disregard earlier post #65 on starter cutting out. I am on hold at step 6 (page 6-905) in the FSM for "Engine Cranks but Does Not Turn".

----------

I believe the 10A fuse PCM (BAT) circuit is not right. I am getting a red light on my circuit test light tool with key on and off (open ciruit?). When I exchange it with another 10A fuse it is good in another location on the fuse panel (green light). Visually, it looks good as well. The PCM (IGN) fuse is also hot with key off and is closed (green light) as it should be. Page 6-639 of the FSM shows the schematic for the PCM. It shows the PCM (BAT) fuse is supposed to be hot at all times with the battery connected. My VOM shows 10.26 volts, is this correct?

ontarff
02-04-14, 04:06 PM
I think I found the problem, one of the wires (yellow) is disconnected from the MAF sensor connector on the air duct. I unwrapped/cut the black tape to find it. Now I have to figure out how to reconnect it. Can you stick a wire back into the connector securely?

Reference FSM page 6-893 "Hard Start" Sensor/System.


That's it!!! Engine is running again. Now back to the intermittent high idle problem....whew!

ontarff
02-04-14, 05:05 PM
Idle is still high...Using FSM page 6-924, Idle Air Control (IAC) System Diagnosis

183201

drewsdeville
02-04-14, 06:05 PM
All numbers look fine there - granted, they are static and we can't see any trends with just a screen shot.

Can the program give you a status of the power steering switch?

It seems odd to me that the computer knows the rpm is above desired, yet isn't commanding that IAC down... Does this setup operate the IAC via a duty cycle? If so, unplugging it should give a reaction - either severely dropping the RPM or killing the engine.

How about some fueling numbers? Earlier, you posted some O2 voltages that should be of concern, whether related to the high idle or not. Investigating may help lead you to a solution to your problem. I see you have some graphing capabilities - even better. Any fuel trim and O2 data available?

ontarff
02-04-14, 07:16 PM
All numbers look fine there - granted, they are static and we can't see any trends with just a screen shot.

Can the program give you a status of the power steering switch?

It seems odd to me that the computer knows the rpm is above desired, yet isn't commanding that IAC down... Does this setup operate the IAC via a duty cycle? If so, unplugging it should give a reaction - either severely dropping the RPM or killing the engine.

How about some fueling numbers? Earlier, you posted some O2 voltages that should be of concern, whether related to the high idle or not. Investigating may help lead you to a solution to your problem. I see you have some graphing capabilities - even better. Any fuel trim and O2 data available?

The IAC is controlled through the DLC. Here is the fuel trim and O2 data...

183257

183249

I didn't see a way to determine the position of the power steering switch.

Ranger
02-04-14, 08:52 PM
I think I found the problem, one of the wires (yellow) is disconnected from the MAF sensor connector on the air duct. I unwrapped/cut the black tape to find it. Now I have to figure out how to reconnect it. Can you stick a wire back into the connector securely?

Yes, I've done it more than once. Use a magnifying glass and a straight pin. You should be able to see the locking tab in the connector. Press it down with the pin and pull the wire. You'll then have to uncrimp and recrimp it, but it is doable.

ontarff
02-04-14, 09:24 PM
Yes, I've done it more than once. Use a magnifying glass and a straight pin. You should be able to see the locking tab in the connector. Press it down with the pin and pull the wire. You'll then have to uncrimp and recrimp it, but it is doable.

It is amazing how one little wire on what seems a peripheral sensor connector (with no DTC pointing to the MAF sensor) can cause so much hassle and render the vehicle useless. I had to go back and jump to several diagnostic tables in the FSM before being prompted to check the integrity of the MAF sensor connection under the black tape wrap. The wire must have come off after removing the air duct several times to clean the TB and install the TPS. I was almost ready to call for a tow truck to take it to the Caddie dealer. Wow, am I relieved not to have spent a lot of $$$$ on a little wire. That PCM (BAT) fuse was a distraction as well. Now....to pursue the damn idle control problem.

ontarff
02-05-14, 03:01 PM
Yes, I've done it more than once. Use a magnifying glass and a straight pin. You should be able to see the locking tab in the connector. Press it down with the pin and pull the wire. You'll then have to uncrimp and recrimp it, but it is doable.

I can't figure out where to crimp the wire on the connector. It is still loose. I am concerned about it slipping out while driving the car and causing an accident.

I just ordered this part with the pigtail.

183497

ontarff
02-05-14, 05:26 PM
Tests run today to try and determine cause for high idle.

183505

183529

This is at idle in the garage. I am going to use the data logging feature of this software to record a trip in the car when the high idle gets hung around 1100-1200 RPM.

drewsdeville
02-05-14, 07:22 PM
The last screenshot isnt very legible - perhaps due to resizing... Am I seeing those long term fuel trims correctly (11%)?

The O2 graph is...interesting - with occasional periods of zero cross counts. What time scale is used there? Seconds?

If possible, chart the MAP and MAF readings with the O2s and trims while its acting up.

ontarff
02-05-14, 09:28 PM
The last screenshot isnt very legible - perhaps due to resizing... Am I seeing those long term fuel trims correctly (11%)?

The O2 graph is...interesting - with occasional periods of zero cross counts. What time scale is used there? Seconds?

If possible, chart the MAP and MAF readings with the O2s and trims while its acting up.

You can right click on the images and save them to your desktop and resize them. I had to resize them to 1024 pixels for this thread.

I plan to record the high idle problem when it is acting up. I will have to take my laptop computer in the car with the DLC connector attached and start the scantool program for data logging on the drive home.

This image gives a graph of all sensors and reading parameters, I had to delete a couple of the images.

183585

Ranger
02-05-14, 09:43 PM
I can't figure out where to crimp the wire on the connector. It is still loose. I am concerned about it slipping out while driving the car and causing an accident.

I just ordered this part with the pigtail.

183497
A new connector would be the best way to go, but to repair it you have to open the white lock. Then you can disassemble the connector.

ontarff
02-05-14, 10:22 PM
A new connector would be the best way to go, but to repair it you have to open the white lock. Then you can disassemble the connector.

There isn't a white lock on the original connector. I was thinking I'd wedge something (toothpick?) in the back to secure the wire until I can replace it in the next couple days. I tried pushing with a safety pin on all those black tabs. I feel stupid not being able to reattach a wire! On the schematic, the yellow wire goes to the PCM.

183641

Ranger
02-06-14, 10:31 AM
On this one the locking tab is the black tab above the green weather seal.

Note the locking tabs (barbs) on the terminals? THAT is what needs to be depressed in order to pull the wire (with the pin still attached).
http://www.rowand.net/shop/tech/images/AutomotiveElectricalConnector-MateLock.jpg

http://www.youtube.com/watch?v=CFM-6ovP_-k

ontarff
02-15-14, 05:05 PM
Still getting the intermittent high idle (1100 RPM) when the transmission is in DRIVE and goes above 1200 RPM while driving after a warm restart. Coming to a complete stop with the high idle drops down to about 1000 RPM. After the high idle in gear occurs, if I shift to N or P, RPM goes up to 1700. Trani doesn't like the high idle shifting down to low gear either. Shutting engine off for 15 seconds resets idle to normal until tranni is placed in D and driven above 1200 RPM. With the new AutoEnginuity scantool I am getting the P0507 DTC history for the Enhanced Powertrain and Transmission.

186105

The FSM diagnostics calls for using the J351616-A test adapter kit. This is an expensive item.

I pulled out the IAC and checked it again. It was very clean.

Please advise.

ontarff
02-15-14, 05:55 PM
This doesn't seem good either...

186129

186137

I think some of these sensor parameters are RED because they are switched?

drewsdeville
02-16-14, 02:00 PM
I don't know how your specific program is interpreting the data, but you are showing an 'engine load' value of zero with the engine running. That should be a flag as that is impossible. Unfortunately, I don't know this specific system off the top of my head, but I would assume the system uses the MAP value as part of the load calculation, since a MAP exists on this system (load is a linear function of vacuum). Perhaps your service manual will guide you...

It seems a little coincidental that you mentioned funky MAP spikes earlier in the thread. After you saw the erratic MAP data last time, did you pursue a MAP problem or did you ignore it? Unfortunately, while your charts include the BARO value, which looks fine, they don't include a MAP value.

MoistCabbage
02-16-14, 05:02 PM
Quick and dirty test - Does it idle normally with the MAP disconnected?

ontarff
02-16-14, 07:33 PM
I don't know how your specific program is interpreting the data, but you are showing an 'engine load' value of zero with the engine running. That should be a flag as that is impossible. Unfortunately, I don't know this specific system off the top of my head, but I would assume the system uses the MAP value as part of the load calculation, since a MAP exists on this system (load is a linear function of vacuum). Perhaps your service manual will guide you...

It seems a little coincidental that you mentioned funky MAP spikes earlier in the thread. After you saw the erratic MAP data last time, did you pursue a MAP problem or did you ignore it? Unfortunately, while your charts include the BARO value, which looks fine, they don't include a MAP value.

Engine Load @ 2%.

186521


The FSM calls for testing IAC voltage continuity with a test light at the IAC connector harness. I am trying to figure out how to to do this without the J 35616-A test kit. Since both the original and new IACs were having the same problem and I can see the IAC count change up and down when I command a change in RPM with the scantool, I am guessing it is the signal from the PCM (ECM) that is causing the problem. I can't get the problem to occur in the garage in PARK. I would have to drive home with the problem, pull into the garage, shove it in PARK (the engine would climb to about 1700-2000+ RPM), hook up the test light, unplug the harness to check for voltage continuity. This isn't going to happen, it's not safe. I am guessing a bad PCM at this point.

ontarff
02-16-14, 08:52 PM
MAP sensor data...(delayed)

MODERATOR: I need more image space (exceeds quota). I cannot upload additional images to this thread.

Please advise.

MoistCabbage
02-16-14, 09:13 PM
Just upload pictures to www.photobucket.com , then post the IMG codes here.

The small pics you can post with the site limitations are sometimes difficult to read anyway.

Did you try just unplugging the sensor and seeing if idle improves?

ontarff
02-16-14, 10:12 PM
Just upload pictures to www.photobucket.com , then post the IMG codes here.

The small pics you can post with the site limitations are sometimes difficult to read anyway.

Did you try just unplugging the sensor and seeing if idle improves?

No, not yet. I am going to replace the PCV valve and try that tomorrow.

Here is the image I captured on the MAP sensor, it looks OK.

http://i1231.photobucket.com/albums/ee518/dmpierce/MAPsensor.jpg (http://s1231.photobucket.com/user/dmpierce/media/MAPsensor.jpg.html)

ontarff
02-17-14, 04:32 PM
Car ran perfect today to a 10 mile destination. After sitting for a couple of hours it ran fine on the return trip home until I turned into the driveway and the idle jumped up and stuck at 1100 RPM. The power steering pump prompts the engine idle to increase. I shut the ignition off and restarted after a few minutes and the idle returned to normal. I turned the steering wheel left and right, stop to stop, to try and get the idle to come up again in PARK. It would not increase. Could this be part of the problem? This has happened on a couple other occasions with the car in DRIVE. The car idles the same with the MAP sensor disconnected. Current DTC P0507.

Should the Torque Request Signal be this high @ 90%? This signal goes to the Electronic Brake Control Module (EBCM).

http://i1231.photobucket.com/albums/ee518/dmpierce/TorqueRequestSignal.jpg (http://s1231.photobucket.com/user/dmpierce/media/TorqueRequestSignal.jpg.html)

ontarff
02-21-14, 07:38 PM
I just received the Kent-Moore J-37027-1A IAC motor driver to diagnose the high idle problem.

Now, with the IAC motor driver, I commanded an increase in RPM and a decrease in RPM while checking for PCM circuit continuity with a test light on the IAC connector pins as directed by the FSM on page 6-831 for the DTC P0507 diagnostic. Here is the image from the scan tool. Notice the erratic IAC signal from the PCM. I saw the light flashing on the test light as well. With this information the FSM points to PCM replacement in step 15 on page 6-832.

http://i1231.photobucket.com/albums/ee518/dmpierce/IACMotorSignalfromPCM2-22-2014.jpg (http://s1231.photobucket.com/user/dmpierce/media/IACMotorSignalfromPCM2-22-2014.jpg.html)

Do you guys agree this PCM is bad? Is it best to take the car to the dealer for the PCM replacement? I don't know anyone who can program a new PCM.

ontarff
02-23-14, 12:11 PM
Repeat test this morning...

Engine start, erratic surging.

http://i1231.photobucket.com/albums/ee518/dmpierce/6d7ed206-714d-4563-8413-4019202e123c.png (http://s1231.photobucket.com/user/dmpierce/media/6d7ed206-714d-4563-8413-4019202e123c.png.html)

Warm up....everything smooth, settled down.

http://i1231.photobucket.com/albums/ee518/dmpierce/2a6fcc8b-e99a-470d-91a4-bb2b3c7ab15d.png (http://s1231.photobucket.com/user/dmpierce/media/2a6fcc8b-e99a-470d-91a4-bb2b3c7ab15d.png.html)

Test with IAC motor driver attached to IAC, notice erratic IAC counts from PCM.

http://i1231.photobucket.com/albums/ee518/dmpierce/6d551281-d6b0-4038-848a-50f20fd96e57.jpg (http://s1231.photobucket.com/user/dmpierce/media/6d551281-d6b0-4038-848a-50f20fd96e57.jpg.html)

Notice how the PCM signal to the IAC gets weird at 1100 RPM, that is where the high idle hangs in DRIVE.

Submariner409
02-23-14, 01:10 PM
Haven't looked back through the thread - - - - have you removed the PCM, unplugged the two huge multi-pin connectors and hooked it all up again ? Might be worth a (5 minute) shot in the dark.

ontarff
02-24-14, 12:06 AM
Haven't looked back through the thread - - - - have you removed the PCM, unplugged the two huge multi-pin connectors and hooked it all up again ? Might be worth a (5 minute) shot in the dark.

No, I haven't done that yet. I'll try that and report back. I'm hoping I can find someone to program a new PCM if all else fails. Last resort....dealer$$$$.

ontarff
02-24-14, 07:50 PM
Haven't looked back through the thread - - - - have you removed the PCM, unplugged the two huge multi-pin connectors and hooked it all up again ? Might be worth a (5 minute) shot in the dark.

OK, I got the air filter off and the corner brace but I can't open the plastic air inlet housing containing the PCM. I released one clip but can't get to any other on the other side. The plastic electrical conduit running over the top of the air inlet housing doesn't want to move anywhere. The FSM makes no mention of this problem.

http://i1231.photobucket.com/albums/ee518/dmpierce/DSCN3353.jpg (http://s1231.photobucket.com/user/dmpierce/media/DSCN3353.jpg.html)

Yes, that's the new connector on the MAF sensor.

ontarff
02-26-14, 03:43 PM
Okay, since nobody on this forum gave me any advice on getting to the PCM, I put everything back together and drove the car today. It behaved normally until I was almost home and the MIL illuminated. When I got home I connected the scan tool to see what DTCs were set.

I got this on start-up

http://i1231.photobucket.com/albums/ee518/dmpierce/MIL2-26-2014.png (http://s1231.photobucket.com/user/dmpierce/media/MIL2-26-2014.png.html)

I got this when I actuated the RPM up to 1700 RPM

http://i1231.photobucket.com/albums/ee518/dmpierce/f7e64d41-597d-4e9c-9cb2-f8696e6556a1.png (http://s1231.photobucket.com/user/dmpierce/media/f7e64d41-597d-4e9c-9cb2-f8696e6556a1.png.html)

I cleared the MIL and DTCs, shut the engine off and restarted. I got this...interesting.

http://i1231.photobucket.com/albums/ee518/dmpierce/AfterMILCleared.png (http://s1231.photobucket.com/user/dmpierce/media/AfterMILCleared.png.html)

drewsdeville
02-26-14, 04:27 PM
Bank one fuel trim total = 17.94%
Bank two fuel trim total = 19.50%

These indicate a lean condition. The problem is global, since both banks are affected equally. The next step would be to determine under what conditions the lean condition exists. Only low rpm/idle = vacuum leak. Under load/high rpm points to a possible MAF/MAP problem.

Take readings under different conditions and report back.

Load calculation still seems odd as well - still not sure what this system uses to calculate load... maybe someone else does.

ontarff
02-26-14, 06:58 PM
Bank one fuel trim total = 17.94%
Bank two fuel trim total = 19.50%

These indicate a lean condition. The problem is global, since both banks are affected equally. The next step would be to determine under what conditions the lean condition exists. Only low rpm/idle = vacuum leak. Under load/high rpm points to a possible MAF/MAP problem.

Take readings under different conditions and report back.

Load calculation still seems odd as well - still not sure what this system uses to calculate load... maybe someone else does.

This Freeze Frame for the P0507 DTC was taken at idle. If there were a vacuum leak, it would be consistent each time the car is run, hot or cold.

Bank one long term fuel trim total = 17.94%
Bank two long term fuel trim total = 15.60%

This MIL was a first time occurrence. I am planning on taking the car to the dealer to replace the PCM if they find (as I have) that it is indeed the source of the problem. I wish I could watch them remove it.

drewsdeville
02-26-14, 10:39 PM
Bank one long term fuel trim total = 17.94%
Bank two long term fuel trim total = 15.60%



If you have bolded this to imply a correction, my 19.50% claim is the TOTAL fuel trim correction to bank 2 (long term + short term). If the condition exists long enough, the long term will adjust to 19.5% (it's goal is to keep short term at 0).

While it is possible, I'd be surprised if the PCM was the problem. I think you haven't gotten anywhere because you've focused on the idle speed by assuming it's "the" problem rather than considering it's the result of an underlying problem. DTC's are merely guides (sometimes fruitless ones at that), NOT answers. Just because you have an idle speed code doesn't mean the idle speed diagnostic tree will net the correct answer. You've ignored a lot of flags discovered along your journey (MAP spikes, erratic O2 voltages, large fuel trim corrections)... even if the IAC problem is it's own, you still clearly have problems outside of the IAC circuit.

That said, I hope I'm wrong and the PCM replacement ends your headache!

If interested, taking a step back and reflecting on what has been done, what I would suggest you focus on the known symptoms. At least one engine management function, and the IAC are malfunctioning. You have data spikes from both the MAP and IAC, according to your charts and observations. Quite coincidental, no? Perhaps it would be beneficial to check the wiring diagrams to see if those two circuits share a common reference or ground (very much possible), and get a SCOPE (not a VOM) on them.

ontarff
02-27-14, 01:02 AM
If you have bolded this to imply a correction, my 19.50% claim is the TOTAL fuel trim correction to bank 2 (long term + short term). If the condition exists long enough, the long term will adjust to 19.5% (it's goal is to keep short term at 0).

While it is possible, I'd be surprised if the PCM was the problem. I think you haven't gotten anywhere because you've focused on the idle speed by assuming it's "the" problem rather than considering it's the result of an underlying problem. DTC's are merely guides (sometimes fruitless ones at that), NOT answers. Just because you have an idle speed code doesn't mean the idle speed diagnostic tree will net the correct answer. You've ignored a lot of flags discovered along your journey (MAP spikes, erratic O2 voltages, large fuel trim corrections)... even if the IAC problem is it's own, you still clearly have problems outside of the IAC circuit.

That said, I hope I'm wrong and the PCM replacement ends your headache!

If interested, taking a step back and reflecting on what has been done, what I would suggest you focus on the known symptoms. At least one engine management function, and the IAC are malfunctioning. You have data spikes from both the MAP and IAC, according to your charts and observations. Quite coincidental, no? Perhaps it would be beneficial to check the wiring diagrams to see if those two circuits share a common reference or ground (very much possible), and get a SCOPE (not a VOM) on them.

Yes, I thought there was a typo, hence the bold type. I don't have a chart that indicates MAP or O2 sensor spiking. I will run more tests to look for these and post them. There is no urgency to waste the money on a PCM replacement. As you stated, I was only following the FSM diagnostic table for the P0507 DTC. What are the normal fuel trim parameters at idle?

drewsdeville
02-27-14, 07:23 AM
If everything was operating normally, you'd have a fuel trim pretty close to zero - certainly nothing higher than 10%. You are approaching 20%, well over double 'the norm'...

Perhaps I'm recalling a different thread, but weren't you observing MAP spikes (occasional values of zero) and biased O2 voltages (not crossing 0.45)?

ontarff
02-27-14, 01:29 PM
Here are this morning's tests,

Engine start

http://i1231.photobucket.com/albums/ee518/dmpierce/ab123648-5560-4b14-9fee-1f789ee71405.png (http://s1231.photobucket.com/user/dmpierce/media/ab123648-5560-4b14-9fee-1f789ee71405.png.html)

Initial idle

http://i1231.photobucket.com/albums/ee518/dmpierce/56a8ea5d-1074-450a-82ff-f35ec7c10629.png (http://s1231.photobucket.com/user/dmpierce/media/56a8ea5d-1074-450a-82ff-f35ec7c10629.png.html)

Warm up, notice the change in signals when RPM drops

http://i1231.photobucket.com/albums/ee518/dmpierce/cd115ef2-dcc8-42b5-b5c5-5c88e65c13d6.png (http://s1231.photobucket.com/user/dmpierce/media/cd115ef2-dcc8-42b5-b5c5-5c88e65c13d6.png.html)

Increase to 1700 RPM watching MAF and MAP sensors

http://i1231.photobucket.com/albums/ee518/dmpierce/91c49e80-cdfe-4312-8924-a51b74cce603.png (http://s1231.photobucket.com/user/dmpierce/media/91c49e80-cdfe-4312-8924-a51b74cce603.png.html)

Decrease engine RPM back to idle, note signals from MAP voltage (no spikes) and IAC counts
http://i1231.photobucket.com/albums/ee518/dmpierce/6abb71f6-8ba5-4792-8fc3-5bec12a322ed.png (http://s1231.photobucket.com/user/dmpierce/media/6abb71f6-8ba5-4792-8fc3-5bec12a322ed.png.html)

Fuel trim at idle looks good

http://i1231.photobucket.com/albums/ee518/dmpierce/276e0f39-91cb-4340-97a8-8dca7491239d.png (http://s1231.photobucket.com/user/dmpierce/media/276e0f39-91cb-4340-97a8-8dca7491239d.png.html)

O2 sensor output voltages on both banks at idle

http://i1231.photobucket.com/albums/ee518/dmpierce/814492a9-ef75-4439-877e-ba9f233d8daf.png (http://s1231.photobucket.com/user/dmpierce/media/814492a9-ef75-4439-877e-ba9f233d8daf.png.html)

Sensor readings

http://i1231.photobucket.com/albums/ee518/dmpierce/LiveDataGrid1.png (http://s1231.photobucket.com/user/dmpierce/media/LiveDataGrid1.png.html)

http://i1231.photobucket.com/albums/ee518/dmpierce/LiveDataGrid2.png (http://s1231.photobucket.com/user/dmpierce/media/LiveDataGrid2.png.html)

http://i1231.photobucket.com/albums/ee518/dmpierce/LiveDataGrid3.png (http://s1231.photobucket.com/user/dmpierce/media/LiveDataGrid3.png.html)

Back up to 1700 RPM, notice IAC signal

http://i1231.photobucket.com/albums/ee518/dmpierce/e690f596-ee56-49da-81df-d46643a2fb9c.png (http://s1231.photobucket.com/user/dmpierce/media/e690f596-ee56-49da-81df-d46643a2fb9c.png.html)

Back down to idle (still high), no MAP voltage spikes.

http://i1231.photobucket.com/albums/ee518/dmpierce/97a2028e-b7d7-4ef6-a086-e1ed3c8fb81c.png (http://s1231.photobucket.com/user/dmpierce/media/97a2028e-b7d7-4ef6-a086-e1ed3c8fb81c.png.html)

drewsdeville
02-28-14, 05:42 PM
Fuel trim at idle looks good

http://i1231.photobucket.com/albums/ee518/dmpierce/276e0f39-91cb-4340-97a8-8dca7491239d.png (http://s1231.photobucket.com/user/dmpierce/media/276e0f39-91cb-4340-97a8-8dca7491239d.png.html)

O2 sensor output voltages on both banks at idle

http://i1231.photobucket.com/albums/ee518/dmpierce/814492a9-ef75-4439-877e-ba9f233d8daf.png (http://s1231.photobucket.com/user/dmpierce/media/814492a9-ef75-4439-877e-ba9f233d8daf.png.html)

Sensor readings



http://i1231.photobucket.com/albums/ee518/dmpierce/LiveDataGrid2.png (http://s1231.photobucket.com/user/dmpierce/media/LiveDataGrid2.png.html)

http://i1231.photobucket.com/albums/ee518/dmpierce/LiveDataGrid3.png (http://s1231.photobucket.com/user/dmpierce/media/LiveDataGrid3.png.html)





The first graph is only the short term trim. Since it's hovering very tightly around 0, we can be sure that the PCM has good control over the A/F mixture, and that the ignition and fuel systems themselves are probably working correctly and in good tune. However, if you look at the charts below the graph, you'll see 15% and 16% long term. This tells us that the PCM's adjustments are justified, and that there certainly is a problem.

You have a lot of data posted, but frankly, it's still difficult to diagnose over the internet. What I suggest is that, for now, you ignore the idle speed problem, and focus on correcting the engine management problem. You may end up killing to birds with one stone.

Looks like the lean condition exists under all load/rpm conditions, and probably increasing at higher rpm (you had 20% correction at 1700 rpm - any readings around say 3000rpm?)...which makes me suspicious of the air intake leaks and incorrect MAF sensor readings.

ontarff
03-01-14, 02:10 PM
The first graph is only the short term trim. Since it's hovering very tightly around 0, we can be sure that the PCM has good control over the A/F mixture, and that the ignition and fuel systems themselves are probably working correctly and in good tune. However, if you look at the charts below the graph, you'll see 15% and 16% long term. This tells us that the PCM's adjustments are justified, and that there certainly is a problem.

You have a lot of data posted, but frankly, it's still difficult to diagnose over the internet. What I suggest is that, for now, you ignore the idle speed problem, and focus on correcting the engine management problem. You may end up killing to birds with one stone.

Looks like the lean condition exists under all load/rpm conditions, and probably increasing at higher rpm (you had 20% correction at 1700 rpm - any readings around say 3000rpm?)...which makes me suspicious of the air intake leaks and incorrect MAF sensor readings.

I took the car to the dealer. I paid them the $110 for an estimate. They wanted to charge me $480 to replace the 8 intake manifold gaskets to correct the excessive fuel trim. I spoke with the N* technician who worked on the car. I explained to him that the gaskets were relatively new as I changed them when I installed the new plenum in 2010. He told me that I could probably fix the problem by torquing the intake air manifold bolts down a little more (about a quarter to half turn). He said the gaskets probably lost a little elasticity from the engine heat cycles after the plenum installation. His only recommendation on the high idle was to buy another AC Delco TPS to remove the aftermarket one I installed purchased from NAPA. He didn't think it was a PCM problem I told him I used the FSM diagnostic flow chart and he said, "yeah, sometimes those diagnostic flow charts in the manual want you to replace parts unnecessarily". That keeps the high idle cause a mystery!

The car operated fine with no high idle returning from the dealer (typical for a cold start). This morning I had to first unplug the injectors and remove the fuel rail (pain in the axx) just so I could tighten the air intake bolts a little more. Particularly the bolt that is right next to the fuel rail anchor point on the rear bank adjacent to the EGR valve. I torqued them all about a quarter to half turn, put everything back together and turned the engine on. I then sprayed MAP sensor cleaner with a straw on the nozzle around the plenum, TB and air intake manifold. No change in engine RPM, indicating an air leak. I'm going to run some more tests with the scantool on Monday. What is the maximum long term fuel trim parameter?

drewsdeville
03-01-14, 02:44 PM
Usually +/- 25% is the standard min max. Perhaps your service manual gives that info...

ontarff
03-01-14, 05:42 PM
Usually +/- 25% is the standard min max. Perhaps your service manual gives that info...

If so, why should long term trims @ 16% be a concern with short term trims @ < 2 percent? I will try to find that information in the service manual.

Thanks.

Here is a test I just ran, long term trim on both banks is < 10% @ idle.

http://i1231.photobucket.com/albums/ee518/dmpierce/FuelTrimsLiveData.png (http://s1231.photobucket.com/user/dmpierce/media/FuelTrimsLiveData.png.html)

ontarff
03-02-14, 01:56 AM
OK, I got the air filter off and the corner brace but I can't open the plastic air inlet housing containing the PCM. I released one clip but can't get to any other on the other side. The plastic electrical conduit running over the top of the air inlet housing doesn't want to move anywhere. The FSM makes no mention of this problem.

http://i1231.photobucket.com/albums/ee518/dmpierce/DSCN3353.jpg (http://s1231.photobucket.com/user/dmpierce/media/DSCN3353.jpg.html)

Yes, that's the new connector on the MAF sensor.

Still waiting for advice on how to get the PCM out of jail (the plastic box) to check the connectors without taking out the wiring conduit connecting the headlights, parking lights, horn and and other stuff on the front end. The plastic electrical conduit cannot be moved, it is fastened with no slack.

ontarff
03-05-14, 08:21 PM
The high idle problem reoccurred today after a warm restart on a 60 mile trip. I guess this will remain a mystery as nobody on this forum and the dealer technician can diagnose the cause.

drewsdeville
03-05-14, 09:29 PM
Your fuel trim numbers are all over the place - different every time you post. Time to start organizing this data.

Get a fresh set. Get fuel trims, short and long, at idle, at 2000rpm, and at 4000rpm. Also, chart O2 voltages (as you did in post #108) at WOT, at least long enough to get through first gear.

ontarff
03-05-14, 10:26 PM
Your fuel trim numbers are all over the place - different every time you post. Time to start organizing this data.

Get a fresh set. Get fuel trims, short and long, at idle, at 2000rpm, and at 4000rpm. Also, chart O2 voltages (as you did in post #108) at WOT, at least long enough to get through first gear.



I will have to get someone to drive the car and hope the problem occurs while I operate the scan tool on my laptop to record the tests you have identified. Are there any other known malfunctions with the N* or other 2001 Cadillac ETC components that cause erratic fuel trim numbers (i.e. air/vacuum leak, MAF sensor, PCM, etc.) and cause the P0507 DTC? I will try to research this in the service manual and other posts on this forum. There are no known posts to me, that point to an erratic long/short term fuel trim with an inconsistent high idle (1100 RPM) occurring in DRIVE initiated only after a warm engine restart. I am going to order another AC Delco TPS as the dealer tech advised.

drewsdeville
03-05-14, 10:49 PM
There are no known posts to me, that point to an erratic long/short term fuel trim with an inconsistent high idle (1100 RPM) occurring in DRIVE initiated only after a warm restart.

You are still making an assumption that you are having a problem ONLY under those specific conditions... The numbers have been hinting that the problem extends well outside of them, even though you can't hear/feel them.

rodnok01
03-05-14, 11:11 PM
I need to check the whole post to see shy you changed the TPS, they are easily checked with meter or even your computer readout. A pefectly smooth reading from close to wot and its good. Most go bad and cause an off idle die not a rough idle from my experiences.

ontarff
03-06-14, 11:11 PM
I need to check the whole post to see shy you changed the TPS, they are easily checked with meter or even your computer readout. A pefectly smooth reading from close to wot and its good. Most go bad and cause an off idle die not a rough idle from my experiences.

The dealer technician told me the aftermarket TPS sensor I installed can be off 7% with no DTC set. His only guess at correcting the intermittent high idle was replacing the TPS with an AC Delco part. There has never been a rough idle problem.

ontarff
03-07-14, 12:44 AM
A good explanation of the fuel trim numbers,

http://www.obd-codes.com/faq/fuel-trims.php

ontarff
03-15-14, 12:20 AM
I did everything the dealer technician and everyone else on this forum has advised. I tightened down the 10 intake manifold bolts to eliminate a possible air leak that may cause the rich fuel trim numbers and replaced the TPS again with what appeared to be an identical AC Delco part ($49). The high idle problem (1100 RPM in DRIVE) after a warm restart persists. I notice that an uphill grade can raise coolant temp and trigger the high idle as well. I am thinking that the problem is related to engine temperature. It is hard for me to understand how this remains a mystery. I have done everything anyone has advised to fix the problem. I have spent close to $900 on dealer labor, tools and engine parts with no results. The FSM pointed to replacing the PCM, the dealer tech disagreed. I will have to make a decision to sell the car "as is", trade it in or live with this safety problem. No new DTCs.

Submariner409
03-15-14, 02:26 PM
An air leak - vacuum leak - will cause LEAN fuel trims - a leaking FPR or injector will cause RICH fuel readings.

ANY engine will experience some coolant temp rise while pulling up a hill - same as you sweat while jogging uphill. Normal.

(You should see how fast the coolant temp DROPS when doing a forced coastdown from 140 - as much as a 20 degree drop in 20 seconds in cool weather.)

ontarff
03-15-14, 09:06 PM
Yes, it does cool down on a coastdown quickly with the high idle condition. I think am going to reluctantly take the car back to the dealer for it's first radiator coolant drain, flush and refill to assure engine cooling performance. Maybe this will help? I will change the thermostat as well. I can't get to the stupid plastic (cheap) radiator drain petcock about 4" straight up, offset from the 1/2" hole in the metal frame support next to the radiator drain. How could GM engineer a car you can"t even easily drain the radiator??? Ridiculous PITA! Even getting to the lower radiator hose is not an easy task.

I can't find an air leak. Everything from the air filter to the air intake manifold has been triple checked. I will run another fuel trims test with my scantool and post it. Wouldn't a FPR or injector air leak be consistent at all engine temps? What about the fuel filter? I haven't changed it. Could it be restricting fuel flow causing a lean condition? When I did a fuel rail pressure check, it was good at 42 psi.

drewsdeville
03-16-14, 02:14 PM
I can't find an air leak. Everything from the air filter to the air intake manifold has been triple checked.

There might not be one. A faulty MAP or MAF signal can create scenarios that mimic them, however. This is where I was going next with the request in post 115...

ontarff
03-20-14, 09:28 PM
The MAP and MAF numbers are good. Here are the fuel trim numbers from a test today with a snapshot of what caused a MIL.

http://i1231.photobucket.com/albums/ee518/dmpierce/3-20.png (http://s1231.photobucket.com/user/dmpierce/media/3-20.png.html)

http://i1231.photobucket.com/albums/ee518/dmpierce/3-20FuelTrims.png (http://s1231.photobucket.com/user/dmpierce/media/3-20FuelTrims.png.html)

http://i1231.photobucket.com/albums/ee518/dmpierce/3-20LiveDataGraphIdle.png (http://s1231.photobucket.com/user/dmpierce/media/3-20LiveDataGraphIdle.png.html)

It seems as though the B1S2 O2 fuel trim sensor is not right @ 99%.

drewsdeville
03-21-14, 05:28 PM
These numbers are only under one condition - idle - which doesn't lead us anywhere (we already know you have a problem at idle). We need to know if the fuel trim numbers get better or worse under higher throttle/rpm/load to help guide us to the cause. Also need oxygen sensor voltage chart under wide open throttle (safely!).

ontarff
03-22-14, 01:00 AM
As you can see when the MIL triggered above, the engine was at 999 RPM. The high idle condition always triggers below 2000 RPM. I have to determine what the sensor parameters are for the B1S2 O2 sensor fuel trim. I can adjust the parameters so it doesn't show it pushed to 99%. Today the car ran well on 2 separate trips with warm restarts over 10 miles with no high idle condition. I need to get someone to drive the car while I record a WOT condition. There is a lot of idle surging on cold start after the RPM drop from 1200 RPM to 900. Is the PCM learning?

ontarff
05-02-14, 05:58 PM
I finally solved the problem. The problem only occurred on a warm restart so I knew the problem was engine temperature related. I decided to replace the engine coolant and thermostat to protect the N* to the best performance possible since the high idle condition caused the engine to run warmer than usual (See post #123). When the radiator hose was disconnected to replace the thermostat, guess what fell out? (See picture below)The intermittent high idle problem was caused by a failed thermostat that was in two separate pieces disrupting coolant flow. Since the coolant and thermostat were replaced the car runs great and purrs like a kitten with no idle problems. The FSM did not point to this condition causing this problem. The Dealer Technician was correct that it was not the PCM although he recommended replacing the TPS and tightening down the air intake manifold.

http://i1231.photobucket.com/albums/ee518/dmpierce/Thermostat.jpg (http://s1231.photobucket.com/user/dmpierce/media/Thermostat.jpg.html)

rodnok01
05-02-14, 06:36 PM
Well that's a weird find right there.... They are not known to go bad let alone break apart.