: 1997 deville stalling at idle

06-13-09, 08:12 PM
My 1997 base DeVille had a P0741 code and I thought the stalling at a stoplight was due to the TCC was bad. But mow after the TCC has been replaced I still have the stalling problem. It will stall at a stoplight even when I put it in neutral. Now the car is stalling when I'm moving at very low speeds.

I searched this forum and found a thread that discussed the IAC motor. I'm looking at the intermittent failure so the motor resistance should be higher than normal...

My questions are:

What is the normal resistance measurement?
Is there anything else I should check?

As of right now I have no current codes.

Thanks in Advance!

06-13-09, 09:03 PM
Do a good TB cleaning first.

06-21-09, 02:10 PM
I cleaned the throttle body and IAC motor, but I still get stalling at low RPMs. It doesn't matter if I'm in gear or neutral, it stalls just the same.

06-21-09, 05:33 PM
Are you sure that the IAC air circuit is clear?

06-25-09, 02:37 PM
I'm not sure what you mean by the IAC air circuit. Pardon my ignorance :thepan: I did replace the IAC motor yesterday and it ran great for the rest of the day - but today at lunch it stalled a couple of times at idle. It did rain this morning, I'm not sure if that is important.

How do I check the idle air circuit?

06-25-09, 03:03 PM
The IAC circuit is just an air channel that bypasses the throttle plate and is controlled by the IAC valve. There should be two holes in the inside of the TB. One before the throttle plate and one behind it.

06-25-09, 03:23 PM

I'll pull the IAC off and take another look in there. I cleaned it out the best I could with throttle body cleaner but there still was some black in there. Maybe I'll throw in some seafoam - someone in this forum had some good luck with it.

06-25-09, 10:11 PM
Ahh, forget the snake oil. All you need is carb or TB cleaner. Scrub it till it is clean. If the IAC circuit is carboned, clean it out and spray the cleaner in there.

06-26-09, 10:19 AM
I pulled the IAC off and the parts I see look clean, but I stuck a Qtip in there sprayed with throttle body cleaner and it came out black. I repeated the procedure using over 30 Q tips.... I think I'm going to have to take the throttle body off to get the thing really clean. I'll let you know how it turns out.

06-26-09, 10:45 AM
Don't go through all that work. Spray the cleaner in and if you see it come out inside the TB bore, then the passage is open.

06-26-09, 11:52 AM

It's open then, but very dirty. After it's clean, what should I look at next if it stalls?

06-26-09, 06:13 PM
Did you ever verify if the IAC motor was actually working or not? Can you keep it running with your foot on the accelerator?

06-27-09, 10:07 PM
i have a 1993 elderado doing the same thing it stalls at 207 degrees at idle shop says its the computer but it's been replaced 3 times and still have the problem any ideas?

06-29-09, 10:28 PM
Did you ever verify if the IAC motor was actually working or not? Can you keep it running with your foot on the accelerator?

I assume it's working because right after I replaced the IAC the car would almost stall out, and then the car would rev up to about 950 to 1000 rpm, then settle out to about 625 to 650 rpm.

The car ran ok for a couple of days, but today it stalled 4 times while waiting in line at a drive through.

The stalls seem to come out of nowhere; meaning there is no warning before they occur. I don't know if the car would stall if I were to give it gas, but I doubt it would. All of the stalls so far have occurred while my foot was off of the gas. And they seem to be more likely after the car has been rained on.

06-29-09, 10:35 PM
Still no DTC's?

06-30-09, 12:52 AM
It could be a bad spot in the TPS (Throttle Position Sensor)... I don't have the test procedures off hand though. DTC's would be nice too.

06-30-09, 06:28 AM
Current DTC's are P0741 and B2146. I don't believe the P0741 is the cause of the stalls because the car will stall when it is in neutral or in park. The other strange thing about my P0741 code is that I'll clear the code, and the check engine light will still pop back on even when I'm in 3 instead of overdrive.

I have the DIY Alldata database for my car, it mentioned a procedure to reset the IAC. I'll try that this morning. The only other thing I can think of is replacing the battery. When I got my oil changed the tech said my battery voltage was low, and the alldata site mentioned one of the inputs for the IAC control function was battery voltage. I'm also assuming my battery is getting worse because in the last couple of days or so the clock on my radio stopped keeping accurate time. :annoyed: I would reset it but as soon as I shut the car off the clock would loose the time again.

07-01-09, 06:01 AM
Hmmm..... Come to think of it, Before I swapped the engine/tranny/PCM in my 94 eldo, I was getting a TCC stuck off code intermittently. Whenever the code come up, the car ran like crap. It was misfiring and just plain running horribly. But what i'm getting at is, I wonder if the car goes into a certain mode when that code is present which may be causing your symptoms.

Edit: Nevermind... was reading more on the code, I'll just copy/paste.

Circuit Description

The PCM controls the torque converter clutch (TCC) solenoid valve pulse width modulation (PWM). The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is applied, the engine is coupled directly to the transmission through the TCC. The TCC slip speed should be near 0. If the PCM detects high torque converter slip when the TCC is commanded ON, then DTC P0741 sets. DTC P0741 is a Type B DTC.

Conditions for Running the DTC

* No MAF DTCs P0101, P0102, or P0103.
* No TIP DTCs P0121, P0122, or P0123.
* No VSS DTCs P0502, or P0503.
* No A/T Input (shaft) Speed Sensor (ISS) DTCs P0716, or P0717.
* No TCC Stuck ON DTC P0742.
* No Transmission Fluid Pressure (TFP) manual valve position switch DTC P1810.
* No TCC PWM solenoid valve DTC P1860.
* The engine run time is greater than 5 seconds.
* The engine is not in fuel cut off.
* The TFP manual valve position switch indicates D4.
* The transmission gear ratio indicates 2nd, 3rd, or 4th gear.
* The transmission fluid temperature is -18-130C (0-266F).
* The throttle angle is greater than 8 degrees.
* Delivered torque is between 43-202 N.m (32-150 lb ft) .
* The TCC solenoid valve is commanded ON at maximum duty cycle.

Conditions for Setting the DTC

TCC slip speed exceeds its limit for a given torque for 5 seconds.

Torque (lb ft) Slip Speed Limit (RPM)
32 72
64 88
96 200
128 248
160 256

Action Taken When the DTC Sets

* The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
* SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the driver information center (DIC).
* The PCM inhibits TCC engagement.
* The PCM inhibits 4th gear if the transmission is in hot mode.
* The PCM stores DTC P0741 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

* The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
* A scan tool clears the DTC from PCM history.
* The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
* The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

* Inspect the transmission fluid level.
* The transmission may be in hot mode. Inspect the transmission fluid lines to the radiator. The lines may be pinched, plugged or twisted.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. This step inspects the transmission fluid to ensure that it is at the proper level.
3. This step verifies that the TCC engages when commanded ON by the scan tool

To test the TPS, use an ohmmeter and probe the terminals where the gray and dark blue wires would go into the sensor. When the throttle plate is closed it should read a high amount of ohms. As you open the plate it should read less and less ohms. If, as you're opening the plate you see the ohms spike, you have a bad spot in the sensor.

07-03-09, 10:59 AM
Reprogramming the IAC seemed to do the trick. It did stall a couple of times right after I reprogrammed it, but it hasn't stalled since. According to ALLData you don't need a scanner to reprogram it; on a 97 you turn the key to the lock position for 30 seconds from the off position. The coolant temp has to be above 100 deg F when performing this by the way - once the 30 seconds has passed turn the key back to off. And that is it.