: Misfire and SES light



chasmanc
12-22-04, 12:29 PM
Recently purchased a 99 STS that just turned 76K. Have had problem with regular, heavy misfire especially on cold start. I drive half a mile and it seems to clear up. (SES light comes on). However, irregular misfire felt at stoplights at idle . Car serviced a Cad dealer. Cleaned injectors and only minor improvement. Can any one give me help on this one?
Chuck

chasmanc :cool:

mcowden
12-22-04, 03:01 PM
At 76k, it shouldn't be plugs or wires, but it could be. Have you ever had an O2 sensor replaced? Do you ever see any messages on the console when the SES light comes on? Have you checked for codes yet? Has the car had any issues fixed up to this point that you know of? Fuel rail recall done?

The codes will point you in the right direction. Hold down the "OFF" and Warmer (or passenger-side warmer) buttons simultaneously for a few seconds and be ready to write down the codes. They will show up on the console after the lights test. Expect the codes to look like P0300. They will be a letter followed by 3 numbers on a 96 or newer car. Write them all down and let us know. Someone will be able to point you in the right direction. When you see "PCM?" on the display, just press OFF a few more times to get back to normal display mode or turn off the ignition.

M C
:cheers:

JimD
12-22-04, 04:19 PM
This is how you display codes on a '99 Seville:






1998 - 2004 Seville ; On Board Diagnostics Display

You will use the 3 switches located to the right of the Driver Information Center (DIC) to activate and respond to the OBD prompts on the DIC.

ON/OFF = YES
INFO RESET = NO
INFO DOWN or INFO UP = manual toggle


Ignition ON, acknowledge any warning messages; press ON/OFF and INFO UP together for 2 to 3 seconds. Everything in front of you lights up for 4 or 5 seconds, then you will see:

Display shows "ALL?"

Answering YES will display "ALL CODES?"
Answering YES will run automatic test sequence and display codes, if any. Systems and codes will scroll faster than I am able to read them and write them; not to worry.
"ALL CLEAR CODES?" will display at the end of the automatic test. If you are satisfied you have the information you need, answer YES to clear/erase all error codes.


Answering "ALL?" with INFO DOWN will toggle systems test manually in order.
Answering "ALL?" with INFO UP will toggle system test manually in reverse order.

Press INFO RESET to reset DIC to "ALL?" to start again.

Ignition OFF to exit.


SYSTEMS: (as of 1998)

ABS (Antilock Brake System)
AMP (Amplifier)
DDM (Door Driver Module)
DIM (Dash Integration Module)
IPC (Instrument Panel Cluster)
IPM (Instrument Panel Module)
IRC (Integrated Radio Module)
PCM (Powertrain Control Module)
RFA (Remote Function Actuation)
RIM (Rear Integration Module)
SDM (Sensing and Diagnostic Module) Includes airbag crash data. Under RF seat
VTD (Vehicle Theft Deterrent)
MSM (Memory Seat Module)
TTM (Tilt/Telescoping Module)
RSS (Road Sensing Suspension)

chasmanc
12-22-04, 07:21 PM
Thanks, guys. I really appreciate your responses. Will try to access codes. I suspect it is P0300.
Tell me more about the fuel rail recall. Is this something recent? Remember this is a 1999 STS!
Concurrent problem has been "check coolant level" message, but I think i have that one resolved. (Loose hose clamp.)
Chuck

chasmanc
12-24-04, 05:28 PM
Ran thru codes sequence as described by Jim: significant code, I think is P0300. Did not want to erase codes, but did so inadvertenly. Will they reappear when engine is run and problem reoccurs? Anyway, what does this code mean and what is the remedy?
BTW, Still having "check coolant" message. (Refilling with water at this point)
Chuck

JimD
12-24-04, 06:48 PM
Ran thru codes sequence as described by Jim: significant code, I think is P0300. Did not want to erase codes, but did so inadvertenly. Will they reappear when engine is run and problem reoccurs? Anyway, what does this code mean and what is the remedy?
BTW, Still having "check coolant" message. (Refilling with water at this point)
Chuck


P0300 is telling you what you already know; misfire detected. And yes, it will return if the misfiring continues. A dealer with the proper tool can tell you which cylinder but not "why". Could be fuel or ignition related.

I would urge you to avoid adding straight water (or straight Dex-Cool) to the surge tank. Proper 50 / 50 mix is important. If you are adding a pint at a time, the loss is not serious. And if the level is not really dropping at all, you could have a bad "level" sensor.

Ranger
12-24-04, 07:15 PM
Thanks, guys. I really appreciate your responses. Will try to access codes. I suspect it is P0300.
Tell me more about the fuel rail recall. Is this something recent? Remember this is a 1999 STS!
Concurrent problem has been "check coolant level" message, but I think i have that one resolved. (Loose hose clamp.)
Chuck
Fuel rail recall was for the '95 -'97's. They replaced the nylon fuel rail with a stainless steel rail because they were starting to leak with age and it is a fire hazard (saftey issue). No one knows if the later models will eventually be added.

chasmanc
12-24-04, 10:27 PM
JimD,
Thanks for the feedback. Taking the car back to dealer on Monday for these two problems.
I have already repalced the water pump and the spark plugs.I guess next would be an injector (or injectors). Also considering a procedure jokingly called an "engine enema". Is this any different than what has already been done to clean the injectors? This souded to me like something more extensive...(?)
Hoses seem "soft" to me could that be the source of part of this problem? I thought I had solved the low coolant problem when I found the top radiator hose leaking and tightend the clamp. Then I went 5 days without getting the low coolant message. But it showed up again after the fifth day. Previously, It was only a day or two at the most before it showed up (after refilling). Last time I had to add one gallon to reach the "cold full" point. (the surge tank was EMPTY.)
Thanks for your continued interest and help.
Chuck

JimD
12-25-04, 01:05 PM
JimD,
Thanks for the feedback. Taking the car back to dealer on Monday for these two problems.
I have already repalced the water pump and the spark plugs.I guess next would be an injector (or injectors). Also considering a procedure jokingly called an "engine enema". Is this any different than what has already been done to clean the injectors? This souded to me like something more extensive...(?) ....

Chuck

Can't help much with injector cleaning; my injectors have sprayed something like 6,600 gallons of fuel without a problem. It is possible one of your injectors is failing and knowing which cylinder is missing will be important.

Your "engine enema" sounds like a combustion chamber carbon removal procedure ( I don't see the connection between a miss condition and carbon buildup inside the combustion chamber). You can easily remove any carbon buildup by heavy application of WOT until the cloud of crud is no longer seen in the mirror. Inexpensive and effective.

chasmanc
12-25-04, 02:21 PM
Can't help much with injector cleaning; my injectors have sprayed something like 6,600 gallons of fuel without a problem. It is possible one of your injectors is failing and knowing which cylinder is missing will be important.

Your "engine enema" sounds like a combustion chamber carbon removal procedure ( I don't see the connection between a miss condition and carbon buildup inside the combustion chamber). You can easily remove any carbon buildup by heavy application of WOT until the cloud of crud is no longer seen in the mirror. Inexpensive and effective.
What is WOT?
C.

JimD
12-25-04, 03:34 PM
= Wide-Open-Throttle.

Find a safe place to be doing this and from a rolling 35 - 40 MPH with gear selector in 2nd gear, floor the throttle and it should downshift to 1st gear. Let the computer handle the 1 - 2 upshift at max RPM and keep winding until as close as you can get to 70 - 75 MPH.

Then let off on the throttle completely and let the engine compression brake back down to 35 - 40 MPH. Repeat until you do not see a cloud of carbon in the mirror.

You will be doing the combustion chambers a favor. Repeat frequently and regularily.

chasmanc
12-25-04, 06:41 PM
= Wide-Open-Throttle.

Find a safe place to be doing this and from a rolling 35 - 40 MPH with gear selector in 2nd gear, floor the throttle and it should downshift to 1st gear. Let the computer handle the 1 - 2 upshift at max RPM and keep winding until as close as you can get to 70 - 75 MPH.

Then let off on the throttle completely and let the engine compression brake back down to 35 - 40 MPH. Repeat until you do not see a cloud of carbon in the mirror.

You will be doing the combustion chambers a favor. Repeat frequently and regularily.
Jim,
THIS is something I have wanted to do. There is a relatively sparsely traveled Interstate in southern AZ that we have yet to travel this winter. Will schedule a trip in that direction soon and will try your remedy.
The coolant loss still bothers me. I'm guessing that there may be a more serious problem than a leaking hose: bad head gasket(?) I'm led in that direction because these two problems may be related (with coolant getting in to foul a cylinder.) Plauseable?
Thanks for your continued interest!
Chuck

JimD
12-25-04, 10:16 PM
Be sure to keep one eye on the temp. gauge during the WOT if you suspect coolant loss through a head gasket. The high compression pressure and vacuum developed during WOT and compression braking will certainly test your head gaskets.

Carry a gallon of premixed 50 / 50 water - Dex-Cool with you.

You said in an ealier post the car had been serviced by a Caddy dealer. Try to confirm the coolant was replaced / refreshed when the car hit 5 years in service.

chasmanc
02-09-05, 11:39 PM
SPECIAL TO JIM D
Jim:
To make a long story short, the problem was a head bolt that "pulled out". Coolant was getting into the number 1 cylinder. My choices were: 1) try repairing the damaged thread (helicoil) which I was told was not always successful; 2)junk the engine and replace it (with a new engine); 3) take a big 'hit' and trade it in "as is" on another car. Since the car was one that was in otherwise good condition and was VERY attractive (red with gold trim and Vogue whitewalls), I opted for the new engine. I am VERY pleased with the outcome. However, my $8000 car has now cost me in excess of $14000!
Anyway, all is fine now except for spending all that money!
Thanks for your help along the way. Hope this helps some other Cadillac owner out there!
I also own a 2001 SLS (purchased new) that has an engine that was replaced (by Cadillac) after several unsuccessful fixes on the original engine. They never revealed the problem to me but I suspect it was a piston problem... It made an AWFUL racket!
My other ride (my favorite by far) is a white 1987 Corvette Coupe with about 75,000 miles. Runs and looks like a million!
Regards to all.
Chuck

turbojimmy
02-10-05, 06:21 AM
I wonder what they'll do with your car? My car is a flood total that was on a dealership lot when the flood rolled through. When I did the title search on it, I found that it had evidently been to the dealer numerous times in August and September of '04 for "electrical work". Suddenly the title changed hands and it was for sale at the dealer. Flood rolled through in mid-Sept. The dealer was wiped out from the the flood and is no longer around so I can't ask what it was in for.

I don't have any electrical issues (knock on wood), but then I've replaced nearly everything electrical.

My P0300, as it turns out, was caused by a bad coil pack on the right side of the engine.

Jim