92 Regal 3.8 codes 42,43

[lgrouper03]

I am new to this forum. I am hoping to tap into some of the knowledge that resides on the forum. I have a 92 Buick Regal with the 3.8L. I am getting an occasional "check engine soon" light. There doesn't appear to be any discernable pattern as to when this thing comes on. The car runs perfectly, based on the small amount that I drive the car. Last night I got the codes from the computer. The sequence read as follows: 12,12,12,42,42,42,43,43,43,12,12,12, etc. (repeat). I thought that each diagnostic code was supposed to be separated by a 12. Does anyone have any ideas as to why the 42 and 43 flashed consecutively? And my last question: Does anyone, from prior experience with these cars, know what the faulty part could be? All I know right now (according to the info I have) is that the fault is somewhere in the Electronic Spark Timing Circuit.

Thanks.

[Hypsi87]

Originally Posted by lgrouper03

I am new to this forum. I am hoping to tap into some of the knowledge that resides on the forum. I have a 92 Buick Regal with the 3.8L. I am getting an occasional "check engine soon" light. There doesn't appear to be any discernable pattern as to when this thing comes on. The car runs perfectly, based on the small amount that I drive the car. Last night I got the codes from the computer. The sequence read as follows: 12,12,12,42,42,42,43,43,43,12,12,12, etc. (repeat). I thought that each diagnostic code was supposed to be separated by a 12. Does anyone have any ideas as to why the 42 and 43 flashed consecutively? And my last question: Does anyone, from prior experience with these cars, know what the faulty part could be? All I know right now (according to the info I have) is that the fault is somewhere in the Electronic Spark Timing Circuit.

Thanks.

That controls the timing retard on your car. if that is faulty it pulls like 12 or 13 some degrees of timing out. Check the ESC module *sp*. That was doing that to my car and I could not figure it out. It turned out to be that my ESC module was not there! My uncle had stole it a year ago to replace the bad one on his TTA. Apart from that that is about the extent of my knowledge on that. Here is some info in thoes codes that i have written down.


code 42

Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.

During cranking, the timing is controlled by the ignition module while the ECM monitors the engine speed. When the engine speed exceeds 400 RPM, the ECM sends a BYPASS signal to the ignition module which switches the timing to ECM control. The ECM calculates what the timing should be then "tells" the ignition module via the EST circuit.

An open or ground in the EST circuit will stall the engine and set a Code 42. The engine can be re-started but it will run on ignition module timing.

The conditions for setting this code are:

System in BYPASS mode but the ignition module is still controlling timing

- or -
Engine speed > 600 RPM with no EST pulses (ECM controlled timing) going to the ignition module for 200 msec.



Typical causes for this code include:

1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM

code 43

Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit.

ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. A knock sensor (located at the rear of the engine block) sends signals to an ESC module which then signals the ECM that knocking is being detected. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and may possibly result in engine damage, if there is detonation.

Loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. This results in sluggish performance and a Code 43.


The conditions for setting this code are:

Engine is running
ESC input signal has been low more than 2.23 seconds



Typical causes for this code include:

1) Open or shorted knock sensor
2) Loose knock sensor
3) Excessive mechanical noise within engine
4) Improper or incorrectly installed PROM or CALPACK in the ECM or defective ECM
5) Intermittent open in the EST line to the ignition module

[lgrouper03]

Thanks for the feedback. I am going to ask an ignorant question now. I have done very little work on this car other than typical maintenance and repairs. Where is the "ESC module"? I'm guessing that this is what I would call the "coil pack", where the 6 individual ignition coils are. I just want to make sure we are talking about the same thing.

[Hypsi87]

No question is a stupid question. The ESC mod. is a little thin little retanglar thing. I think it is on the left fender wall. (Im not sure on that thought.) Maybe flatrater can shed some light on this

[Flatrater]

The ESC is part of the ignition module mounted under the coil paks.

The 2 things I have seen cause this problem are the ECM and ignition module. My first guess would be a bad ECM, back in those years GM had a bunch of bad ECM's with certain part numbers I can't remember the bad part numbers but I would always replace the ECM first.

If you have a 3.1L engine make sure you do the IAC relearn procedure or you will get an idle stall problem.

[lgrouper03]

Thanks alot for the info! I feel like I am on the trail thanks to your input. Recently I have noticed some symptoms that I believe are associated with the check engine light being illuminated. Sometimes, and I repeat sometimes, the car will stutter a little bit right after it is started. On other occasions, it will die immediately after being started. If it dies, it always starts right back up and runs fine. I think this is exactly what Hypsi87 mentioned in an earlier post where he provided the code interpretations:

"An open or ground in the EST circuit will stall the engine and set a Code 42. The engine can be re-started but it will run on ignition module timing."

So, Flatrater (or anyone else who knows), given this added info, would you still recommend replacing the ECM? I'm not questioning your judgement at all - just trying to pin this thing down as much as possible before any money is invested.

Thanks again.

[lgrouper03]

Well, I replaced the ECM. No change - check engine light still on. I then replaced the ignition module. STILL, the check engine light is on. I have stopped dumping money at this point. I went ahead and pulled the codes once again. Now the code 42 is gone, but the code 43 remains. Any ideas? I could replace the knock sensor, but I'm afraid to dump more money after my recent experience.

[Hypsi87]

did you replace the ingnition module or the EST module? a code 43 is the EST circuit. A bad knock sensor WILL not throw a trouble code. so it is not that.

[lgrouper03]

I did as Flatrater recommended a couple of posts earlier - replaced the ignition module (which includes the ESC) and the ECM. If I understand correctly, the EST designation that you mention is general in nature - referring to the Electronic Spark Timing Circuit. If there is a EST module, I am unaware of it.

[Hypsi87]

Yes, their is a EST module for the EST circuit. 99% of the time when a code 43 is thrown, that is the problem. Im not to sure where it is located on your car though. I will see if I can figure it out

[jeepguy1]

im thinking possibly a crank position sensor i believe it has one but i wouls check a haynes manual at a auto parts store .

[dove-7]

I grouper, try having your knock sensor changed. This should reslove your problem. I had the exact same problem on my Regal. But the light stayed on, only to find out that the wire that connects to the sensor plug was a bad wire. After that problem was resolved, my car perofrmance was fine and the light went out.

[lgrouper03]

Thank you very much for the suggestions. The air conditioning compressor recently bit the dust and some of the rear suspension grommets are rotting out - causing a "jillopy" squeaky noise. Also as I was examing the engine wire harness in search of the "check engine" culprit, I noticed that the plastic protective wire loom crumbled to the touch. Furthermore, the wiring insulation itself was drying out and flaking off in some areas. I didn't find any areas that I thought could be causing a problem YET, but as I examined the car I noticed several future problems. So I replaced the car with a V6 Camry. My wife has one and it has been a wonderfully reliable car.