89 old cutlass ciera 3.3 A/T. Has intermittent stalling problem. No SEL light and does not matter if it is hot or cold sat overnight or for a few hours it just starts stalling like it is starving for fuel/spark and will make a small backfire sound out air intake. It does not do it every time I drive sometimes it takes days to act up other times it stalls everyday. I have replaced fuel filter TPS MAF IAC Coolant temp sensor pcv valve Ignition module under coil packs crank sensor and fuel pressure regulator and has no hissing sounds like having a vacuum leak. Had fuel pressure tester on it when it stalled and had around 40 PSI. I also unplugged what I think is the torque converter clutch solenoid in the front of the trans close to side cover and it would still stall after unplugging even in 3rd and 2nd gear it would still stall. I also read and did this after it would stall I would get out and unplug 1 injector at a time and each time I did it would stall so id plug that one back in unplug another and repeated till all 6 were done still had the stalling problem. I finally checked for codes and 12 came up which is normal and then 29 came up and is a "quad driver module (computer) 4th gear circuit" What will fix this and can that cause the stalling? I read that it could be an ECM causing the stalling. I should also note I went through and unplugged all sensors under hood during the stalling and that did not help as it still stalled. I would like to know if the TCC is failing would it trigger the SEL light to come on as when i unplug that one it does not come on but unplugging the other sensors triggers the SEL light. Please help me if you can. Thanks.
Update:CAR ONLY HAS 88,000 ORIGINAL MILES ALSO.
Answers & Comments
Verified answer
Good God, that's awful. I won't be much help without laying eyes and ears on it, but a backfire up the intake and stalling sounds like your timing is off a ways.
Best of luck!
Not your TCC. Unplugged it won't ever "activate", and stick, which is what happens when they do fail. Typically you'd see the problem after cruising on the freeway, and come up to a stop light. Exactly like driving a manual transmission and forgetting to push in the clutch.
That quad driver error is odd, I would google for others with same problem and see what some people familiar with that specific vehicle have to say.
I personally doubt timing, that is a "static" setting which if a problem, should be consistent. Not always, but normally.
40 PSI sounds low, back then the GM standard was typically 47PSI for a multi-injector setup. It's a very basic system, depending on what that code 29 can be influenced by, low fuel pressure (thus starving the engine) could be a possibility. This is an OBD1 system, so it's relatively "stupid", with fewer codes, which means a code can be triggered by something seemingly not indicated specifically by the code.
I doubt it's the ECM (again unless that code specifically points to solely a failed ECM) if it were an ECM problem it would also likely be consistent, especially with no change hot/cold.Normally intermittents in electronics are worse or better depending on temperature, or simply fail catastrophically. GM had no inherent problems with their ECM's back then, most replaced are done so because people are just guessing at the problem.
89 Cutlass Ciera