Now before I explain the problem I admit yes this is a J-Body GM, but I have 2 other G-Bodies and have had good luck with this forum in the past. The car in question is a 1988 Chevrolet Cavalier Z24 Convertible, with a 2.8L direct fuel injected engine with a little over 106,000 miles on it. About 2 weeks ago I pulled out of my driveway and went about a quarter of mile down the road and stopped at a stop sign, the car had a very rough idle surged very high and stalled out, I shifted into park and tried starting the engine it consistently cranked over but would not engage. So I had AAA tow the car to my shop, we replaced the fuel filter and cleaned out the Throttle Body it had a slight improvement, we replaced the Throttle Position Sensor adjusting it to factory GM spec voltage it made a slight improvement again.
Today we replaced the Idle Air Control Valve which upon removal found the old IAC to be sticking and loaded with carbon build up and the vehicle had a real big improvement in overall performance and idle surging reduced after replacing the IAC valve. However it still has a very small surge from idle but much less than originally. When I pulled the vehicle out of the garage and into the shop parking lot, I drove it around and simulated a stop at a stop sign when I did that it idled a little rough and stalled out; however this time when I put it in park and attempted to restart the engine it started up relatively easier than when this first started a few nuna, nuna, nuna and it kicked over shifted into drive and drove fine. I simulated this stop sign scenario again, and again it stalled out at a complete stop from a hesitant idle shifted into park and restarted the engine again with a few nuna, nuna, nuna and it turned over I parked it and have now returned to the drawing board. I suppose it could be clogged or dirty fuel injectors but I don't think it's a fuel related problem because as long as the car doesn't come to complete stop the engine won't stall.
The part I cannot understand is regardless of the fact that this car is OBD1 it hasn't thrown any kind of code, neither before or after any repairs. Only a check engine light when it stalls, after it restarts no lights, no codes. I have a GM Tech 1 but the ECM doesn't give me any troubleshooting codes to read or work with. This particular engine even though it has a Throttle Body does not have a Mass Air Flow Sensor so that rules that out, I already replaced the Idle Air Control Valve, Throttle Position Sensor, and Fuel Filter which all have made a significant improvement in overall performance but haven't solved the stalling at idle at a complete stop. So any thoughts would be greatly appreciated. Thanks
Today we replaced the Idle Air Control Valve which upon removal found the old IAC to be sticking and loaded with carbon build up and the vehicle had a real big improvement in overall performance and idle surging reduced after replacing the IAC valve. However it still has a very small surge from idle but much less than originally. When I pulled the vehicle out of the garage and into the shop parking lot, I drove it around and simulated a stop at a stop sign when I did that it idled a little rough and stalled out; however this time when I put it in park and attempted to restart the engine it started up relatively easier than when this first started a few nuna, nuna, nuna and it kicked over shifted into drive and drove fine. I simulated this stop sign scenario again, and again it stalled out at a complete stop from a hesitant idle shifted into park and restarted the engine again with a few nuna, nuna, nuna and it turned over I parked it and have now returned to the drawing board. I suppose it could be clogged or dirty fuel injectors but I don't think it's a fuel related problem because as long as the car doesn't come to complete stop the engine won't stall.
The part I cannot understand is regardless of the fact that this car is OBD1 it hasn't thrown any kind of code, neither before or after any repairs. Only a check engine light when it stalls, after it restarts no lights, no codes. I have a GM Tech 1 but the ECM doesn't give me any troubleshooting codes to read or work with. This particular engine even though it has a Throttle Body does not have a Mass Air Flow Sensor so that rules that out, I already replaced the Idle Air Control Valve, Throttle Position Sensor, and Fuel Filter which all have made a significant improvement in overall performance but haven't solved the stalling at idle at a complete stop. So any thoughts would be greatly appreciated. Thanks
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