Pontiac Problems? Ask a Mechanic for Answers ASAP
Hi my name is***** to JustAnswer.
Sounds like a bad map sensor. When it is unplugged the ECU runs the default algorithm instead of using the map sensor reading. Even if you plug it back in during that drive cycle the ECU will not use it until the vehicle is restarted. I would double check the wiring harness for any damage to the MAP circuits. If that checks out I would replace the map sensor. I will provide you with a diagram of the MAP sensor circuit.
Did you check the signal wire to the map sensor from end to end? It should have 0 ohms from the PCM to the MAP sensor. It is the light green wire. On the PCM side it is the Clear connector. I will provide the pin location in the picture.
As in OL or 0 ohms?
I would run a new wire from the MAP sensor to the PCM and see how it runs. Sounds like a short in the signal wire
As a last effort before I say it needs a PCM. Did you check the 5v reference on the grey wire while it was running? I would try that first.
Leave the map sensor plugged in and unplug the MAF sensor. See if it starts
Okay, maybe we just have a large vacuum leak. Have you started it and sprayed carb cleaner around the intake or other vacuum sources?