Question I am working on a Chevy Lumina Sedan for a friend of mine. She brought the car to me because the wngine was surging while stopped and in drive. Eventually the engine would cut off. Sometimes it would cut off as soon as she stopped. I checked the codes and it showed code 35 and 44. The 35 was for the IAC, so I checked the resistance on the pins. A-B showed 60ohms, C-D showed 60 ohms and there were no shorts between A-C and B-D. I then pulled the IAC off and it fell apart in my hands. So, I put a new one in IAW the manual and the car is now surging worse than before. I noticed that someone had been messing with the Idle set screw because the paint mark on it was cracked. As far as code 44 (I think lean mixture), I am not sure what to check. Do you have any ideas?
Answer
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IDLE LEARN PROCEDURE: Any time the battery is disconnected, the programmed position of the IAC valve pintle is lost, and replaced with a default value. To return the IAC valve pintle to the correct position, perform the following procedure:
After restoring battery power, connect the Tech 1 "SCAN" tool.
Select "IAC SYSTEM," then select "IDLE LEARN" in the "MISC TEST" mode.
Proceed with idle learn as directed.
This procedure allows the ECM memory to be updated with the correct IAC valve pintle position, for the vehicle, and provide a stable idle speed.
Without this procedure the idle will not stablize
sorry added pic for another question
