New IAC, SES light kicked on the next day.

krisking94

Member
Joined
Oct 6, 2014
As title states I replaced the IAC sensor. My car was having random stalling issues. Everytime that happened my iac counts would be off the charts (high 80's). Did some research says a faulty IAC will cause periodic stalling. Took the old sensor out, it was all black and you couldn't even compress the spring on it. Even tried to sandwich it between the ground with my hand to get it to compress and it did nothing. Put in the new sensor, dialed in my IAC at warm idle ( clt over 160 degrees, running a TT chip). Set my iac to about 20-22. Tps was right at .44. Car was running great but didn't really do drive cycle. Drove it around a bit, did some wot runs. Went back home put the car in park and iac was still reading at about 20-22. Everything seemed to check out fine. Leaving my girlfriends house this morning I start the car and everything seems fine. I didn't let the car fully warm up before I put it in drive (probably about 120 degrees, and no I didn't go dog on the throttle I was just cruising home). Put it in drive then SES light kicked on. Drove it home, didn't feel any issues. Park it at home iac wouldn't go down past 40 I even gave it about 5 min. Ses light is still on mind you. Shut the car off, turn it back on and then the light is gone. Let it in for about 5 min iac was reading about 20-22, occasionally it would jump up to 30. Shut car back off and that was about an hour ago. Does the car need to have a drive cycle done after a IAC change? I feel like the ses light came on for a reason. Should I disconnect the reconnect the orange power cable by the battery? Is my issue the iac or could it be something completely different? Last 2 months I have put a new ac delco fuel filter in, kirban fuel pressure regulator, deatscwerck 300 fuel pump and replaced my old ls1 maf with an apparent know "good ls1 maf" from a local Buick club member in my area.
 
A lot of times you can't "compress the spring" on an IAC sensor. It's a stepper motor driving a lead screw. What code is set in the computer? Retrieve the code before you disconnect the orange wire.
 
A lot of times you can't "compress the spring" on an IAC sensor. It's a stepper motor driving a lead screw. What code is set in the computer? Retrieve the code before you disconnect the orange wire.
Pronged the Aldl port, code 42 came up and that was the only one. That it was it stored. Light is not on anymore but it did come on for a short trip home this morning
 
I had a similar issue on my 86 T years back. I had thought the sensor went bad and replaced it with an AC delco sensor. Thought the issue was resolved but the SES light came on and sure enough it was a code 42.

I was battling this for a few days and even swapped the ECM. After did that it worked out for a couple of weeks.

Drove the car and I hit a pretty good sized bump. After a few mins the SES light came back on with the same code.

Checked all the connections by the IAC and all was fine.

Had the car running and Pulled the kick panel and removed the ecm from the kick panel and the SES light shuts off. It was the pin to the ecm wire which controlled the IAC that was coming out slightly. I was able to secure it and that solved the issue.

Hope this helps..
 
I had a similar issue on my 86 T years back. I had thought the sensor went bad and replaced it with an AC delco sensor. Thought the issue was resolved but the SES light came on and sure enough it was a code 42.

I was battling this for a few days and even swapped the ECM. After did that it worked out for a couple of weeks.

Drove the car and I hit a pretty good sized bump. After a few mins the SES light came back on with the same code.

Checked all the connections by the IAC and all was fine.

Had the car running and Pulled the kick panel and removed the ecm from the kick panel and the SES light shuts off. It was the pin to the ecm wire which controlled the IAC that was coming out slightly. I was able to secure it and that solved the issue.

Hope this helps..
Hmm so you remember what pin?
 
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