I keep reading the IAC adjustment steps and most say keep the diagnostic terminasl A and B grounded with a jumper wire with the ignition on.

tehn after all is said and done after turning on the engine and doing the min. air adjustment. it says turn off the car and remove the jumper wire or other way around.

I'm afriad this will ruin my ECM and I want a few people on here to tell me yes do not start engine with the terminals A and B connected or no its ok to have the engine running with the jumper wire in there to do the adjustment.


Please just someone tell me straight out yes or no if its ok and why.

Thanks

 

I looked in my svc manual about the IAC and there are pages of stuff, but the main idea is that the IAC is controlled by the ecm and that only micro adjustments are necessary if ever. Grounding the ALDL in the on position resets the IAC to a basic setting and the the ecm will adjust it from there. They talk about using a scan tool to record the # of counts in codes. Basically though what GM says is that if the idle is too low, like 450 or less in drive to look for vacuum leaks, and also to look for a dirty, rich exhaust. If you need I could probably copy some of this stuff. They go on to say not to force the valve body in or out by hand, only electrically, ck for valve sticking in the bore, and/or a fouled valve that needs cleaning or replacement.

 

yea my idle kinda stumbles and then once car warms up it settles and idle iss consistant around 900-1000 but idk if thats an okay idle or what.

plus for my own curiosity would grounding the terminal wirth the engine on screew things up? not to drive it but in park? just curious because even tech articles on this site mention to ground it while unplugging the IAC but i cant keep the car running with the IAC and timing wire disconnected so i cant do the adjustment

tehy say you should do the adjustment when you buy a new IAC well I bought a new IAC

 

900-1000r's sounds a bit high but I guess that depends on what mods you've got. I think I would set the timing first, reconnect and clear the timing wire fault, then do the IAC. Personally I would do the IAC with the key in the run position to clear faults, then start the car and see how it idles. The ecm will set the IAC and you could see where it ends up. Then you could make an in or out adjustment on the IAC. Then replug it and see what it does. Gotta go to work now...

 

yea i know its a bit high. i'll figure it out just curious why the car will just die instantly with no iac and timing wire connected