Crazy IAC numbers

Caleb W.

Member
Everything is up to operating temp. (170 after a 10 minute drive on a cold day) In drive IAC counts are reading 175, in park they read 0. Idle in drive is around 800 (what the chip is programmed for) and in park it hovers around 1050. Correct me if I'm wrong but the IAC numbers increase when its adding air to keep the engine running. So the lower numbers mean its working less (in my case not at all) to keep the engine running. My question is what could be causing that massive fluctuation in IAC counts? TPS is at .44 at idle btw. I'm thinking just a simple re-adjustment might fix it but I started second guessing my self with that high of a difference.
 
Clean the IAC and see if that fixes issue. Do you have any codes? If you have another IAC, I would change and reset it.
 
Clean the IAC and see if that fixes issue. Do you have any codes? If you have another IAC, I would change and reset it.
Nope, no codes. I cleaned about a year ago. I guess I'll buy another one and put it in they aren't expensive. Would you recommend even attempting resetting/adjusting it?
 
OP,
Your understanding is correct. Don't confuse TPS voltage with IAC setting. These two are interdependent.

Sound like the minimum throttle is too low/closed. Reset the IAC and tps.
 
Around what number should I make a goal for the IAC? From what I've read I should get it around 20. Now for the actual adjustments, I adjust the throttle blade screw to get the IAC dialed in first then adjust the TPS to .42-.46v, and rinse and repeat until it's good? And do I do these adjustments in gear or in park?
 
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Welp, the adjustments did nothing. I'm assuming a vacuum leak? Are there vacuum lines behind the dash? I've replaced all lines in the engine bay with no result.
 
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