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IAC valve/sensor

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Old Nov 11, 2017, 09:45 PM   #1
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IAC valve/sensor

What’s up everyone,
I have a little question and hoping that the community can help me out. So I think my IAC is going bad. With my biss screw closed all the way my car isles at 1500 rpm and I get a check engine light saying the iac idle is too high and when I’m driving and just put the car in nutural I get idle bound from 700 to 1200 rpm and when I come to a complete stop my rpm goes back to 1500. Anyway I know the part is 300 and some change at the dealer what do you guys suggest I do? I was searching and came across this thread
https://www.evolutionm.net/forums/ev...ge-my-isc.html
Sorry for using your threat just need a reference anyway to make a long story short I called autozone to see if they even carry anything for the evo or the Chrysler. So I called and they do have them. I know everybody will always say OEM is the best but 300 plus isn’t easy to spend on a such a small peace lol. So the one at autozone is 242 dollars but has a life time warranty. Has anybody used the one from autozone? If so any pros or cons? Don’t want to spend 242 if I have to warranty it every month.
Thanks in advance everybone.

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Old Nov 14, 2017, 08:59 AM   #2
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you shouldn't be adjusting your BISS screw without also tuning the car in the process. It's not a carbureted car where you adjust idle and low speed screws and such for tuning. there's some process you have to do for setting the idle on the car and adjusting biss

Spend the money and buy OEM. saving $60 for autozone isn't worth it. if the thing were like $50 with a lifetime warranty maybe.

I went through three amazon ones (purchased one and two warranty returns) before buying OEM
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Old Nov 14, 2017, 09:55 AM   #3
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Quote:
Originally Posted by llDemonll
you shouldn't be adjusting your BISS screw without also tuning the car in the process. It's not a carbureted car where you adjust idle and low speed screws and such for tuning. there's some process you have to do for setting the idle on the car and adjusting biss

Spend the money and buy OEM. saving $60 for autozone isn't worth it. if the thing were like $50 with a lifetime warranty maybe.

I went through three amazon ones (purchased one and two warranty returns) before buying OEM
This. Went through two non-OEM before buying OEM. Should have just bought the right one to begin with.
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Old Nov 14, 2017, 11:35 AM   #4
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Quote:
Originally Posted by llDemonll View Post
you shouldn't be adjusting your BISS screw without also tuning the car in the process. It's not a carbureted car where you adjust idle and low speed screws and such for tuning. there's some process you have to do for setting the idle on the car and adjusting biss

Spend the money and buy OEM. saving $60 for autozone isn't worth it. if the thing were like $50 with a lifetime warranty maybe.

I went through three amazon ones (purchased one and two warranty returns) before buying OEM
Ok so here is the problem. i just tuned my car and my tuner closed the Biss screw all the way but yet my car is still idle high. i was told by my tuner that either my throttle body is leaking or my IAC is bad. my TB is a milspec 65mm which has maybe 1k miles on it and IAC i dont know. i did a test where i removed the IAC turn the key on and nothing happens not sure if thats a sign or not.
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Old Nov 14, 2017, 11:38 AM   #5
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Do a boost leak test and pay extra attention to the biss screw and other throttle body seals. If those are leaking then thats likely causing your problems. My Biss screw O-ring had basically disintegrated and i caught it on the last boost leak test.
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Old Nov 14, 2017, 01:49 PM   #6
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Quote:
Originally Posted by benIX View Post
Ok so here is the problem. i just tuned my car and my tuner closed the Biss screw all the way but yet my car is still idle high. i was told by my tuner that either my throttle body is leaking or my IAC is bad. my TB is a milspec 65mm which has maybe 1k miles on it and IAC i dont know. i did a test where i removed the IAC turn the key on and nothing happens not sure if thats a sign or not.

"my tuner".....that's the problem.

Why didn't he fix it?



The quick check is to remove the IAC but leave the wires connected.
Turning on the key will make it drive one way then back again.
Turning the key off does a similar thing.


If it doesn't drive then remove it altogether and check the resistance of all 4 coils which should be the same.........there's more than one model but the older ones are about 30 ohms each.


Swapping parts around is the worst thing to do because you end up with even more problems.


The usual problem is one coil open circuit, in that case it doesn't drive but oscillates.
If it does nothing at all then it might be seized (common with water injection) or there's a wiring problem.

Last edited by RightSaid fred; Nov 14, 2017 at 01:59 PM.
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