[Help] IAC value for 1990 L98
Thread Starter
Racer
Joined: May 2000
Posts: 334
Likes: 0
From: Fort Wayne Indiana
Cruise-In II Veteran
[Help] IAC value for 1990 L98
Could somebody explain the IAC valve to me?
A little background: Stock L98 with 22k miles. I was getting a code 45 (rich oxygen sensor) at sustained speed over 70 mph. The original plugs, cap and rotor were replaced as well as the oxygen sensor last week. I cleared the codes and and the car is running well now. A friend gave me a Snap-On MT2500 scanner and said this will help get everything right. I checked the scanner values against my Helms manual and everything is within range except the IAC value. The IAC Learned Value is 40, however the actual IAC value moves between 58 and 63.
The service manual says the IAC value should be between 5 and 50. The scanner says values less than 20 are best. I used the IAC valve reset technique several times and the value doesn't change. If I unplug it, it goes up to 160.
What do I need to do? Is the valve bad and in need of replacement? My concern is that I can't get the IAC down to the 5-50 range. What does all of this impact?
Thanks for your help ;)
Pete
A little background: Stock L98 with 22k miles. I was getting a code 45 (rich oxygen sensor) at sustained speed over 70 mph. The original plugs, cap and rotor were replaced as well as the oxygen sensor last week. I cleared the codes and and the car is running well now. A friend gave me a Snap-On MT2500 scanner and said this will help get everything right. I checked the scanner values against my Helms manual and everything is within range except the IAC value. The IAC Learned Value is 40, however the actual IAC value moves between 58 and 63.
The service manual says the IAC value should be between 5 and 50. The scanner says values less than 20 are best. I used the IAC valve reset technique several times and the value doesn't change. If I unplug it, it goes up to 160.
What do I need to do? Is the valve bad and in need of replacement? My concern is that I can't get the IAC down to the 5-50 range. What does all of this impact?
Thanks for your help ;)
Pete
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: [Help] IAC value for 1990 L98 (Blazer)
The Idle Air Control valve does just that, it controls idle speed. If you have no problem with idle steadyness nor speed, leave it alone.
Sometimes cleanind the TB bore and the IAC bore and pintel corrects an idle problem, but if no issue other than reading value, leave it alone.
Sometimes cleanind the TB bore and the IAC bore and pintel corrects an idle problem, but if no issue other than reading value, leave it alone.
Le Mans Master
Joined: May 1999
Posts: 6,515
Likes: 1,301
From: Windermere FL
Re: [Help] IAC value for 1990 L98 (Blazer)
Blazer,
65 is correct, if your idle is fine leave the IAC alone :yesnod:
Mine would sometimes idle too high. I tried the tech tip to reset it but it was still the same. Sometimes ok, sometimes too high. So I took it off this weekend and gently cleaned the tip with some Gum Out.
No more high idle :D
65 is correct, if your idle is fine leave the IAC alone :yesnod:
Mine would sometimes idle too high. I tried the tech tip to reset it but it was still the same. Sometimes ok, sometimes too high. So I took it off this weekend and gently cleaned the tip with some Gum Out.
No more high idle :D
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: [Help] IAC value for 1990 L98 (Flame Red)
I wouldn't touch it either unless there is some symptom of improper operation. Sometimes, it is best not to check these things. I have replaced several parts that ohm values were provided from a service manual (outboard motor for instance) and then when the new part arrives (non-returnable) I found the new one to be the same value as the old, neither of which matched the service manual value.
Burning Brakes
Joined: Aug 2000
Posts: 1,052
Likes: 0
From: Warrenville IL
Re: [Help] IAC value for 1990 L98 (Blazer)
Like the guys said leave it alone if your idle is fine.
One thing I have noticed (on my L98 Camaro) was adjusting the TPS voltage had an
effect on the IAC counts. With my TPS at .63v idle, the IAC counts would be a little higher, like around 58-60 steps but it was a smooth stable idle.
One thing I have noticed (on my L98 Camaro) was adjusting the TPS voltage had an
effect on the IAC counts. With my TPS at .63v idle, the IAC counts would be a little higher, like around 58-60 steps but it was a smooth stable idle.
