iac problem
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Intermediate
Joined: Sep 2002
Posts: 34
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From: Columbus OH
iac problem
1984 cross fire , when the vette is started cold it runs rich and the rpm is low ..about 800 rpm, When the engines warms up it runs at 600 to 700 and seems OK for mixture. When I turn the A/C on the engine loads down when it should compensate with a slight increase in rpm.My question is could the iac be stuck on both throttle bodies? and at cold start up shouldn't the rpm be more then the 600 to 700 rpm. any info on this cross fire setup and the IAC in perticular would be of big help. 
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Don't hear of too many cross fire questions anymore...I think there is a dedicated forum out there too-might get better info...
Generally, IAC's are reliable...only they tend to get dirty with carbon/gummy deposits. Usually, one can take some brake cleaner or carb cleaner and clean the areas (with engine off) and solve the simple issues.
Good Luck!
Generally, IAC's are reliable...only they tend to get dirty with carbon/gummy deposits. Usually, one can take some brake cleaner or carb cleaner and clean the areas (with engine off) and solve the simple issues.
Good Luck!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The odds of two IACs failing at the same time are absolutely phenomenal. However if they were both cleaned at the same time, last time, it is reasonable to expect them to both need cleaning at the same time, again, next time (now?). The ECM performs the function of the choke by enriching the mixture and providing a faster idle, by opening up the IACs, when the engine is cold. It seems the rich mixture is there, verifying the engine coolant temperature sensor working. My guess is that the IAC valves and passages need cleaning, or that there is a wiring problem between the ECM and the IACs. It wouldn't hurt to check the output of the engine coolant temp sensor, also.
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by No Go
Don't hear of too many cross fire questions anymore...I think there is a dedicated forum out there too-might get better info...
Good Luck!
Good Luck!
RACE ON!!!
Drifting
Joined: Mar 2005
Posts: 1,923
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From: GA
I don't think that both IAC's would have to fail to get what you are seeing. The CFI has 2 of each, so they have to be "balanced", so if one were to fail the system wouldn't be balanced any more and you would see lower RPM's like you report.
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Ah...ok.
My comment is not many cross fire questions on this forum that I've seen in a long time. I would trust folks that have similar cars to provide me the best leads on 'issues.' I understand it is basically a twin TBI on a cross ram manifold...don't mean I know what is wrong with his car though...
Race On...
My comment is not many cross fire questions on this forum that I've seen in a long time. I would trust folks that have similar cars to provide me the best leads on 'issues.' I understand it is basically a twin TBI on a cross ram manifold...don't mean I know what is wrong with his car though...
Race On...
Originally Posted by CFI-EFI
The biggest difference in Crossfire IACs and TBI IACs, is their quanity.
RACE ON!!!
RACE ON!!!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Morley
I don't think that both IAC's would have to fail to get what you are seeing. The CFI has 2 of each, so they have to be "balanced", so if one were to fail the system wouldn't be balanced any more and you would see lower RPM's like you report.
Originally Posted by No Go
I would trust folks that have similar cars to provide me the best leads on 'issues.' I understand it is basically a twin TBI on a cross ram manifold...don't mean I know what is wrong with his car though...
RACE ON!!!
