1989 idles up and down
Thread Starter
Heel & Toe
Joined: Jun 2005
Posts: 19
Likes: 0
1989 idles up and down
when i first start the car it runs normal but after it runs for a few minutes the rpms go from 500-700 up and down.i replaced the iac because it kept stalling and that fixed it from stalling.so what could be causing this to happen?
Instructor
Joined: Jul 2006
Posts: 102
Likes: 0
From: Cary North Carolina
I am pretty new to the forums and had my vette a little over a month, so senior members/owners, correct me if I am wrong...
culuknn2,
To find the leak, get a can of carb cleaner with the thin hose that attaches to the nozzle. Then while the car is running, spray the end of each vacuum hose one at a time. If you hear the engine rev higher after a spray, that's where the leak is. Don't stop though, keep checking, you may have more than one leak.
culuknn2,
To find the leak, get a can of carb cleaner with the thin hose that attaches to the nozzle. Then while the car is running, spray the end of each vacuum hose one at a time. If you hear the engine rev higher after a spray, that's where the leak is. Don't stop though, keep checking, you may have more than one leak.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Pretty close shilly, thing is you have to check the entire length of the vac. lines, not just the ends, our plastic vac. lines are formed, and personally I found a line cracked in one of its curves. 
And it's a good idea to check for vac. leaks on the intake as well.
And it's a good idea to check for vac. leaks on the intake as well.
Drifting
Joined: May 2004
Posts: 1,747
Likes: 1
From: Port McNicoll Ontario
Originally Posted by rick lambert
And it's a good idea to check for vac. leaks on the intake as well.
My problem was similar. Leak was at the drivers side runner by the cold start. WD40 works too or a not lit propane torch.
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