1990 c4 high idle
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1st Gear
Joined: Nov 2013
Posts: 1
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1990 c4 high idle
my idle is at 2000 to 3000 rpms. I have replaced iac and changed fuel filter When I remove the pcv valve and put my finger over the hose going to it the rpms lower the more I do this the lower it goes. Then will stay idle at where ever I stop it and put pcv back in. Then when I restart car it is at 3000 rpms again. Also very poor power.
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
You have a massive vacuum leak somewhere.
The other half of the PCV system is on the passenger side valve cover. A hose (and maybe a pipe -- it changed over the years) connects the valve cover to the throttle body. Check there.
The only other thing I can think of offhand that would cause that kind of leak is the brake booster. Remove the rubber hose from the check valve on the booster and plug the hose with your thumb to check.
The other half of the PCV system is on the passenger side valve cover. A hose (and maybe a pipe -- it changed over the years) connects the valve cover to the throttle body. Check there.
The only other thing I can think of offhand that would cause that kind of leak is the brake booster. Remove the rubber hose from the check valve on the booster and plug the hose with your thumb to check.
