High Idle

[ATL 84]

I noticed this morning that my 84 has a high idle. What are the thinks I should be looking at to reduce this idle problem. Any help is appreciated.

 

[Jeb]

Quote Ed McMahon - "How high is it?"

 

[wishuwerehere82]

The crossfire system has two ways it adjusts the idle. The first way is with the idle adjustment screw on the drivers side throttle body. There is a plug the will need to be removed to access the screw. It's on the rear of the throttle body directly opposite the throttle linkage, and is a large Phillips head.
The other way that the crossfire adjusts the idle is with the IAC motors(IDLE AIR CONTROL) on both throttle bodies. They are on the front of the TB's next to the fuel lines. They can be unplugged, and removed with a wrench. They unscrew counterclockwise from the TB's.
Here is an article on adjusting the crossfire system.
http://corvettefever.com/techarticles/4688/

You IAC motor(s) are probably stuck if this is a new problem. You can clean them up and see if it makes a difference, or replace them.

 

[ATL 84]

It is running between 1000 and 1400 rpm and I hear what I think is a vaccum leak but can't find one. All the hoses I can see are attached.

 

[wishuwerehere82]

The main cause of vacuum leaks are at the top gasket on the intake manifold and at the TB gaskets. Try tightening the bolts on the top of the manifold to 25 Ft./Lbs. and also the bolts that hold the TB's on. The Tb's also make a hissing noise is the IAC's are stuck. There's an opening on the left hand side in front of the IAC in the carb throat that you can put your finger over to mask the noise and see if that's where it's coming from. You can also spray WD-40 around the gaskets to find the leaks. It will cause the engine to stumble if you spray it on the leak.

 

[ATL 84]

Thanks wishyouwerehere for the article. I think it will help me a great deal in getting the idle down.

 

[wishuwerehere82]

If the hose that goes to your EGR valve or air pump is popped off orbroken it will make it run faster too. Or if your EGR has broken the diaphram.

 

[ATL 84]

Thak guys The info was very helpful. I found the IAC loose and in deparate need of cleaning and I did a little ajustment to the trottle body. Brought it right down. I think it was idling to high all along.

 

[wishuwerehere82]

Cool!:cool