Questions and Answers

Racing Chevy S-10 Blazer Q. I have a 1989 Chevy S-10 Blazer with a 4.3 liter V-6 and automatic transmission. Problem: Idles to fast. I messed with the linkage cleaned the EGR cleaned the ICS but to no avail. I noticed the vacuum line going from the EGR to an electric switch of sorts that had another vacuum going to a vacuum port on the throttle body.

I disconnected the hose from the electric switch and connected it directly to the EGR and this brought the idle down immediately. Unfortunately it also made the engine lope I reconnected the hoses back and looked closer at the switch in question,

It had a small sponge filter on it? And while I ran the motor the front of the switch was sucking vacuum to atmosphere!! Am I on the right track here? What the hell is that switch for? Hate to put an idle control if this is the culprit. What do you think?

Thanks for any response!!

A. While this car is running listen VERY carefully under the hood. Do you here a sucking sound? These engines were prone to "sucking" the throttle body base plate gaskets in. This gasket is under the throttle body.

While it's running spray some carburetor cleaner around the base of the throttle body to see if it changes speed. You will need to remove the throttle body to change it. This leak allows more air into the engine that the IAC valve didn't know about, thus explaining the high idle.

Put the EGR hoses back. They wouldn't cause this problem.

Additional Information provided courtesy of ALLDATA