SgtMajM

I need help. My 1984 Corvette will idle fast at times. When this happens I can let off the gas the pedal and it car will continue to go the same speed. Until I step on the brake the idle will not come down. On other occasions the idle will come down and it will run rough when I am stopped at a light. In addition, the cruise will not work. I have checked and replaced every vacuum line I could find that looked/tested bad. I changed the cruise control servo, switch, and cruise control lever. I have also changed the plugs, cap, rotor. It looks like the previous owner replaced most of the control sensors. I am out of ideas. I appreciate any help I can get.

AirForceOne!

You might check out the throttle positioning sensor?

http://www.ecklerscorvette.com/corve...1982-1984.html

PeoriaMonkey

I'm wondering if the OP found out why his car idles high at times. My husband and I just experienced this for the first time today while out for a drive. Everything started out normally but a half hour into it the car started idling at about 1700 rpms. My husband noticed he didn't have to press on the gas to maintain speed and at the traffic lights it was pretty obvious something was wrong. He pulled into a shopping center and looked under the hood and the only thing he noticed was the cable for the cruise control wasn't as tight as it should have been at module it connects to. He tightened it by hand and started it back up but the high idle remained. Not knowing what was wrong we headed back home and when we were about 10 minutes from home the car started acting normal again.

I did a search and it looks like vacuum leaks are what most say to look for, but it might be hard to find if the problem comes and goes like it did today. Wish me luck.

Diane in Peoria, Arizona

hemivett

Go wiggle your throttle shafts. I'm bettin one or both are bad. h

PeoriaMonkey

Nope both are fine. We went outside today and tried to wiggle and they were both tight.

Took the car for another drive and it worked fine today.

Diane from Peoria, AZ

vetset84

try spraying some starting fluid around the intake base. a couple of quick burst and see if the engine revs, could be an intake gasket or some small other leak. Do your brakes work good? thers that check valve for the booster that could be acting up.

PeoriaMonkey

That could be it. We noticed that the brakes can be spongy at times. Thanks, we'll check that check valve out. LOL

Diane in Peoria, AZ

vetset84

I don't think that spongy brakes is a symptom of a vacuum leak, i was thinking more in the lines of a split in the line, leaking valve or the booster itself. you would know if the booster wasn't working, like having to apply a lot or pressure. just trying to rule out a vacuum leak. If not then its looking like a TPS or IAC problem.

PeoriaMonkey

It looks like the rubber grommet on the check valve is allowing a vacuum leak once the car is warmed up. We found someplace online that has them for $15.00 a piece. For that price is seems a good place to start. If that doesn't solve the problem then maybe a new valve for $150.00 on ebay. lol. If those aren't the cause a new brake booster might be in order.

Diane in Peoria, AZ