I hope someone can point me in the right direction.

I was taking my 1994 6spd coupe (LT1) out to check to see if I got rid of some interior rattles I had worked on. Everything was running fine for several miles. I got on a stretch of road and decided to put the cruise on. The car held steady at 61mph at about 2000-2100 rpm.

When I went to stop, I pressed on the brake and noticed that the engine was still reving at 2000-2500 rpm. I shut off the cruise, no difference. I pressed in the clutch and stopped the car. After checking under the hood (the throttle cable was not broke and seemed to operate correctly). I restarted only to have it rev up to 2000-2500 rpm.

The entire trip home (~15 miles), the engine would only rev below 2000 rpm if I bogged it down. Clutch in, right back to 2000-2500 rpm.

At home, I checked the codes and only got the standard C12.

Any thoughts as to where to look first?

I did a search on similar problems. Given that it happed all of a sudden (was working fine earlier and the day before), I kind of doubt a vacuum leak (which was one suggestion). Also, it seemed to happen after I put the cruise on and at the approximate engine speed I was at when I set the cruise. Is there a way for the cruise to stick on or is this coincidental?

If it's not one thing, it's another.

Thanks in advance.

Dave

 

With the engine off, grab the throttle body linkage(where the cables attach) and wiggle. If they wiggle more than a little bit, you may have a worn out throttle shaft. This causes the butterflies to bind in the bore.

 

Good suggestion, also you may want to check to see if the TPS hasn't crapped out.

 

When mine stuck I used mobile 1 oil on the butterfly shaft and all surrounding rotational bearings. I relube it like every 3 years, but works every time as long as there is no slop in the mechanism

 

I always go back to when the problem started and it sounds like that was when you engaged the cruise, I think I would disconnect the cruise cable from t-body just to be sure nothings binding, it's easy and nothing to lose.

 

Thanks! I'll take a look at it tomorrow. I had wiggled the throttle cable and it wasn't what I'd call loose. I'll try to disconnect the cruise cable to see if that cure it.

Dave

 

I got it fixed! Rich653 was on the right track.

It turned out that when the cruise control was engaged, the ECU would slide down a little and not allow the cruise control servo to return to normal (and thus always had tension on the cruise throttle cable).

I recently did a brake job and had to move the ECU to get to the cap on the brake master cylinder. I must of not got it back in the right spot.

Thankfully it was simple fix. Thanks for everyone's help.

Dave