Not Running!

[ZR-1Mike]

I'm needing a little help. I've not been driving my '91 much in the last year and a half and last October on a trip we stopped for lunch and when we came out the engine started fine but idled and maintained cruise power poorly. I replaced the coils over the winter and now under WOT it runs like a beast but still has major problems with smoothness at idle and cruise. There is a tech in town trained 20 years ago and he found a bad vacuum line but won't take it any further. I live in SE Oklahoma and am looking for someone competent on LT5's. Anyone out there have any ideas about a fix or someone that might be able to help it? Now that she's not running I really miss her!!

[Kevin]

I wonder how far jerry is from you. he's in edmond i think

[1990 quasar blue]

I'm needing a little help. I've not been driving my '91 much in the last year and a half and last October on a trip we stopped for lunch and when we came out the engine started fine but idled and maintained cruise power poorly.

Any chance you popped the hose off the map sensor?

[ZR-1Mike]

The first thing I checked was the map sensor, but wasn't that lucky for it to be that simple! I've met Jerry a couple of times, do you think he knows someone near by to look at it? I'll leave him a message... Thanks

[1990 quasar blue]

Stock injectors still? Any check engine light?

[VetteMed]

If you were able to change coils yourself, then you already can do everything necessary to rule out vacuum leaks under the plenum. A mityvac or similar tool can be used to pull a vacuum on the various lines and fittings under the plenum, unless of course there's something obviously disconnected when you get in there.

If the cruise and/or HVAC aren't working 100% properly, then that would increase the likelihood of a vacuum leak being present.

I recently found a vacuum leak where the brake booster hose meets the plenum. It seemed snug, but after I put a hose clamp on it to snug it up, the idle smoothed out considerably.

Also, a failing throttle position sensor could do funny things at part throttle (not usually at idle, though).