I have an 87 IROC convertible that has a gremlin that won't leave. The car is a 305 TPI with just barely over 20,000 miles. If I just drive it up and down the street, or to town it runs fine. If I drive it 50 miles or so to a car show, on the way home every time the check engine light comes on and the car all of a sudden has a major loss in power. It obviously is not firing on all cylinders. Another quirky thing to mention is if I drive it out somewhere in town and if sits out in the sunshine for a while the same problem comes up on the drive home. During the rough idle if I shut the car off and turn it back on it will go back to normal. It will run good anywhere from 5 minutes to 15 minutes, and then all of a sudden the check engine light is back on. I've taken it to 3 shops and spent over $1,200 trying to fix this. Even the the local Chevrolet dealership is at a loss. I have done a full tune up, all spark plugs and wires replaced, fuel injectors were cleaned with Motorvac system, cap and rotor replaced, and distributor was replaced. Any help or ideas would be great.

Thanks,
Bozo

 

What codes is it throwing and what has been replaced already?

Check the fuel pressure. One other thing to try, next time it does it pull over and remove the gas cap to see if you have pressure or vacuum building up. IMO, your best bet is to get a factory service manual for your car and diagnose it yourself by following the flow charts.

 

Limp home mode? Bad ECM?

 

Sorry.........don't get car terms. Can you explain ECM.

 

ECM, Electronic Control Module, It's the computer that controls fuel/spark etc.

Limp Home Mode is a common term for when the ECM goes into a default mode that will run the engine, but poorly. (Think MS Windows "Safe Mode") It is triggered by some set of problems that the ECM has sensed. This will (I think) always set a trouble code light and turn ON the cooling fans.

 

My car recently had some nasty ECM issues that took me a couple weeks to figure out. Check the fuse, and fusible link near the battery, should be an orange wire. That powers the ECM and fuel pump. Also, it might be worth pulling the ECM, and cleaning/re-seating all connections. My problem turned out to be a dirty PROM socket (where the "chip" plugs into the ECM). Before doing any of this though, i would pull the trouble codes, it could be something as simple as a bad sensor, or bad connection at one of the sensors.