I have a '91 Chev Corsica (3.0 L). It recently had some overheating problems - which my mechanic has diagnosed as a broken sensor. However, when I started the car to bring it to the garage, it started running very rough - as if it only was running on three of the six cylinders. Although it overheated, it was still running fine when it was last shut off about two weeks ago. The mechanic is a small town mechanic with a limited number of diagnostic tools. He frankly admits that he doesn't know where to start. There is spark to all six spark plugs and the compression is fine on all six according to the mechanic. Before he starts taking the engine apart, piece by piece - is there anyone who has experienced a similar problem.

Thanks

Bernie

If youre gettin spark at all six and compression on all six is good, you need to look towards the feul system. Probably not gettin feul in a few of the cylinders, so check the injectors.

Well, I had a 1990 Corsica that overheated on me. The first problem was the catalytic converter - sounded like marbles loose under the car - and that caused the first overheating and led to internal head problems. The rough running could also be motor mounts.

i have a 91 corsica and experienced what sounds like the same situation. it turned out that my EGR valve had died and need to be replaced. it costs a couple hundred to buy the part new if thats what it is, but if you find out that it does need to be replaced i would check ebay, i bought mine for like 20 bucks there