I have a 1995 Z28 convertible, standard trans, V8 80K and my mechanic thinks one of the cylinders is not working. The engine does not run as well as it should, I am not sure how to diagnose the problem. I was going to have the mechanic change the spark plugs / wires and maybe the optispark to eliminate that as a possible cause.

Thanks,

Chris

 

Chris
Step one: find a better mechanic. Your mechanic either lacks knowledge or equipment. Either way you want to find one that tells you what is wrong with the car. If you tell him what to do and it does not fix it its on you. If he tells you what needs done and that does not fix it then its on him.

 

Yeah find a new mechanic, any decent mechanic should be able to tell pretty quick if it's a bad wire or plug not hitting and a compression test will tell pretty quick if it's a bad cylinder for one reason or another. Some of the plugs are a real PITA to get to on the LT1,even the wires can be difficult.
Back in the day with the old type dizzy we'd just pull off one wire at a time with the engine at idle to figure out which one wasn't hitting then go on from there to figure out why but it's hard to do on these cars.
If I was to throw out a wild guess I'd say check the #8 plug wire, that wire burned twice on my old '93 Z28,it's the hardest one to get to of course.

 

Even past that a pro should have access to a scope, that will tell you spark, fuel or compression. At least it should send them in the correct direction. I had one customer list off about 8 hours worth of work he did to find a miss, I hooked up the scope, found cylinder 6 lean, swapped injector 6 and 4 and saw the lean condition follow the injectors. At the dealer an injector was like $100 so all done he was $160 out the door in about 40 minutes. Course that was in 1990