Hi everyone,

I am trying to help a friend troubleshoot the stumble/misfire problem he's been having with his car. He bought the car last year and it already had LT1/T56 combo in it. It drove fine until right before he stored it for the winter when it started acting weird all of a sudden.

The car runs but under moderate acceleration you can feel the engine miss and car jerks a little. He also noticed that in 6th gear the car does not accelerate at all, instead it just starts shaking. In 4th/5th it will accelerate but will start shaking if throttle is pushed further down.

So far we replaced all spark plugs. They all looked worn, and some had gap which was a little larger than spec, but there were no build-ups or residues. Wires are next, but I am not looking forward to it and don't want to do it if we don't have to. He cleaned MAF with MAF cleaner spray and to take it out of the equation, we have driven the car with MAF completely disconnected and got exactly the same behavior.

I am looking for help to see if anyone here can suggest what next we can look at.

 

Getting the codes of the computer and a complete tune-up (if it hasn't had one in a while) would be great starting points. The codes should give yo a better starting point for trouble-shooting. I think those distributors still had mechanical advance.... I've had older cars do that cause of it sticking.