Yesterday my 97 Cobra developed a misfire at all engine speeds in any gear. I don't know if it's spark plug, injector of something else. It just sounds like it's running on 7 or maybe 6 cylinders. There is no error code or MIL indication (check engine), so I'm wondering if anyone might have a guess at the most likely cause. The car has 67,000 miles on it and everything under the hood is original except CAI.

 

Is it at idle too? plug wire maybe. In a garage with the lights out pop the hood and start the car. Once you hear/feel the misfire, check for blue sparks along the wires and the boots to see if you can see anything. You might need to rev the engine a bit to get bigger sparks if they exist.

If you don't see anything, shut the car off, let it cool down, then inspect each plug boot and wire for white marks on the wire. White marks on the wire are signs of where the spark has jumped and found it's way to the nearest ground.

 

if you could get access to a scan tool with power balance/misfire monitoring you could see what cylinder is the problem

 

Thanks for the advice....plugs looked like they were orginal and the car has 67,000 miles on it. New plugs didn't fix the problem, but a new set of wires did.