I've been helping a guy in my club track down a misfire. I hooked it up to a tech-2 scanner at work and I determined it is #6 that is missing. I put a new wire on it, car ran good for a couple of days, then started missing again. Today I hooked it up to the scanner again and it is #6 again. I pulled the wire off again, but this one still looks brand new, no sign of burning or tunneling, nothing. Well I throw a new wire on it anyway, and it misses worse than before. We decide to throw all new plug wires, and plugs at it in the next couple of weeks and off he goes. Well, her just called to inform me that about 1/2 way to his house it started missing extremely bad all throw the rpm range and under all conditions. I have no idea what is going on. The only thing I have done is replace the #6 wire twice. Any ideas?

 

Opti? Coil? Coil wire?

 

Every bad opti I've ever delt with will generally throw misfires on all cylinders on the tech 2 when using the misfire graphic, he is only throwing them #6. I have a look at the coil and, coil wire next time I get it. Anything else?

 

How did the plug on that cylinder look?

 

Maybe try checking the injector for that cylinder?

 

The porcelin part looked good, I didn't pull the plug all the way to check the other side. He just had new plugs put in it not too long ago, but did drive with the miss for quite a while before I changed the wire the first time.

 

It might be a good idea to run a compression and or leak down test on that cylinder and compare it to a few other cylinders.