Changed from stock delco plugs to NGK TR6 plugs. I now have a missfire on cylinder #6 only on WOT runs. It's very cold here but don't think that should affect things? And it's only on the one plug? Any ideas possible bad plug maybe?

 

how much boost? what did you gap the plug to ?

 

9 PSI sometimes 10 PSI stock gap just put them in as is. Its only the one I get the error

 

Recheck that plug & wire. Very easy to accidentally crack a plug. Or overlook a plug wire with a weak clip(or even missing clip).

 

I actually did pull the clip off that wire. put it back on thought it was the wire. So I installed the factory wire in it's place but still got same result.

 

i would check the gap on that plug. also would maybe try and switch coils with another one and see if it still does it.

 

Just don't understand why it only does it under WOT? Going to pull plug tomorrow and put in factory Delco plug and see what happens.

 

Well swapped in stock plug and still have miss under WOT. Now thinking it may be the coil? Wouldn't I get a miss even when not under WOT if it was a bad coil?

 

Turned out to be a bad intermittent plug wire. Fixed was driving me nuts

 

Glad you got it figured out!