My 1997 F-150 4.6l runs slightly rich at idle. I Smell unbunt fuel at the tailpipe. Ive been having a intermittent missfire lately. Wondering if this can be a culprit? Ive changed everything but the wires and those will be soon. Just something that crossed my mind.

 

Could be if you have a cylinder that's not firing it's just gonna dump fuel

 

Replace the Vapor Canister.

 

Well I knew that. My scanner **** out a few weeks ago. I know a flashing CEL is missfire. But there is a constant CEL also. I was wondering if a bank too rich can cause a missfire because its not a Constant missfire.

 

Hmmm... didnt know a vapor canister can cause it to run too rich. My 92 had it bypassed since it got cracked. And didnt run rich..

 

Also it only seems to do it once its warmed up.

 

My 00 only would miss after being warmed up and it was just the coils

 

I just replaced them..... fuq....

 

leaky / stuck open injector can do it too

 

Yay. Hoping its not. $200x8 is not good odds...