So the 03 4.7 with 118k has developed a random idle misfire on cyl 7. It's somewhat consistent, but not constant. I've replaced the coil, plugs, injectors, added a Superchips 3865 tune to it, runs great otherwise but still has the random idle misfire that can be felt. Doesn't have any type of hesitation, doesn't seem to miss at all under load. No unusual ticking, nothing more than it's ever had anyways. I have not done any leakdown or compression test, but can tell you that it absolutely does not crank over with a lope like a low compression cylinder typically does, the randomness of the misfire kinda leads me away from that being an issue too. Anyone have any ideas for me?

PFA

 

Marginal electrical connection for the coil or injector??

 

Certainly possible, though they looked great. I'll ohm them out, see what I get.

 

Be sure to check them at the PCM side as well.

 

Solid suggestion, I haven't touched those plugs in years, could absolutely be a source of trouble.

 

I would do a compression test first to rule out mechanical causes.