One for the record books

[2 tone pheonix]

Misfire when all is showing to be GTG( good to go). I'm working on diagnosing a misfire on a 04 snow cone ( avalanche) did compression test, numbers are C1-170, C2-170, C3-160, C4-170, 5-160, 6-170, 7-150, 8-170. Cylinders 5+4 are showing clean number 7 is fouled. Don't have a multi meter so unknown currently whether the wires are within specs( suspect that is the issue at this point,) bad wires don't explain one or the other of the 3 plugs. Injector's are showing flow, as for proper flow, not sure. Also note that there is a weird scraping sound coming from the intake. Coils on those cylinders are good. Did the swap around test, no chasers found. Am getting voltage at coils and injector's. Reception of signal line I will check tomorrow. Its mid night here at the western gate to hell. An ohm test and signal check are the last 2 things I know to check, any other tidbits you can throw my way? And what the heck is the noise in the intake? Not wanting to yank Mani if possible. As for the wires, will be letting customer know he needs a set any how( found 2 old wires under there) p.s. no CEL. MY personal hunch is a set of wires and a big ole bottle of injector cleaner.

[2 tone pheonix]

Misfire, as it came to pass, plug wires were suspect. Let my friend didn't check ohms, course it helps to have a ohm meter on hand when doing diagnostics. The only thing left is the funny noise coming from the intake. No known intake runner so not sure on that issue gonna get shoulder deep for that one, personally to me, sounds like a dry cylinder, but noise is intermittent, and that's what makes it for the books

[Endurante221b]

I suppose one can also:

• Check for codes using an OBDII scanner
• Check the spark plugs to see if they're worn out

Also, I saw this gem on YouTube:

 

The interesting part starts at 7:44 on the video. Weird how the engine starts shuddering after spraying.

Hope it helps. PS: I'm not a technician or mechanic; just trying to offer some resources that might be of use. Good luck! Keep us updated!