Saved from scrap

[Dan2002]

How much of a difference between #7 and others that are showing misfires? You may have narrowed it down to #7 and that would be a big help in figuring out what is going on. First I would suspect the wire. Swap with another and see if the misfire moves too. Then if that doesnt change anything, put it all back original and swap coils and see if that moves the problem to another cylinder. If no change after wire and coil change then you are down to the spark plug, coil wiring harness, output of PCM to fire coils and then the valvetrain and rings of the #7 cylinder. That would need a compression check to see where you are at there and at that time all 8 cylinders would need to be checked to see how #7 looks in comparison.
Ive chased my rear many times over a bad spark plug wire that visibly looks fine but in the dark you can usually see the lightning jump from them to ground depending on where the flaw in the wire is. So at night start it up and with hood raised have a look at #7 to see if you see a light show, also listen closely for a snapping sound. Keep your hands in your pockets so you dont get in the fan or find the lightning the hard way....with your hand. A coil with a cracked housing can do the same and the lightning will jump out to ground (metal) and it will make a snapping sound also. Ignition voltage is over 20kv so dont find out the hard way! Itll make you pee yourself!

update,

after having a few weeks or rain and being very busy at work, today i finally had the day off. i been outside since this morning,

i started by switching, the spark plug, coil and wire cable from a good cylinder to the 7 cylinder, but the misfire condition didnt change,

next i did a compression test, and its good at 150psi.

next i did a cylinder leak down test. and the pressure on cylinder hold, so valves are fine.

now i am thinking on whats next??

i did forget to swap the fuel injector but i dont think thats the issue.

 

[Doubeleive]

update,

after having a few weeks or rain and being very busy at work, today i finally had the day off. i been outside since this morning,

i started by switching, the spark plug, coil and wire cable from a good cylinder to the 7 cylinder, but the misfire condition didnt change,

next i did a compression test, and its good at 150psi.

next i did a cylinder leak down test. and the pressure on cylinder hold, so valves are fine.

now i am thinking on whats next??

i did forget to swap the fuel injector but i dont think thats the issue.

do a backpressure test

 

[Dan2002]

update,

after having a few weeks or rain and being very busy at work, today i finally had the day off. i been outside since this morning,

i started by switching, the spark plug, coil and wire cable from a good cylinder to the 7 cylinder, but the misfire condition didnt change,

next i did a compression test, and its good at 150psi.

next i did a cylinder leak down test. and the pressure on cylinder hold, so valves are fine.

now i am thinking on whats next??

i did forget to swap the fuel injector but i dont think thats the issue.

Here's a video, live data while vehicle in idle