I ran into that problem on my old escort zx2. Chasing misfires. replaced the plugs (autolites) about 5000 miles prior. Didn't expect it to be the plugs, changes wiires, coil, pcm, compression check, timing belt and rechecked the timing (again). replaced the plugs with NGK never had another misfire problem. Threw those autolites as far as I could a swore like hell.

 

Same here, Autolites done me like that, -on two cylinders.

Sucked!

 

I'm curious to know if anyone has found a fix for this problem. I am experiencing the same issues with my truck. It's really frustrating.

 

No fix yet. I replaced all the coils with those cheap coils off of e-bay. Had the misfire come back one time. Removed the coil on the affected cylinder, replaced the spark plug and swapped the coil with a different cylinder..

Test drove the vehicle again for 3 days. 50+ miles later no problems. Took the vehicle out on the interstate. Went WOT @ 85 MPH got a flashing MIL and hard misfire. Found misfire on cylinder #4. By the time I got home I also had a dead mis at idle on cylinder #8. Removed spark plug and found spark plug screwed up.

By looking at the spark plugs I would think it was running lean. But the fuel trims are all normal?

here's a picture of the spark plug.
Also the spark plugs I pulled out of 3 and 4 where slightly white.


(Repairing the threads is another problem. I'm making another thread for that.)

 

Wrong plugs for the engine.

 

I'm looking into repairing #8 cylinder which is the one with the helicoil. I have a motorcraft ready to go back into the engine. Cylinder #4 already has a motorcraft in it and still has the misfire. I'll get this cylinder repaired, run a fuel pressure test and go from there.

 

Looks like a Bosch that's been used in a Triton. Quite common.