I have been chasing an intermittent misfire for a while now. It started a few months ago. It would misfire slightly but no codes, then finally it set P0301 so I pulled the COP and boot, cleaned them gooped the boot up with dielectric grease (nothing crazy) and re installed. It didn't seem to help but the code didn't come back for a while. When the code came back it was still P0301. This time I switched #1 (front passengers side) with #6. The miss still happens intermittently but it hasn't set a code yet. does anyone know how many misfires it takes to set a code? The SES light NEVER came on, but as I understand it, thats normal.

I ordered a Scangauge II that should be here tomorrow so I don't have to keep going down to the parts store to have it read.

Thoughts? It seems to be worse in humid or wet weather so i am pretty sure its a COP or a boot. But I want to be sure before the military fix of just throwing parts at it.


Eric

 

Wait for it to come back, if it moves with the COP, replace the COP.

I'm not sure if there is any real documentation anywhere on how many misfires it takes for the OBD-I system to throw a (pending) code. When I last looked at the Ford docs, it said "increased threshold" over OBD-II, but not how MUCH they increased it.

https://www.ford-trucks.com/forums/5...t-come-on.html

 

The only issue with waiting, In two weeks I am using the truck to pull the boat over the West Virgina Turnpike and I will be out of town on Buisness next week. Ohhh well. Maybe my scanguage will help diagnose.