Recently got CEL. Scanner said p306. Cleared the code and bought new plugs. They all look fairly normal other than one, exhaust number 7 and was completely covered with crud. Runs okay but after going freeway speeds for several miles it will hesitate on take off from a stop. Time for new coil packs? TIA

 

What plugs did you use?

 

I used NGK iridium plugs. I should have mentioned that it was doing the hesitating thing before I changed the plugs. I was hoping the new plugs would take care of the problem.

 

These trucks prefer plain ol copper core plugs. Anything else, you are asking for trouble.

 

If you suspect a bad injector, swap it with another cylinder and see if the issue travels along with it.

 

The plugs I removed were the originals. They were iridium too. The truck only has 50k on it. It belonged to the Colorado Game and Parks. I think it spent it's whole life on dirt roads and never went over 45mph.

 

#6 misfire but plug 7 was covered? wondering since its never been beat if a valve is sticking, might want to do a seaform flush, put some high octane gas in it and run it up and down the highway also get a set of autolite 3922 plugs, these are a step cooler then stock, get rid of those iridiums .also those cats could possibly been clooged

 

Im sure the maintanence yard changed those plugs because copper is what they came with and what factory recommends for replacement!

 

All my research shows that the factory exhaust plugs were a Bosch Iridium plug. I'm thinking maybe I have a dirty injector.

This what my plug looked like!

 

What year is the truck? The original 4.7 manual has a big bold lettering saying to stick to copper plugs.

Not sure about the HO's, But we have seen this before on this forum,...