Just changed the head gaskets on a 97 F-150 4.6 because of a problem with exhaust getting in the coolant. The truck ran fine before the head gasket change. Now after I put the new head gaskets in the trucks runs very rough. It is throwing no codes, and it seems to have good power, but runs rough the truck even shakes at an idle. It has all new plugs and I checked all of the wires. I checked the compression on all cylinders and it has good compression. I cannot find any vacuum leaks. I don't know what else could have happened when I changed the head gaskets. I thought about timing chain being off a tooth or something, but I would lose compression wouldn't I? Where else should I be looking?

 

one tooth on the cam might do it... i doubt it would loose compression with that. there is some overlap on the valves so it would still build up compression... as i was reading the story, cam timing was my first guess.. since you just did the head, it is probalby related to tthat work?????

 

This is likely the problem.
JL

 

I am going to have agree here . Most likely something with the repair. Maybe bad or cracked plug, bad plug wire , vacuum line loose or in the wrong place.

 

I just ran into this after chasing a problem for months I finally found the solution. Then this miss showed up. First time we had ever seen it. Well it turned out after the other problem was over we noticed the miss. It was the fuel injector.