I've got the same engine. Had the CEL as well. After doin a lot of research and searching the engine I first found a vac leak. I fixed it. Light went off for a day then back on. Long story short the 4.2 is know for the upper intake plenum gasket and isolator bolts needing replaced. I did this to mine and while it was tore down found all bout 2 of my EGR ports were clogged shut. Cleaned em out replaced the bolts and gasket and light has been off since. Well until I had to replace both head gaskets. I didn't replace the imrc bushings and now here next month I have to tear it done to replace them. If you do have to replace the isolator bolts and such go ahead save your self the trouble and replace the imrc bushings as well. Just something to look into as why your CEL is on.

 

I saw that same issue on another post, however I'm under the impression that Ford replaced the plenum on the 99 because of this realized problem. I understood this issue was for the 98 and below. What year was your engine?

 

Nope far as I know they didn't correct the problem till the 11th gen. Mine is a 2002 and I had to replace the isolator bolts and gasket. I've seen others with 03 and heritage 04 have to replace them as well.

 

Wow, I'm glad you've said something as I still have mine in pieces. Just to be sure, Are we talking about the gasket between the upper and lower manifold? Also, the isolator bolts are the bolts on top? The ones holding the top plenum to the bottom manifold? Is that right?

 

Correct. I'll be tearing my apart again this weekend to replace the imrc bushing. One or two broke and I've got the CEL for that.

The isolator bolts should run bout 25 bucks. I got my from summit racing (I live bout 20 min form them) plus got the gasket and bushing there as well altogether cost be bout 55 bucks. While its apart check for vac leaks. I found one in an elbow. I wouldn't have seen it if I didn't take it off. I can't recall what it's for again though. If I think if it I'll post it.

 

I hope I'm not in over my head. If you have any more info or pics, lemme kno. Thanks

 

It's not that bad. If ya got it tore down now that's the hard part. The hardest PITA thing I found was getting the back 3 bolts off no room to move your hands. I've got a post on this somewhere. I'll find it and post in it so it brings it back to the top of this forum.

 

Just follow the link in the post above this. It helped me out a lot.

 

It's the how to fix article.

 

Hmm. I can't see an article. Possibly as I'm using an app. Do you have the link?