I picked this truck up a few weeks ago; got it for a sweet deal, but the engine has a misfire in it. Guy said he recently swapped out the plugs, and put Champion copper plugs in it. I seem to remember that these engines needed platinums, and thought that this may be what was causing the problem.

Well since then I tried a different set of plugs out of another 4.3 that was running fine, and also tried swapping out the wires as well. The miss is still there! Really noticeable around 2,000 rpm's, but it's there throughout the rpm range.

Funny thing is that while you're driving, the check engine light will flash on & off, and then stay off for awhile, and then start flashing again. But when we hooked up a scantool to the truck, no codes were present!!!

Anyone have any idea what may be causing this; or how to figure out how to read whatever's flashing the CEL? I don't want to just start randomly swapping out stuff; I'd like to try & pinpoint the problem. Any help would be greatly appreciated!

Thanks!

 

just a thought you might try running some sea foam through it. almost sound like a poppet might be sticking on one of the spider legs. you can put it on a good scan tool and set it to record, take it for a drive, and then look at the results of what it records. this works nice when you have a problem that doesn't happen long enough at a time to throw a code.

 

hmmm.. interesting theory. I happen to have another spider injector in the garage; maybe I should try to swap it out. couldn't hurt!