[halfhere]

So a few weeks ago I hadn't started my truck for a while and decided I needed to let it run. I went about mowing the lawn and when I came back to the truck it was running like crap. Missing and no power at all. A visual inspection revealed the uvc harness for cylinders 2 and 4 was burnt. All of the other 3 looked good. Drained fuel filter canister and replaced the valve cover gasket and the one uvc harness on the drivers side. Started truck and same thing; really running lousy. Took truck to local mechanic. He checked the OBD and said #1 cylinder was low output and #5 was no output. Buzz tested injectors and all tested ok. Since he was doing this for free he stopped there and said it would take more extensive testing to determine what the problem was.

At this point I still had one new uvc harness so I put it on the #5 and #7 cylinders hoping for a miracle. Put the truck all back together, fired it up, and wallah. It ran really bad for about three seconds then straightened out, check engine light went out and since then I've ran it about an hour or so and it's still running like a top.

Does anyone have any ideas what might have caused this malfunction? I'd like to avoid having it happen again if possible. Thanks for all the previous help

halfhere

 

[Patrick Feeley]

was your mechanic running the contribution test (and was it at normal operating temp when he did it)? Anyway, many times the contribution test will give different results for as many times you want to run it. Cylinder 1 could be low output, but still functioning. You probably fixed cylinder 5 with the UVCH (although the VC gasket still copuld be iffy). Generally the burned harnesses will be shorting the injector wires and glowplug wires, in which case the IDM will shutdown that particular bank of cylinders. Cheers!

 

[William from Louisiana]

Many times, it takes a good drive around the block to get the computer to adjust to the new settings. (new uvc harness, etc) and thus would run much better.

 

[halfhere]

Yes it was a contribution test. Sorry for the lack of intelligence here I've never had to have anything diagnosed on my truck before. I didn't check the temp gauge on the truck but it should have been very close to operating temp. I was going to unplug the idm and pcm and check electrical connections for corrosion etc. but I think at this point I'll just drive it and see how it acts unless there is better advise.