its still running BADLY.

[Red '97]

It was in a local shop for quite a while, they replaced the UVCH plugs or whatever they are called, the PCM and it got 2 new injectors. Its now running awefully once again, just like it was before it wouldnt start at all which lead to me taking it in. It shakes and lopes and misses consistently all through the RPM range like a couple cylinders arent firing, and smokes a thick heavy haze just driving down the highway, the color of the smoke is a blueish whiteish. it also got 5.5 miles per gallon hand calculated on a 40 mile trip this evening. what do i have to replace to get it running like it used to??? this think has been an amazing truck but its driving me to drink, it cant be that complicated

[ctd12valve95]

IDM maybe, most of the time the truck won't run when it's bad, but I have seen them cause the truck to run rough

[Red '97]

when it was at the shop i was told the IDM tested out to be good, but i dont know how valid that is. anyone know how i would test mine?

[Diesel_brad]

There is no real test for the IDM with out a good scanner. Any friends around with a 7.3 truck? They take about 2 min to swap them out. Put YOURS in HIS truck and run it. Do NOT put yours in HIS truck. if you have a short you could burn his up

[Red '97]

ok ill have to give that a try. any other suggestions?

[backwoodsboy]

Did the shop replace the pigtails from the UVCH to the injectors/glowplugs as well? If you had a short that caused the UVCH to burn at the connections is possible that the pigtails were affected as well.
Do you have AutoEnginuity or any other kind of diagnostic scanner? Injector buzz test and cylinder contribution test would be helpful to assess if any cylinders are down.

[Red '97]

ill look into both and get back to you. the pigtails did get replaced, but i think i wanna check the wiring job on each to see if everythings where its supposed to be

[backwoodsboy]

Try unplugging the external connectors (the ones you can access with the VC on) one at a time and running the truck. If you have a "dead" cylinder this will at least narrow it down to two possibilities. If the trucks runs rougher/dies the cylinders are firing. If there is little to no difference you have found your culprit.

[Red '97]

sounds like a good plan to me, but now it wont start at all. i walked out this morning to fire it up and it cranked like the batteries were dead, used another truck to jumpstart it and after letting it charge for a while it cranked like normal, dont know what that was about. but anyway, black smoke while cranking and it tries but doesnt fire.i should mention that i just now got it back from a local diesel shop for the same issue, they replaced the UVCH harnesses (all four), put a rebuilt PCM in from ford, and two new injectors. any ideas why it would run aweful yesterday and now not start at all?