I have a 00 F250, 7.3. And its going to drive me to drink. Eerrr ok, well i drink anyway but i swear its possessed.
Around a month ago it started to get a rough idle. Ran codes got a back pressure code, replaced pipe and sending unit.. No prob , code gone but idle still rough and getting rougher.
Ran a cyl contribution test. got cyl 4 and 5. Ran inj buzz test all passed.
Changed 4 and 5 no change, then two days later idle got smoother not gone but much better. Codes for 4 and 5 still there.
a few days later rough again no codes just 4 and 5 on cyl con test.
Changed harness, and gasket. 4 went away 5 stayed and now 8 joined.
then got smooth again......
A few days later rough is back, real rough sounds like its running on 4 cyl.
ran every test i know , got 5 and 8 in cyl contribution again. Changed 8 inj and harness ... no change what so ever.
I am about to shoot me, the truck and maybe the dog " if i had one"...
Now i am a Heavy Diesel tech and can figure out most stuff with out even looking at it but i am getting killed on my own damn truck.
Scans are being done with an OTC genysis.
I need a pair of eyes from the out side looking in..