I picked up a mint 2002 4 door dually with an lb7 duramax/allison combo and drove it home to PA from Phoenix 2 weeks ago. Truck has california emissions... yuck.
Ok, so when I picked the truck up I noticed that it has a strange knock only under acceleration. I have been reading about "pilot injection" and was hoping that was what I was hearing... but it kept getting louder and louder... then a bit quieter, then louder... etc etc... then last night on my way home on the interstate the sound went away ALTOGETHER... it was so quiet it sounded like a different truck. I thought maybe there was just some schmegma stuck in an injector and it finally cleared out. By the time I got home it was hammering pretty good again. WTH? The thing sounds like a cummins for crying out loud. The truck smokes a little bit at idle... whitish grey. If you let it idle for say 5 minutes or so and then flog the throttle you get a decent sized whitish-gray puff of smoke all at once. Truck seems to run very good with plenty of power... No SES light... I don't believe there is a tune in it.
I have been running lucas in the fuel for about 2800 miles... I changed the fuel filter as soon as I got home... and the oil doesn't appear to be "growing" in the crankcase.
I took it to my local dealer to have them check the injectors cause they are still under warranty... they said the injectors looked good on the computer but that I had a bad MAF and EGR... (p0404 &p0101) and that was what was causing all the noise. They said the sensors were screwing up the timing and fuel mixtures and causing the abnormal sound. They also said the fuel system was only running at 50% because the fuel filter was dirty... that was after I just put a brand new one in. Could there be something other than the fuel filter that is causeing the flow to be decreased?
I didn't believe anything they said, so I took the truck to my mechanic and he cleaned the MAF and reset the codes. MAF is fine now... EGR is still stuck open. Engine still knocks. I put a blocking plate in the egr and now have a p0401 and a p2141. All egr stuff. When I get the new ecm with the egr deleted those should go away... but the engine still knocks.
ANY IDEAS? Is it possible that all the noise is from the egr being defunct? or is that just dealership BS? I still think I have a bad injector somewhere... but the truck starts fine... and runs with good power. I don't know what to do at this point.
thanks
Duane