This is my first posting and I would like to thank all of you for your vast insight into my 6.OL diesel. I just found this sight the other day and am simply amazed at all of the useful information that you have posted. I started my research because I have a 2003 F350 with a 6.0L that has approx. 75000 miles on it and am having trouble with it surging/bucking when I run it at a constant speed over 60mph. Just a little background on the truck I do have a 4" MBRP exhaust on it with a cat delete pipe, Edge Performance chip and a K&N filter charger system on it. The chip & other mods have been on the truck since day 1 and I originally thought it could be the chip so I removed it and the truck had the same issues. Also, I did have the turbo and EGR replaced at approx. 35000. I read the forum on the EGR bypass/delete and performed the procedure last night but still the same issue came back. When the truck starts to act up you can hear a low thumping noise coming out of the air cleaner as it is an exposed air filter (K&N's design). It sounds like the VGT is acting up for one reason or another. Thinking this might be the issue I tried to unplug it while the truck was running to see if the problem cleared up. Upon doing this the black plastic housing holding the 2 wires going into the VGT broke and I did not see which wire went on which terminal so I just guessed and plugged the black w/blue stripe on the left terminal and all blue wire on the right terminal and it seemed to fix the problem. Was this dumb luck? I never had this plug off before so am I masking the true issue? Upon returning home I verified with a friends truck to see if I put the wires on right and I did not so I changed them around and the truck started running rough again. My questions are does it matter which wire goes on which terminal and does anyone have any other ideas what could be wrong? Please let me know. Thanks

 

I just bought a 2003 F350 with a 6.0L that has approx. 75000 miles on it and am having trouble with it surging/bucking when I run it at a constant speed over 60mph. What's going on... cknapp posted same problem 9/16/08 but I don't see any answers.