Just bought an 08 6.4L with ~140K on it. The previous owner was having issues with the truck not running over 60 mph on the highway. Did some research and bought the truck thinking a DPF delete would fix the problem, Did the DPF delete w/ minimax and the truck ran great for until I took it out on its first trip out of ~300 miles round trip. on the way back the truck started to overheat and as I as suspected it ended up being the front cover. Put it back together and now it runs real rough at idle through 1000RPMs. It also vibrates now at highway speeds but not nearly as bad. Runs real smooth just after going into the last gear ~50mph. According to the minimax there are no codesAnyone have any ideas?

I have used this website for my 01 7.3 extensively and have always been able to find someone else with the same problem by searching. This would be my first post as I am not sure how to diagnose this problem.

Anyone know if AE would diagnose a bad injector on these trucks? really like to work on my truck myself so anyhelp would be appreciated

 

Anyone know if installing the harmonic balancer off 90 degrees from its original position would cause this vibration?

 

probably so. Put it on correctly and try.

 

I know this is an older thread, but did this ever get solved? I have one similar. Other things are pointing to the HPFP starting to fail.