I drive my truck twice a day for 2 hours each way at roughly 70mph. After about 30 minutes the truck makes a clunking noise and the turbo drops down. This has happened when I am running the truck bare or with a 10000lbs trailer roughly 30 minutes into the ride for the past 3 days. The turbo will not go above half and as I press the gas the truck will not increase speed. If I drop the truck in to neutral and shut down and restart the engine during driving the problem goes away for 5-10minutes then returns. Does any one know what could cause this? Water in my fuel filter was mentioned by one guy. I also want to mention the DPF has not gone into a cleaning cycle for many months. Could this have anything to do with it.

 

Is it not going in to regen or are you just not noticing. If you have the latest flash on your computer the "cleaning exhaust filter" message is only on for a few seconds and that's the only sign you get. If you were in for service they may have reflashed it and not told you. Otherwise, is the tailpipe black? The soot has to be going somewhere, if the trucks not regenning which seems unlikely, then it is either going through and the tailpipe is black or the DPF should be clogged up and may be your problem. Or, more correctly a symptom of the problem. Could be a sensor failing to tell the computer that the DPF is full, causing the computer not to send a regen, not a big deal. Either way if you are under a 100 thousand miles I think it should be repaired under warranty. As to water in the fuel, just crawl under the drivers side and look up on the frame, that is the first water filter. It has a yellow handle and a spout. Put a glass or jar under the spout and open the yellow handle and run the glass half full.. If there is water in the fuel you will be able to see it, it won't mix. Good luck. If that don't help just wait a little while and some of the smart guys on here will give you more ideas.

 

Good chance it is the high pressure fuel pump. I had a similar problem with mine a couple weeks ago - no check engine light, etc. Took it in and they ran the tests. Cab off repair - new HPFP and associated parts. Took about three days and I could not even tell they took the cab off. Dealer did a great job.