Need a bit of guidance... My 2004 F350 has been having some surging while at steady speeds for awhile. Engine light comes on with no codes and I've had other codes come up without engine light. Don't have the code numbers but one was the glo plug circuit others were different cylinder contributions. etc.
I've replaced the Air flow sensor, the EGR valve and the EGR cooler and Head gasket along with the Head studs have were done a while ago. I also had Ford do a code check to see if the EBP valve worked and he said it did but we didn't go through and key turns or anything.
The other morning truck wouldn't start and I got under the hood pushing the wiring harness into the various sensors and a short while later it started (got distracted and didn't try to turn it over right after messing with the harness).
I just found a mechanic who is well versed in Diesels and has worked on a few 6.0's. He's suggesting getting a new wiring harness for the truck ( big ticket item) and I'm still wondering if it might be the EBP sensor or maybe even the VGT solenoid or that pigtail.
The truck starts well now but I am having a problem that after driving it about 15 - 20 min. it surges and spits and stutters and it will stall on occasion when I stop at a light.
Given all the vast experience here, I need to figure out which direction I should go in. Mechanics typically don't like being told what to do (especially from a woman) but I can't afford to throw expensive parts at this hoping one will stick and this has been so frustrating that I'm about to give up on this truck.

 

Unplug the ICP and see it that helps. It might be in the passenger valve cover, round sensor.

The EBP is mounted on the thermostat housing, remove the sensor and clean it, clean the tube with weed whacker line to open the tube into the exhaust manifold. That will allow it to breath, may help the surging.

Do one thing at a time and test. If it doesn't help. Put it back and then try another clearing the codes as you go. Don't do all of them at once or you'll not know which fixed it.

 

You need diagnostics info. Do the koeo test, looking at baro, ebp, and map. If it's surging, the turbo may not getting a consistent PCM signal.
Also, check your map, hose connection down at the pass side valve cover for splits. A common issue too.
If you can test, make sure those sensors are getting 5v's to operate.
You can wiggle the harness, knowing the injector wiring can lay on some valve cover or head bolts and create havoc.

 

Thank you for the help. To date the code that comes up is P0676 and occasionally the engine light. I did have an issue where the truck wouldn't start after the battery was disconnected to clean a terminal and then reconnected. I got under the hood and wiggled the wiring harness, pushing in all connections. Got back in and truck fired right up. This is the 3rd time I've done this and it works each time. I ordered the glo plug wire harness and it's on the way along with new EGR and VGT wire pigtails so they can be done as well. My mechanic is going only by the codes it's throwing and not really considering other possibilities, which looks like it might take a minute to get this truck healthy. Another snag I've run across is that the build date for my truck is 12/03 and a lot of the 03/04 parts won't work but the 05 parts usually don't include the 04 in their descriptions so I've had more than one interesting discussion with a parts' guy about which parts I need. And just out of curiosity, is it normal when you put your VIN # into the FORD website that it comes back as a SUPER DUTY and not a POWERSTROKE?? Makes it difficult to get the right parts list.
Anyway I will see about cleaning the EBP and the ICP. I do have the bullydog scanner that has gauges for the ICP walve. I'm using the scanner only for engine info, I put the truck back to stock a while ago. What should the gauge be reading if everything is working, also going to check with a voltage meter as well.
Thanks again.