I have a 05 Ford F350 Crew Cab 4x4 DRW 6.0
It has been bullet proofed. Changed rear end gears from 450 to 373, trying to help mpg. 12 to 13 hwy.
10.5 to 11 towing around 8,000 lbs. All this with SCT TUNER set on street tune. Had computer flashed said it would help mpg, something about cold start issues. The last shop said I didn’t have a Mass Air Flow Sensor. You could see where the wire harness looked like it had been cut off. It does have an Air Temperature Sensor on it. So they put a 6 wire MAFS sensor on. I did pick up 2 mpg without the tuner, only riding no towing.
All was well until I pulled my first load, still in stock mode, no tuner. The boost pressure starting going up to 30+ on a hill. At steady throttle the boost will go from 30+ to 18 back and forth, you can hear the engine
sound change when it does this. They changed the Exhaust
Back Pressure Sensor; solenoid in turbo didn’t help anything. Finally with the Exhaust Back Pressure Sensor UN plugged the boost went back to normal. They now say the turbo is at fault. I had it replaced less than 6 months ago.
My question is if the turbo is bad, why UN plugging the EBP sensor fixed the boost problem. I spoke with one of the programmers at SCT Tuners; his thoughts were the computer isn’t set up right. Keep in mind the TECHS are ford certified, using ford equipment. I don’t know what to do next. Iam located outside of Winston Salem NC.