a 2003 F250 ccsb FX4 6.0 203,000 miles, i have had it just over a year and it has been a awesome truck... until now.
it starts up perfectly and runs smooth, accelerates fine and has good, or what i believe to be good, power at slower speeds. When i get it up to 50-55 mph it has no more power, as if it has hit a wall. I can keep the pedal at 1/2 throttle and ease it to about 65 but that's about it. if i hit an incline it will slow back down. any more throttle then 1/2 and there is no change in engine sound or rpms or shaking.
another symptom i have noticed it that the accelerator pedal only seems to work up to about 1/2 throttle. Can a gas pedal go bad? haven't been up under there is it an electronic pedal or something?
I am getting no codes on my SCT scanner. I had my FICM repaired by ed @ ficmrepair.com and got the Atlas 40 tune installed. I had low voltage at all cylinders and it was on the way out. I thought that would have corrected this issue. but sadly no.
Oil and fuel filters just changed last week, all motorcraft. I run Diesel Kleen through every tank.
truck has EGR delete, cat delete, SCT tuner, egt/boost/trans temp gauges. new FICM with Atlas 40, 4" lift on 35" tires
I don't have a fuel pressure gauge but i can get one, if anyone thinks i should start looking in that direction. All the other posts I have look through are nothing like what i am experiencing so i am reaching out.
Removed sct performance tune. Return to stock. Same issues with even less power. Its a big turd. Lots of trouble with hills. With the sct it would at least scoot around at lower apeeds better. And now with stock turn it has a longer then usual starting time. Turns over for a few seconds then fires right up.
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