Cutting out under steady pedal?

yotaneck13 · Sep 17, 2013

Ok i had this problem a while ago. I was on my way to meet a fellow psa member. He was meeting me to trade his injectors and turbo for my dirtbike.

Anyways cruising down the interstate truck starts surging. Like something was binding up. My buddy and i thought the rear diff was locking up. So i limped it back home. I pulled my rear axels and driveshaft. This seemed to fix the problem.

Drove on my front axel about a week and it started doing the same thing again. This time it was doing it under light pedal on back roads. I yanked my transfercase and rebuilt it. New chain and berings and seals. I reinstalled the rear axels and drive shaft. Problem went away again.

Fast foward two weeks to last saturday. Problem is back. Again just driving normal back roads. Im holding my foot steady and it sounds/feels like im feathering the throttle. I hooked the modis up. Multiple codes from way back.
I did get a map sensor code and a glow plug indicator code. Wts light does not come on and hasnt for a while. (No blown fuse that im aware of. Ive checked them several times. Both under hood and above e brake.)

Injectors all passed the buzz test. Glowplugs passed their test. Cylinder 8 failed contribution test. Im stumped. Could a bad map sensor cause this? I replaced gauge cluster and throttle sensot on pedal last fall when i lost my pedal completly.

Under wot it does not surge and my boot gauge settles at just above 20 through out all gears. Truck is currently not running anykind of tuner. I just have an intake and straight pipe exhaust. Any help would be appreciated...and or bashing if ive missed something simple.

NOTE: truck is a 2000 f350 cclb drw. 4x4 auto. Just over 215k

sent while hittin' easy street on mud tires

Big Calo · Sep 17, 2013

Throttle Position Sensor? Got another truck you can swap out to test?

yotaneck13 · Sep 18, 2013

No i dont. Are you talking the one on the pedal assembly its self? I replaced that last fall. Mabye ill bolt the old one back on and see if it changes. It wouldnt act up while i had the modis hooked up running data stream. So i dont know if im loosing signal to the pedal or not.

sent while hittin' easy street on mud tires

PWRstroke_smoke · Sep 18, 2013

Friend had these symptoms and it was the wire harness that connects above the driver side valve cover. It was rubbing and causing a short on the valve cover, it didnt fall down and rub until it was warm under the hood worse on rough roads.

Big Calo · Sep 18, 2013

yotaneck13 said:
No i dont. Are you talking the one on the pedal assembly its self? I replaced that last fall. Mabye ill bolt the old one back on and see if it changes. It wouldnt act up while i had the modis hooked up running data stream. So i dont know if im loosing signal to the pedal or not.

sent while hittin' easy street on mud tires

Yes, electric is the worse. At least you have some sort of scanner to help you along.

yotaneck13 · Sep 18, 2013

Quick glance at the harness and it doesnt look like its rubbed raw. What connector are you talking about. The one for the injector harness.

sent while hittin' easy street on mud tires

yotaneck13 · Sep 18, 2013

Found that connector. One pale color wire is worn into but not clear through casing. Other than that it looks good. I was really hoping that was my problem. I really think its electrical at this point though.

sent while hittin' easy street on mud tires

PWRstroke_smoke · Sep 19, 2013

nice hopefully that was your issue post back when you find out

yotaneck13 · Sep 19, 2013

No i said that wasnt my issue. The wire wasnt worn clear through. I wrapped it in electrical tape and then the whole harness right there. To prevent it causing any issues in the future. Its still doing it.

Its really bad when im just starting out from a stop or trying to creep along at a slow speed while spotting deer. It only does it every once in a while while at 55 cruising on the road though. No problem at all if im wot.

sent while hittin' easy street on mud tires

ghohouston · Sep 19, 2013

Cps or tps

yotaneck13 · Sep 19, 2013

Has new motorcraft cps i replaced that just because it wasnt a motorcraft. And new tps last fall. Just put new window motors in my front windows. So i can check that off my long list lol.

Going to put the old tps back in now and see what happens.

sent while hittin' easy street on mud tires

yotaneck13 · Sep 19, 2013

Swapped back to the tps i took out last fall when i lost my pedal completely. Hasnt cut out yet. Ill see what it does in the morning when i leave for work. Or spotting tonight

sent while hittin' easy street on mud tires