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Here issues it run great next day when turn off then start it run ok but when hit pothole or stop. It will idle high plus transmission refused shift 3 or 4 gears it just stay 2 gears until it slipping then BANG in 3 gear like you have nitrous in engine.
When we open hood and wiggle wiring harness from driver fender to engine it kind random it work back normal then few sec it went back high idle.
When we bought that truck first day we fill tank and drove home then around town. Mpg was 15.
Now I can't get 15 mpg anymore without random high idle and transmission won't shift correct. I get 9 or less mpg.
Battery light on dashboard finally gone it was bad connector contact on alternator.
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Sorry for my bad grammar.
Currently drive 2000 f350 7.3L XL 4wd auto. mpg vary 15-17.
1999 F250 5.4L 2wd 5.4L auto with over 246K miles. Got used 5.4L with 100K miles. Need find motivation to install 5.4L.
Sounds like bad wiring to TPS.
The computer is getting WOT information more than likely.
It will not shift to 3-4 at WOT and the IAC valve would go wide open.
If the PCM really thinks the TPS voltage is 4.0 VDC that is a major cause of most of your issues. Subford nailed it with his theory of what was going on.
But why it say 4.0 Volts? bad ground or something? We try add new ground strap from body to alternator that seem improve little.
We been on that truck more than we drive. We put almost 200 miles after that now it all issues.
forgot to add
when it say 4.00 volt when we turn throttle to wide open and 4.00 went to 4.96 or 5.00 for wide open. Sudden it went back to 1.03 volt when we wide open it go 1.98.
Why it jump from 1.03 to 4.00 random? It run fine then sudden it happened again then it disappear then it come back again.
__________________
Sorry for my bad grammar.
Currently drive 2000 f350 7.3L XL 4wd auto. mpg vary 15-17.
1999 F250 5.4L 2wd 5.4L auto with over 246K miles. Got used 5.4L with 100K miles. Need find motivation to install 5.4L.
You may have a bad TPS but it alone would not do this.
Other things it could be are:
A bad ground wire either in the wiring from the PCM to the TPS or a bad PCM ground wire at the radiator support where the small black wire from the NEG Post of the Battery hooks to the body.
A bad 5 Volt supply in the PCM but not as likely.
Bad pins in the PCM or TPS plugs.
A ground strap will not help you.
The ground for the PCM comes in on pins #40 and #60 of its PCM plug.
The PCM is located in the drivers kick panel but you can only get to it from under the hood.
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