It 95 F250 XL with 351W E40D.

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.

 

bump thread

 

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.

 

That sound could be.

But I just spend think why it do that but it didn't do that when we bought first day.

We wondered that spark plug wires and dist cap we replace with duralast.

Question does duralast cause this issues?

What ohm we need to test spark plug wires? 900 ohm correct?

Throttle body with TPS we try test it say 1.03 but sudden it say 4.03. I hate electric nightmare.

We are plan fix that then sell and get another good f250 or F350.

 

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.

 

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.

 

Where PCM would be? We want try add another ground strap to that PCM.

 

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.

 

Did you ever figure it out I'm having the same problem

 

What was it ?

 

the thread is 6 years old ... OP is prolly driving a chevy by now.

if you need help try starting your own thread, making sure you state which engine, tranny and the specific issue that you have.