5.0 swap - throttle position sensor P0122 code - rough shifts


mimswk

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I have a 99 4x4 with a 5.0 swap from a 96 Explorer. The previous owner seems to have replaced the TPS plug and put in a new sensor. It has a P0122 code.

The engine harness is from a 99 Explorer - not sure if that makes a difference in this case.

I've tested the sensor - it does have low input voltage (.87 volts - throwing the P0122) but seems to increase and decrease back down smoothly when opening and closing the throttle body. Tapping on it while opening/closing the throttle does not seem to cause any erratic behavior. Wide open reading is around 4.5 - 4.6 volts. Reference voltage seems fine.

I'm experiencing pretty weird shifting - longer shifting on acceleration, crappy downshifting causing bogging, etc.

I know the TPS can cause all sorts of shift issues. Would simply having the low input voltage throw everything off?

The sensor doesn't seem to be adjustable - it does feel like there's tension when I install it. I'm hesitant to waller out the holes and adjust it so it gets close to the 1 volt signal needed so it doesn't throw the code.

I'm not completely ruling out that my transmission (not sure of the model - automatic from an 01 Mountaineer) needs some attention. Just trying to take care of the most obvious issue to fix (TPS stuff) before going that route.

I do have it temporarily wired up - I wouldn't think that I'm having a voltage drop due to that. But maybe?

I really don't like just throwing parts at things if I can help it. Not sure if a new TPS would correct the issue.

Any tips or suggestions?

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franklin2

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The guy in my book says to take a jumper and jump the 5v reference voltage to the signal wire. Then see if the first code you got goes away, you should get the tps voltage is too high code. Just to verify the wiring and the computer are working correctly.
 

mimswk

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The guy in my book says to take a jumper and jump the 5v reference voltage to the signal wire. Then see if the first code you got goes away, you should get the tps voltage is too high code. Just to verify the wiring and the computer are working correctly.
Thanks, Franklin. I may give that a shot. What book are you referencing?
 

franklin2

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