why cant i adjust my tps?

[94gts]

so my car is still sitting in pieces because i hit a deer a few weeks ago so when i get bored i find things to do. well today i decided to check my tps and for some reason it is at 5.01V closed and does not budge even when i move the blade. the reading also does not move when i move the sensor either. yes the key was on and the car was off. What gives ?

 

[1TallMF]

You are probing the wrong wire. That is the 5V refference voltage from the computer. On the TPS connector, the top wire is ground, the middle is the signal, and the bottom is refference voltage. You want to probe the ground and signal wires. It should be anywhere between 0.6 - 1.0V, but not higher. It is arguably pointless to adjust the TPS on our cars.

However, if you actually were probing the two top wires, and seeing 5V there, then something is deffinetly wrong.

 

[1slow95]

Yeah, it sounds like you're just on the wrong wires.

Also, I don't think it's pointless to adjust the TPS. Mine was waaay off(reading .5v) and I was having some strange problems with the car that were probably TPS related. But, as long as it's between .9 and 1.0, I don't see any reason to adjust it.

 

[1TallMF]

I thought I read somewhere that the 94-95 computers read the TPS voltage at startup and automatically refferenced that as being 1.0V, for example, if the TPS value at startup is 0.9V, then the computer would add 0.1V to the entire operating range, so a part-throttle value of 2.55V at the sensor would convert to 2.65V to use as a value in the load tables. Maybe I'm totally off my rocker on this one, but I coulda sworn one of the fine chaps on here explained this before.

 

[Stanger007]

That's been my observation by watching my twEECer is that the EEC sets the voltage at startup and automatically sets the TPS to 1v.

My Fox (A9L EEC) wasn't like this - had to manually set the TPS w/ a voltmeter.

 

[1TallMF]

Thanks for the backup info, 007. I was hoping I didn't just pull that out of my @$$


:SNSign: FTW

 

[HISSIN50]

The fox TPS does internally zero-out upon start-up as well.

 

[94gts]

You are probing the wrong wire. That is the 5V refference voltage from the computer. On the TPS connector, the top wire is ground, the middle is the signal, and the bottom is refference voltage.

ah **** me. i guess i was wrong to assume that the wire with the black was the ground. dumb ford

 

[bill302]

So to test a 94-95 car you would put the negative lead on your voltmeter to a good engine ground or the first grey wire. Then you would put the positive voltmeter lead to the middle grey with white stripe wire. If you need more help look at the image below...copied from link below...

http://www.muscularmustangs.com/tps.php