I have searched this forum for weeks reading every post about TPS I could find but I now must ask a question, I hope it is not to dumb of a question as I am a rookie.
I just installed a 91 TPI unit (730 ecm) on a fresh 350, I have replaced most of the sensors with new but it will not run correct. If I unplug the IAC the car idles fine at about 650rpm, turn off and plug the IAC back in it runs at about 1100, turn car off and turn back on it goes to about 2200. I ran DataMaster with the ignition on and the TPS reading shows 100% so pushed the gas pedal to the floor and it went to 0%, IS this normal? I would think it should start at 0 and go to 100 when it hits the floor. I have set the TPS to .54 and it has not made a difference, sorry for the long winded post put I am out of ideas and must consult the experts on the forum.
Thanks for any input.
RB

 

What does the TPS read if you start the car (without hitting the gas)? If the TPS was really showing 100% during crank, the car would not start (it would go into Clear Flood Mode).

As far as the idle, if its erratic and high, then it could be either the IAC or ECM. These IACs are known for failing, because they have a plastic worm gear that tends to wear out (or break), causing erratic idle. On my '91 'vert, I ended up replacing the 730 ECM when I had the same symptoms and a new IAC didn't fix it. Turns out the driver inside the ECM failed causing erratic IAC operation.

 

It still shows 100% when it is running, and it will only start if I put the pedal on the floor then it is very difficult, the tps volts goes the opposite also, goes down as the pedal is pushed. I have another computer so I will change computers when I get a chance. So the 100% tps could be a computer problem rather than wiring?
Forgot to mention that I replaced the IAC and cleaned the throttlebody per Vader's instruction on this board.
Thanks again,
RB

 

I would have to say that you either got the wrong TPS, its installed incorrectly, or its bad. You are correct in the sense that its operating backwards. It should indicate 0% with the gas pedal released and 100% at WOT.