Today my '87 Mustang when I shifted gears, with the clutch in, the RPM actually went up before hitting the next gear. I stopped at a stop sign and at a dead stop the RPM went up to 2200 and wouldn't come down. Stopped at another stop sign, and the same thing. Shut it off, restarted and it was fine. Any ideas? Did the computer just get dumb or is this the first sign of a problem?
Sounds to me like you need a new TPS sensor. It's mounted on the top of the throttle body with two small screws. It's really easy to remove and replace, although you'll need a multimeter to adjust the new one. If you want to do it yourself, just ask we'll post instructions.
The TPS is located directly on top of the throttle body and is adjusted by loosening the two phillips mounting screws and swiveling the sensor until the highest reading is found. It may be necessary to elongate the holes with a small file to achieve the desired reading (though I've never had to elongate the holes).
The spec range for Key On/engine not running is from .88 to 1.0 volt; shoot for the .97 to .99 volt. With the engine running, the voltage should be no higher than 1.05 volts.
The best way to take a TPS voltage reading is by using two safety pins through the wires coming from the sensor. The positive lead is attached to the green wire, while the negative goes to the black wire. Always ground the meter through the sensor's black wire. This gives a direct, and more accurate ground into the computer.
I got the voltage to .98 volts. It seemed to be seeking idle speed with slight up and down fluctuations at idle. I drove it and checked it again, engine off but was hot and the voltage was over 1 volt. Reset it to .95 volts after engine cooled about two hours. After restart idle was steady and after it got hot the voltage read .97 volts. It there a problem with the sensor since heat seems to change the voltage? I'll have to see what happens when it completely cools.
Sorry. No I did not replace it because when I first checked it the voltage was .91 volts so I thought that all that might be needed was to set the voltage.
fock they boot ya out of the dealership for hack work like you suggest
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