1989 Grand Prix Accelerates by itself

Tiny
TOADSTER
  • MEMBER
  • 1989 PONTIAC GRAND PRIX
I have a 1989 Pontiac Grand Prix LE 3.1L with 113000 miles. When the car is not moving the idle is very rough. The RPM will go below 500 and then spike back up to 1500. When the car is moving faster than 5km/h the car will accelerate on its own rapidly. When the car accelerates on its own, the RPM is usually between 1500 and 2000. It is almost as if the gas pedal is being pushed down. When the car is moving and then put into neutral, the RPM will spike to 3000 and stay there until the cars speed is less than 5km/h. Nothing is pushing the pedal down and I have disabled the cruise control by detaching the cable that leads to the throttle.
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Saturday, September 15th, 2007 AT 7:16 PM

1 Reply

Tiny
RASMATAZ
  • EXPERT
Sounds like the TPS and IACV. The TPS tells the computer whether the throttle plate is closed or open, the IACV tells the computer the current speed and computer refines it as necessary
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Saturday, September 15th, 2007 AT 8:56 PM

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