Anonymous asked in Cars & TransportationMaintenance & Repairs · 8 years ago

Rpm's bouncing up and down. Bad TPS?

Ok. So I have a 2000 Olds Alero 6cyl. Its had some problems over time. ( don't advise buying one ) The most recent problem is the rpm's started bouncing up and down out of the blue and sounded really rough. Was hearing a hissing sound coming from the motor as well. Found the air leak. Was a vac hose that handled the air recycle for the air in the car. That didn't fix the rpm problem. Cleaned out the throttle body and put in a new idle air control valve. Checked the coils. Rpm's were still bouncing up and down but then just by chance.. I turned on the A/C.. The idle leveled off and ran just fine. Drove it around the block a few times and it runs fine, but when the a/c (or possibly just air) is OFF the rpm's start bouncing up and down again. Could this be a bad TPS Throttle position sensor? Any help is much appreciated.

1 Answer

  • 8 years ago
    Favorite Answer

    That's not the way TPS fails. They develop a flat spot where the engine stalls or hesitates at the same spot every time. 99.99% of the time you have a hunting idle, it's a vacuum leak. Read this post on why it happens--skip the part on IACs

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