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Fluctuating RPM's

Tiny
ABE NEFF
  • MEMBER
  • 2004 FORD TAURUS
  • 3.0L
  • AUTOMATIC
  • 76,000 MILES
New IAC. New air filter. Checked for vacuum leaks. Checked grounds. Cleaned flap inside air flow unit behind throttle body unit. Cleaned mass air flow sensor. High idle when driving. Seems to stick as if if cruise control is on. When started the car sticks at 2000 rpm's longer than it should then drops to a jumpy idle around eight to nine hundred rpm's. If the air conditioner or defrost switch is turned on the car accelerates rpm's upward then drops extremely low and almost dies. If turned back off it will go back to jumpy idle around eight to nine hundred rpm's. If kept on it will completely die. Please help.
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Wednesday, December 21st, 2016 AT 8:13 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is normally always a vacuum leak so we need to start with this guide to make sure this is how you checked for the leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

The next thing we need to do is check the compression and make sure it is even across all cylinders.

https://www.2carpros.com/articles/how-to-test-engine-compression

If it does then we need to move onto putting a vacuum gauge on the engine to make sure there is not an intake valve hanging open.

Please see the chart below for this info on possible gauge reading issues.

Please run through this info and let us know what you find with this.

Thanks
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Saturday, September 11th, 2021 AT 4:23 PM

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