RPM? Unstable will not pass smog.

Tiny
FRANK WIEST
  • MEMBER
  • 1995 FORD MUSTANG
  • 4.3L
  • 6 CYL
  • 2WD
  • 120,000 MILES
When you hook the car to the smog machine the rpm levels are very unstable. They jump all over the place. Will not allow machine to test car smog.
Saturday, April 15th, 2017 AT 1:35 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,702 POSTS
Hello,

This happens when there is a large vacuum leak somewhere, here is a guide to help you get the problem fixed.

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

Please let us know what happens.

Best, Ken
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Monday, April 17th, 2017 AT 4:33 PM

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