RPM gauge

2008 GMC SIERRA
95,000 MILES • V8 • 2WD • AUTOMATIC
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MELANIEV
  • MEMBER
  • 2 POSTS
What does it mean when the RPM gauge moves back and forth while driving.There is no noticable sounds in engine while this is happening. Engine sounds fine.
Feb 2, 2011 at 12:19 PM
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BILLYMAC
  • ✓Experienced Mechanic
  • 2,204 POSTS
This could mean a couple things . either you have a eng misfire which is doubtful as your onboard computer would set a misfire code.

the other possibility depending on where you live could be ice on the road. if no ice where you are could be a prob in the ignition system causing an inaccurate tach reading. and the final possibility is simply a defective tach guage..
Feb 2, 2011 at 12:52 PM
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MELANIEV
  • MEMBER
  • 2 POSTS
How would I know if there was a problem in the ignition system?
Feb 2, 2011 at 1:07 PM
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BILLYMAC
  • ✓Experienced Mechanic
  • 2,204 POSTS
blank response
Feb 3, 2011 at 6:24 AM
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