1996 Chevy Blazer rough idle

Tiny
JB5537
  • MEMBER
  • 1996 CHEVROLET BLAZER
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 166,000 MILES
Blazer starts fine then goes immed to a rough idle. Giving it gas and getting rpms up will smooth it out in a minute or so. Black carbon smoke from tailpipe on warmup until it is smooth. Going back to idle it gets rough again. Possible iac valve?
Thursday, January 28th, 2010 AT 6:54 AM

1 Reply

Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Do you have a check engine light? If not is it working (when ign. Is turned to on, light should illuminate).

This is most likely a sensor out of range, like coolant temp sensor for example.
Black smoke indicates a rich mixture and most sensors responsible for air/fuel will go to a default rich setting if bad.
This is done to prevent a lean mixture which can cause severe damage to engine.

If light is on get codes read at most autoparts stores for free.
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Thursday, January 28th, 2010 AT 9:08 AM

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