2000 Chevy Blazer Engine stutters at idle with engine warm

Tiny
ONE1963
  • MEMBER
  • 2000 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
My 2000 Blazer will have a stutter at idle once the engine warms up. It happens every 10 to 20 seconds and I get the feeling that it's going to die but it hasn't yet. Anything off of idle seems fine, no miss or hesitation. The fuel pump and filter were replaced at 100,000 miles and new cap, rotor, plugs, and wires at 115,000. It doesn't do it at all when the engine is cold. I'd like to find the cause before it does die in traffic. Because it only does it after the engine is warm I'm leaning towards a fuel or air related problem.
Friday, January 29th, 2010 AT 10:05 AM

4 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi one1963,

Thank you for the donation.

Your description of the symptoms seems to indicate erratic idling causing the problem.

Erratic idling are usually due to dirty Idle Air Control valves and throttle body. I would suggest getting them cleaned and retest.

Is the Check Engine Light indicating while driving? /If yes, get a free scan done at Autozone and let me know the exact trouble codes.
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Friday, January 29th, 2010 AT 11:27 AM
Tiny
ONE1963
  • MEMBER
  • 3 POSTS
No check engine light at any time while running. I can try cleaning but would this cause only hot(normal operating temp) erratic idling? I thought the IAC valve caused more of a cold idle problem. I'll give it a try.
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Friday, January 29th, 2010 AT 11:53 AM
Tiny
ONE1963
  • MEMBER
  • 3 POSTS
Cleaned the Idle Air Control valve, it was a bit dirty, as well as thoroughly cleaned the whole throttle body. Checked for any stored codes, there were none. Still have the erractic idling when the engine is warm. I suppose it could be an ignition problem, just find it odd that it doesn't happen with a cold engine.
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Saturday, February 6th, 2010 AT 5:21 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Sorry for the delay in replying.

The IAc controls the idling speed and when cold, it would increase the amount of air to the manifold to increase the idling speed.

When engine is warmed, if the IAC is not closing correctly, it would cause the surging as it tries to compensate for low or high idling.

Other cause of the erratic idling could be clogged coolant hoses, high idling speed and insufficient coolant in system.
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Thursday, February 11th, 2010 AT 12:24 PM

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