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2000 Blazer 3000 rpm idle

Discussion in 'GM Powertrain' started by TJbear, Jul 14, 2011.

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  1. TJbear

    TJbear New Member 100 Posts

    A friend has a 2000 Blazer w/4.3 with about 100K miles. When it's started cold, it idles at 2000 rpm and then slowly increases to about 3000 rpm after a minute or so. It is running on all cylinders and seems smooth otherwise. We removed the TB and IAC and cleaned them up but it didn't help at all (didn't think it would but the TB needed cleaning anyways). I know the IAC could just be defective but he's now trying to avoid throwing parts at it. Somewhat recent parts replacements include the cap and rotor, ign module, and the MAF sensor. It had been running rough and stalling before. Then it sat for about a year and now this crazy idle problem. Any ideas? Thanks!
  2. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts 100 Posts

    Have you checked for cracked vacuum hose's? A cracked hose can drive you crazy.
  3. murdog94

    murdog94 New Member 1000 Posts 100 Posts

    I second that.. Also is the CEL on?? i have had several of the 4.3L vortecs and if the CEL is on you will want to read the codes for sure!
  4. TJbear

    TJbear New Member 100 Posts

    We checked for bad hoses. Didn't find anything but it's sorta cramped and hard to see under there.

    He did say the SES light has been on before but he hsan't been running it long enough for it to come on again because it's idling so high now. I think it was a cat converter efficiency related code.

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