GMC Sierra rough idle

  • 1 POST
  • GMC C1500

I have a 2002 gmc sierra 1500 5.3L with approx 70,000 miles. When I crank the vehicle in the mornings and drive for a couple of miles, I notice that when I stop, the idle pulsates. This tends to happen on mornings where the temperature is below 50 degrees. I had some check engine codes come up. P0171, and P0174. These are both bank 1 and bank 2 too lean. I took it to a mechanic and they said it was a loose snorkel tube. Thought everything was fine. Pulsating has returned, but no check engine lights. The truck feels like a muscle car with an oversized cam. It lurches against the brakes when I am at a stoplight. I have heard that it could be an intake manifold gasket. $$$ I am hoping someone can give me some other options.

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have the same problem?
Wednesday, February 28th, 2007 AT 11:28 AM

1 Reply

  • 1,395 POSTS

It could be a leak at the intake with the lean codes, you could do the old backyard spray aound the engine to see it it idles different when thespay is applied and maybe check the idle air control motor on the throttle body when they faile they have the same effect on the idle

thanks, jim

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Wednesday, February 28th, 2007 AT 12:32 PM

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