RPM’s fluctuate while idle gmc 2009 v8-4.8l sierra 1500

Q: RPM’s fluctuate while idle

asked by on November 11, 2017

My RPM’s fluctuate between 1000 and 1500 while idle around 45 mph. It goes away when accelerating/decelerating. It started a few months ago, but occurred rarely. It does it every time I’m at this speed now.

My car has 95000 miles.
My car has an automatic transmission.

Hi Tyler. Thanks for sending in your question tonight. Assuming your AC is turned off, this type of problem can occur due to a few different issues. The most common reason is that the idle control valve is sticking or damaged. A dirty or clogged throttle body and fuel injectors can also cause these issues. It’s also possible that the fuel filter is dirty and needs to be replaced. If the AC is turned on, this is actually rather normal, but existing issues like the ones described above can make the idle issues appear worse.

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