High Idle, rpm surges

2002 MITSUBISHI GALANT
380,000 MILES • 4 CYL • 2WD • AUTOMATIC
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FOREIGNLEGEND
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Hello, my car has a really high idle rpm and it surges up and down when I let off the throttle. I just replaced my throttle body and it was perfect for about a month, and now it happens again.

Thank you for your time.
Dec 8, 2017 at 5:57 AM
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STRAILER
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Hello,

This sounds like you have an EGR valve that is leaking causing the engine idle to fluctuate idle speed high then lower.

Here is one guide and one video that will help us do a quick check to confirm the failure:

https://youtu.be/DqUCbbKdWf4

and

https://www.2carpros.com/articles/engine-idles-too-high

Check out the diagrams (below).

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Dec 9, 2017 at 7:14 PM