High Idle, rpm surges

2002 MITSUBISHI GALANT
380,000 MILES • 4 CYL • 2WD • AUTOMATIC
Avatar
FOREIGNLEGEND
  • MEMBER
  • 1 POST
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 7, 2017 at 9:57 PM
Advertisement
Avatar
STRAILER
  • ✓Experienced Mechanic
  • 55,065 POSTS
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
Image (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Dec 9, 2017 at 11:14 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.