Engine shakes

Tiny
MIKE OTIENO
  • MEMBER
  • 1998 MITSUBISHI CHARIOT
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,874 MILES
The engine shake and the rpm is going up and down as if it wants to go off.
Thursday, January 10th, 2019 AT 11:33 AM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,872 POSTS
Hi and thanks for using 2CarPros.

If the check engine light is staying on when the engine is running, start with scanning the computer to identify diagnostic trouble codes. Here is a video which shows how it is done:

https://youtu.be/YV3TRZwer8k

If this is happening mostly at an idle, I have two things I would recommend checking. First, and my first suspect, is an engine vacuum leak. Here are the directions for testing for a leak. Follow the directions to determine if this is a problem.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If there are no vacuum leaks, I recommend checking a component called the idle air control valve (IAC). The IAC is responsible for maintaining the engine idle speed. Unfortunately, this vehicle wasn't offered in the US, so I don't have specific technical information to provide, but the IAC is located on the throttle body and is an electrical component. Often times, when they go bad, the engine idle speed will loop up and down. Here is a link that shows in general how an IAC is replaced:

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Also, make sure there isn't excessive carbon or dirt on the throttle plate. Here is a link that shows how one is cleaned:

https://www.2carpros.com/articles/throttle-actuator-service

Here are a link that discusses engine surges. I thought it may be helpful.

https://www.2carpros.com/articles/engine-surges

Let me know if this helps or if you have other questions.

Take care,
Joe
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Thursday, January 10th, 2019 AT 2:39 PM

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