When idling the engine randomly revs from 800 RPM to about 1,600 RPMs?

Tiny
BOOGALOO
  • MEMBER
  • 2002 SATURN L200
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 177,000 MILES
This happens when it is in gear at a stoplight and requires me to throw the transmission in neutral (and then back in gear when the light turns green) or put my foot firmly on the brake while the engine strains against the transmission trying to move the car forward. Recently we replaced all four spark plugs and the ignition coil assembly. Last year the BCM was replaced. This engine idle speed issue is relatively recent, prior to the ignition coil replacement. At that time the engine was running rough. It accelerates smoothly and when the idle runs up and down the engine is smooth. Throttle body problem? Mass air sensor? Vacuum hose leak?
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Sunday, August 13th, 2023 AT 9:13 PM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,235 POSTS
The first thing we need to do is run the codes, this guide will help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I have seen the IAC valve go out causing this issue. Here is a guide that may help as well:

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

I would service the throttle body and IAC valve.

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

Check out the images (below). Please let us know what happens.
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Monday, August 14th, 2023 AT 5:57 PM

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