Car starts at full throttle

GOTTAKEEPMOVIN'

MEMBER
2008 CHEVROLET COBALT
2.4L
6 CYL
2WD
AUTOMATIC
194,000 MILES

When I start the car, the car immediately revs up to approximately 3800 rpm's. No codes stored. Not sure what to do to get it to stop. I am tempted to say it may be throttle position sensor related, but not certain. Today I started the car again and it runs at 800 RPM without a problem. Still, no codes stored. Could be just me but it tends to act up when the car's been rained on.I am afraid this car is pretty much an undependable ride if I can't figure out what this intermittent issue is. Any hints or suggestions would be greatly appreciated! Thanks, in advance!

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

It sounds like you have a larger vacuum leak or the throttle actuator is going out. Here is a couple guides to help you find and fix the problem.

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

and

https://www.2carpros.com/articles/how-a-throttle-body-works

Sometimes when they go out it won't set a code but not very often.

Please let us know what happens.

Cheers, Ken

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Wednesday, October 25th, 2017 AT 7:06 PM

GOTTAKEEPMOVIN'

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41 POSTS

After checking all vacuum lines, I decided to clean the throttle body as well as possible (albeit while still "on" the car) as much as possible. After having done that and driving the car for a couple of weeks to relearn the idle, the codes have not come back at all. Throttle body is clean and appears to be working properly at this point, so I will see how long it lasts. Thanks so much for the pointers!

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Sunday, November 19th, 2017 AT 12:22 PM

KEN L