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My Car Wants to Kill Me

My car speeds up on its own. It can get up to 75 mph on its own without me touching the gas pedal. There is no pattern to its speeding up problem–it does it on interstates, back roads, when slowing down, when intentionally speeding up, air on, air off, etc.

This has been happening for over two years. It’s been to the dealership (they can’t figure it out) and to multiple local mechanics (who also can’t figure it out).

The throttle body has been cleaned, the idle air control valve has been replaced, and multiple hoses have been replaced in case they were clogged. Nobody knows what else to do with it. Please help!

What year?

Something is telling the injector(s) to open up. Prime candidates are the temp sensor, a throttle position sensor and the manifold absolute pressure sensor. But it’s impossible to test them from here. These could do this without tripping a fault code.

Does it do this only when the cruise control is on perhaps?

It is a 2001.

No, the cruise control has been disabled as well since they thought that may have been the problem 2 years ago.

You have been driving this car in this condition for 2 years with no resolution to this safety hazard? Yikes!

This sounds like a perfect candidate for Cash for Clunkers, as long as it fits the mpg parameters. You wouldn’t want anyone else to be exposed to this car, so putting it through a crusher and giving you $4,500 might be a good thing.

How often does this problem occur? You have something letting air into the intake manifold, either through a stuck open throttle body or a large vacuum leak.

Do you hear any hissing when it happens? I don’t like to guess when replacing parts, but it may be worth it to get a new power brake booster since that is one of the few possible sources of a big vacuum leak.

It happens about once every two weeks.

No, there’s no hissing when it happens. There’s no noise or indication that anything is wrong, except for the speeding up. When it happens I usually have to throw it into neutral and the RPMs skyrocket until it stops, which doesn’t take long once its in neutral.

Before it stops there’s a loud pop, and then it’s back to normal for a couple of weeks.

My guess would be a bad throttle position sensor.