Car stalls when braking or idle

Maintenance/Repairs
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1

Hi,

This does not happen all of the time. But enough now that there is something wrong.

When I need to apply my breaks my car will stall. Or sometimes when I am idle at a stop light my car will just stall on me. Each time this has happened I put the car in N or P and start it back up and away I go.

I have no idea where to start troubleshooting this problem.

Car is a 98 Pontiac Sunfire GT with about 150,000m

Thanks for any help.

2

You didn’t mention how the car is running in general - e.g. whether or not the idle is nice & smooth and it runs well when the brake is not involved. I’ll just assume the car is otherwise fine and suggest that you have a problem with your power brake booster or its check valve. As such operating the brakes creates a sudden, massive vacuum leak - enough to stall out the engine.

3

To add a little to cigroller’s comments I would suggest that I would be very careful. If the brake boost is in question, and it certainly is, you could suddenly find it very difficult to stop your car. This is something you want to have inspected and corrected before you continue driving the car.

4

I agree that this situation could be caused by a defective power brake booster.
Since total failure of the booster is not something to take lightly, this definitely needs to be checked out by a competent mechanic, i.e.–NOT the guys at Midas, Meineke, Monro, Sears, Pep Boys, or any other chain operation.

Another possibility is that the Idle Air Control (IAC) is defective. While an IAC problem is not dangerous, I wanted to give you another possibility just in case your mechanic finds that there is no problem with the power brake booster.

5

Thanks for all the info. The car in general runs well!
Just to try and understand what is going on I was looking through my Chiltons manual and could not find anything on a brake booster, does it go by another name?
And also on a side note, this morning my check engine light came on.
I appreciate all the help!!

6

Your CEL could be referring to a “lean condition detected” code set by the PCM, which is in alignment with your bad vacuum brake booster. For sure, don’t take the vehicle on any trips and drive it like you have no brakes.