| bluesuburbansky |
Just wondering... :dunno:
Something I noticed lately about my car...the idling speed seems to change depending if the brake is being used or not when the car is at a stand still. For example, if I'm sitting at a red light with my foot on the brake the car idles faster and less smoothly - so much so that the gear shift is visibly vibrating. If I take my foot off (you know when it's flat enough to not roll), it idles slower and smoother.
Is there an explanation for this - is it indicative of a problem? Or is it just another one of the many quirks of my stupid car? :confused: |
|
|
| sparkycivic |
when you push on the brake pedal, the brake booster uses some of the stored vacuum in it to push on the master cylinder and operate your brakes. This causes some of the vacuum pressure to be lost, so it gets replenished by the engine. This is effectively letting some air into the engine's intake manifold(the vacuum source) , so the engine will speed up since it's like you're opening the throttle a little bit every time you step on the brakes. Also, since the throttle position sensor still shows that it's in the closed position, the timing and mixture won't be correct, so the engine will probably stumble a bit for the unexpected airflow. normally touching the gas pedal causes an extra flow of gas by some correction factor to prevent it from stumbling, but since the throttle stayed shut, it gets no extra shot of fuel, and stumbles.
is this effect is getting worse, then i would suspect that the brake booster is leaking, or else there is some other vacuum leak related to the brake booster line
did that help you? |
|
|
| bluesuburbansky |
quote:
Originally posted by sparkycivic
is this effect is getting worse, then i would suspect that the brake booster is leaking, or else there is some other vacuum leak related to the brake booster line
did that help you?
Yes, that helps! Thanks!
It isn't getting worse BUT I haven't owned this car for very long. Reason I was wondering was because I've never noticed such a difference in any other car I've driven.
Let's say I have a leak somewhere...is it pretty important to fix and is it an easy fix or not? |
|
|
|
