Something odd
Thread Starter
Staging Lane
Joined: Jul 2006
Posts: 81
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From: Atl. ga
Something odd I just noticed something strange on my car today. Sitting in car with it idling in park if I put my foot on the brake pedal and let off I hear the engine idle change. I can't see it on the tach though. The rpm goes up a little when I let off the brake pedal. Any of you experiencing this? Thanks.
Joined: Nov 2001
Posts: 34,632
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From: Schiller Park, ILL Member: #317
The power brake booster is connected to engine vacuum via a line from the intake. There will be a slight change in engine vacuum when the brakes are applied/released due to a draw from the booster. This would explain a slight, momentary change in idle speed. Should be very, very minor though.
Can't say I've ever paid any attention to this on my Camaro, but I've noticed before on my Bonneville if I pump the brakes 3 or 4 times with the car idling in park the idle will jump around enough to even move the tach needle a bit.
No big deal really.
Can't say I've ever paid any attention to this on my Camaro, but I've noticed before on my Bonneville if I pump the brakes 3 or 4 times with the car idling in park the idle will jump around enough to even move the tach needle a bit.
No big deal really.
