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View Full Version : Help: Fluctuating Idle when Brake Pedal Depressed



ELM'sLX+CHL'sDX
11-17-2002, 12:08 AM
Hi Guys:

Something wacky is going on with my car. Every time I press the brake pedal, my RPMs drop by a small amount. Nothing to stall the car but definitely noticeable on the tachometer. However, if I press the brake pedal several times in succession (like pumping brakes), then my tachometer really drops and I can feel the engine wanting to stall.

Anyone have any idea how I should start trouble shooting this problem? Have any of you experienced this?

Thanks,
Claude

AZmike
11-17-2002, 12:28 AM
Something is wrong with your brake booster. It uses your engine's vacuum to give you power assist when braking. I'm not familar enough with the system to be able to tell exactly what's wrong with it though. If the vacuum hose has a leak (lets extra air in) you'll have an usually high idle so it sounds like somehow the booster is taking some of the air out of the intake manifold.

Check the vacuum line between the booster and manifold first (medium sized hose). There should be a valve inline with the hose. Check that it's installed properly. One side is marked 'to engine' or something like that.