Yeah, I agree!

I will check the brake booster line and check-valve tonight when I get home.

I have not adjusted the brake pedal or changed the master cylinder. I have, however, performed a front brake job consisting of new pads, rotors, and bleeding of the brakes. But, the brakes work flawlessly!

Question though - while I repeatedly press and let go of the brake pedal while stopped and idling at a stoplight, shouldn't something compensate for the 'extra' vacuum that is demanded by the brake booster? In other words, as the vacuum demanded to the booster increases as a result of pushing the brake, should the motor attempt to idle faster momentarily to compensate? I keep leaning toward a bad IAC, since this is what i think controls the idle, but not sure if these things go bad without setting a code. Any thoughts?

Thanks again,

Anthony

 

Whatever you did to the brakes, that was down at the wheels. Shouldn't have caused anything like this.

Yes, the IACV should compensate. Actually, it should close up, because a vacuum leak gives MORE air to the engine, not less. So the "normal" behavior is that a sudden small vacuum leak would increase the RPM just as if you'd tapped the gas pedal a little bit. So it's a bit confusing, but you've narrowed it down to the brakes.

Spray some throttlebody cleaner & clean out the throttle body bore, throttle plate (especially where the throttle plate closes against the bore). Clean out the IACV. Not sure if that'll fix it, but that stuff should be kept clean anyway.

 

Quick update here...

I checked the brake booster hose last night. Found no signs of leakage. Also checked the other lines leading to the throttle body for leaks but all were fine.

This morning, however, my CEL came on. So off to the auto parts store I go to find out what code is being set. Will let you know whata I find out.

Anthony