Why does my engine rev when I press the brakes?

This is a vital part of the braking system. The brake booster improves the master cylinder setup utilized to lower the pedal pressure required for braking. If the brake booster has a leakage, it allows additional air into the intake manifold. As a result, the air enters the engine and causes the revving.

Why does my idle drop when I brake?

This may be a sign of a failing idle air control valve. In cases where this valve is clogged or is failing, your vehicle will stall instead of slowing to an idle after the release of the throttle. I recommend having a professional replace your idle air control valve.

How do I turn off the idle stop on my Acura?

The auto idle stop feature can be turned on/off with a button on the center console (TLX, MDX) or left side of the center stack (RDX).

Why does engine stall when brake is applied at idle?

If your brake pedal is stiff and it stalls when you apply the brakes, it sounds like the diaphram in you brake booster may be ruptured. Do what Steve said and pull the vacuum line to the booster and cap it off and see if it still stalls. If it doesn’t stall, then it’s time for a new booster.

When does an idle air control valve malfunction?

As soon as you start your car, the idle air control valve will immediately malfunction. If you happen to be away from home and this happens, the stalling will happen every couple of minutes in the beginning. You should be able to make it to the nearest mechanic in time before the engine stalls completely.

Can a vacuum leak cause engine surging when accelerating?

Vacuum leaks most commonly occurs in the hoses, which is most prone to wear and tear due to the under-hood heat from the engine. Vacuum leaks can cause car surging when accelerating on engines with either a Mass Air Flow system (MAF) or Manifold Air Pressure (MAP) system.