Skip the auto shop - Our mechanics make house calls

Q: Stopping lowers the RPMs

asked by on

The RPMs lower when the brakes are applied.

A: When a vehicle is running all of the access...

When a vehicle is running all of the accessories and systems used to run the motor all put load on the system. This being said, anything from turning on your headlights to depressing your brake pedal puts extra load on the engine. The modern brake system can use a vacuum booster system to provide a nice smooth brake pedal feel. It does this by using vacuum supplied by the motor while running. When applying the brakes, the vacuum booster uses supplied vacuum from the motor to provide a easy brake application. Doing so puts a load on the motor causing a slight drop in rpm. This is a normal response. Unless there is already a large load on the motor causing the added load from the brake booster when the brakes are applied that the engine starts to stall or smoke. The only way to find out whether this is normal or if there is an issue would be to have the vehicle inspected by a certified mechanic.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: When the AC is turned on my Check engine light comes on , code reading throttle position sensor, not enough voltage.

If you have the electronic type throttle that has no cable to the throttle body, then you will need to check to make sure that battery voltage is not dropping below 12.5 volts when your A/C is turned on. You...

Q: What does it mean if the Brake System Light comes on in the dash?

Of all the safety systems built into your car, the brakes are the most important. While the Brake System indicator should come on during startup, it should go out after a few seconds. If it does not, or if it...

Q: Dashboard blistering

Hi. The only way to repair a blistering dash board is to replace it. Alternately, you could push a dash board cover over it to hide the cracks. Covers such as these are sold online and at auto parts stores....

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...