Q: My car keeps cutting off when I put it in reverse and sometimes when it idles.

asked by on

So sometimes when I put it in reverse it cuts off and when it idles. My girlfriend was going 45 and the engine cuts off. It's not a bad alternator cause I check that. The spark plugs have been replaced. So I knows it's not those two things. I'm thinking it's a bad fuel filter or fuel pump. Maybe a bad air filter. Oh another thing. When I hit the gas the engine cuts off for a second and starts to move the car.

My car has 150000 miles.
My car has an automatic transmission.

Hi There, Based upon what you are describing and how the car responds to load, it sounds like you may have a faulty MAP sensor. The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the [MAP sensor]((https://www.yourmechanic.com/services/manifold-absolute-pressure-sensor-map-sensor-replacement), it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My car keeps cutting off when I put it in reverse and sometimes when it idles.

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: My car still overheats, I replaced water pump and thermostat, and now after water pump install it knocks bad

Hi there: Trying to diagnose an overheating issue remotely is incredibly difficult. However, there are three things you can do to attempt to solve this issue. First, remove the water pump, verify it's the right replacement part and reinstall with...

Q: Low idle when stopped unless the a/c is on or i shift into neutral

Due to the change in load put on the motor when shifting into gear vs neutral and the change in load when the a/c is on vs not on, this may suggest you have a bad MAP sensor. Both of...

Q: Ford F150 burglar alarm goes off for no reason

Factory- installed and aftermarket alarm systems function in a similar manner. Factory systems may be easier to diagnose because often, the system is accessible with the proper scan and diagnostic tools. Almost like a fault code for engine performance can...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.