Skip the auto shop - Our mechanics make house calls

Q: Stalls when stops

asked by on

Replaced alternator and idle air control valve. Trying to figure out what to check next.

My car has 195000 miles.
My car has an automatic transmission.

Hi There, I would recommend checking the MAP sensor as it sounds like the vehicle responds adversely to changes in engine load. 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?

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

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: Oil pressure and battery light stay on when ignition is off.

Hello. If this is occurring, then there is a short in the electrical someplace. Most of the time, the issue is in the ignition switch. The switch fails internally and causes some circuits to stay on which will drain the...

Q: Squeaks when driving over bumps

The suspension is the most likely source of the noise. However, almost anything on a car can develop a squeak. Try your best to narrow where exactly the noise is coming from. Front, back, left, or right. This will help...

Q: Cam shaft sensor

It sounds like you have multiple problems going on. The camshaft sensor can set a fault code if it is not turning. If it's not turning, it's most likely from a broken timing belt. If the timing belt broke, then...

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 to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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.