7 reasons why an automatic car stalls when a gear is engaged

What mechanics mean by the term “stalling” is when the engine stops running and the car stops immediately. This can happen anywhere, even on the highway. For first-time victims, it can be confusing and embarrassing.

Automatic cars stall due to reasons like an empty fuel tank or just a faulty alternator. The most recommended remedy for frequent car stalling is consultation with an expert who will identify the cause and deal with it in time.

If the problem persists we suggest you get rid of the car before the underlying problem lowers its resale value.

There are several causes of engine stalling in automatic cars and a few solutions which you can try before moving to more drastic measures.

All this is to answer the question, why does an automatic car stall when a gear is engaged?

1. A Discharged Battery

As stated above, a bad alternator causes stalling. One of the main reasons your alternator is having issues is a low-performing battery. If the battery is bad the car might not even start and if it does it will ruin the alternator in due time.

You might have had to deal with a faulty battery once or twice, it’s not a big deal. Things get out of hand when the car stalls and you have a bad battery, this is a clear sign of trouble. You should buy a new battery and have the alternator checked.

2. The Fuel Mix Is Not Adequate

When the air and fuel mixture is not enough, your engine will have issues. The alternator might even fail. The poor performance of parts like the alternator will result in a damaged engine and the signs will be very clear from the dashboard lights.

Another way to tell that your engine is stalling due to a low fuel mix is a low battery. Get a mechanic to check the car, replacement might not be cheap but it will be worth it.

3. A Faulty Fuel Pump

A car runs on fuel and if it can’t get enough of it to the engine there is no way it can function. A damaged fuel pump means low or no fuel is getting to the engine resulting in weak engine performance.

If the problem goes on for a few days you will notice some stalling after you engage the gear. You are advised to check the fuel pump if your car starts stalling. If it is damaged, replacement is quick and relatively cheap.

4. A Failing Torque Converter

This is a component present in every automatic car. It works to replace the clutch in the automatic transmission system. Its role in the proper functioning of the car cannot be ignored.

It is responsible for keeping its engine running even at a stop by managing the transmission fluid. It fails; you can expect the car to stall.

It fails because of reasons like dirt in the fuel and overheating. It might also fail due to inadequate stall speed. To ascertain the condition of your torque convertor you can perform a simple stall-speed test.

  • 1. Confirm the car’s RPM and locate the tachometer. If you have issues, all this information is available in the owner’s manual.
  • 2. Immobilize the car, use the parking brake, and place objects under all the wheels.
  • 3. Step on the brake, start the car, and Shift gears repeatedly without releasing the brake.
  • 4. Step on the accelerator for 5 seconds with the brake pedal still on the floor. As you do this, check the tachometer readings for any abnormal figures. After the readings release the pedals starting with the accelerator and then the brake.
  • 5. If the tachometer numbers were wrong you can visit an auto repair shop and get the torque converter fixed in no time.

5. Car Idle Circuit

This part aids in the car’s combustion process by supplying oxygen when the car is in stall mode. When it is broken the oxygen supply will be interrupted and this can affect your engine if it is not managed early enough.

Checking the car idle circuit is a good idea when your car stalls. If the problem lies there you can always have it replaced.

6. The Air Filter Could Be Jammed

The air supply is important if a car is to function properly. If the filter has issues, the airflow will be interrupted and the car will stall. To save you from the problems that come with jammed filters, you should regularly check the filter and keep it protected from particles like dust and leaves.

7. Low Fuel Pressure

This is a major cause of stalling in automatic cars after engaging the gear. It results from blocked injectors. This happens when the system is fed dirty fuel and gets clogged, the pressure at which the fuel flows reduces and the result is low power and stalling.

To solve this problem you can opt to replace the injectors and clean the tank.

What Should You Do When Your Automatic Transmission Stalls?

A car stalls because something in its system is not working right. The first step in dealing with a stalling car is identifying the cause. Check the various areas in the car that might result in stalling like the tank, clutch, and battery.

If any of them is damaged get them fixed. If the problem persists, move to the more sensitive areas like the alternator and injector. Check for damage and clogging and fix if any.

You can have an expert run some tests and offer you a conclusive diagnosis.

Can Low Transmission Fluid Cause Stalling?

Yes, low transmission fluid can cause your car to stall. This mostly happens at red lights and other spots where you have to stop for a few seconds.

It might not be serious and the car might start immediately but there is a need for you to have it checked. The transmission line might be faulty. The cost of repairing the transmission lines might be high but not as high as when you need to replace the entire transmission.

Bottom Line

When an automatic car stalls, the possible causes are many but the good thing is that most of them have ready remedies. Some costly repairs might be needed but that should not discourage you from taking care of your car.

The most important step when dealing with such an issue is understanding the causes or sources.

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