Sometimes your car can just turn off while driving for “no reason at all” when In fact, this behaviour has strictly defined reasons. As experience shows, in most cases, they are also quite simple. However, there are other, less common reasons, which are still found quite often in the automotive industry. Let’s talk about all of them.

Normal engine running conditions

Your internal combustion engine requires:

  • A constant supply of air, in the appropriate proportion of the fuel
  • Properly operating nozzles (injectors)
  • Correct ignition angle
  • Proper functioning sensors and actuators of the engine control unit
  • Required compression
  • Functional spark plugs.

To sum it up, an engine needs air, fuel, compression and ignition.

In terms of the probability regarding the failure of the internal combustion engine, gasoline engines are more vulnerable, because they have an additional system – a high-voltage ignition unit (spark plugs), which are very sensitive to weather conditions.

Reasons why the car turns off while driving

If the engine was running normally while the car was moving and suddenly the car stalled, the following may have happened:

1. Low Fuel:

Indicating Low Fuel

Sometimes the car will stall on the move during a sharp acceleration with little fuel in the gas tank.

Why does that happen? Because the tank in your car can be horizontal, and even 10 litres of gasoline form a thin layer.

At sharp accelerations, especially on an ascent, the fuel is pressed against the back wall of the tank, the fuel pump picks up the air and the car stops.

Since fuel consumption is maximum during acceleration, the pressure in the fuel rail drops almost immediately and the engine stops.

Once the car has stopped, the engine starts without any problems.

Faulty IAC actuator:

Image Of a IAC Actuator

Statistics show that the failure of the IAC actuator, which is responsible for the corresponding engine speed, is the most common cause of a stalling engine.

Of course, such a failure can only be true for the injector motor.

What To Do: Make sure that the IAC actuator is working properly by turning the crankshaft with the starter with the gas pedal pressed out at the same time.

If the engine starts, but the number of revolutions increases, then the IAC actuator is broken.

The problem is solved by replacing the part.

Faulty Ignition Coil:

If one of the spark plugs is flooded or one of the high voltage wires is punctured, the engine usually does not stop.

However, if the ignition coil (if it is single or twin) is punctured when it heats up, the car may stall periodically and then start again after a while.

Sometimes the coil has micro-cracks. In wet weather, moisture can get in there and the car can stop suddenly.

Sometimes rainwater will flood the ignition system in a rainstorm or puddle. Then, as it dries out, everything comes back to normal. 

What To Do: There is only one way to check the ignition coil: by replacing the old one, because a punctured coil is not going to give any signs with a multimeter

Faulty Fuel Pump:

If you think logically, the car may turn off due to a lack of gasoline in the fuel system.

Feeding gasoline to the injector or carburetor is arranged as follows: a fuel pump is installed in the gas tank, which is located at the very end of the car, which pumps gasoline from the tank and delivers it to the engine.

If it will work with interruptions, at certain moments the fuel will not flow into the combustion chamber of the engine.

In some cases, the fuel may not come in sufficient quantity and the car may well be dying on the move and then starting again. 

Replacing the fuel pump is easy and you can even do it yourself. In modern cars, it is under the back seat.

The price of this device is also small, around 26$, However, it depends on the specific model.

It is worth noting that there is another reason that disrupts the pump. We’re talking about boiling gasoline.

This phenomenon can be observed at high temperatures outside or while standing in a traffic jam, when there is no natural air blowing of the motor and gas tank with oncoming air.

Often turning the motor off for a period of time to cool down solves this problem.

Some car owners claim that the problem of gasoline boiling can be solved by directing the warm airflow into the cab.

Then the heat from the engine flows into the passenger compartment.

What To Do: Perform a repair, or even better, completely replace it.

Dirty Fuel Filter:

Another reason could be the fuel filter.

If it is not changed in time, it accumulates too much dirt, and then the gasoline supply slows down.

Of course, at low speed and not very active fuel injection, the car will move, but once you add gas, the engine starts dying because the gasoline just can’t get through the filter. 

What To Do: You should replace the filter. It is easy to do so since it is an expendable material and costs a penny.

Dirty Air Filter:

Like the fuel filter, the filter in the air purifier system is designed to trap dust, dirt and other foreign matter particles to prevent them from entering the intake manifold and combustion chamber where they can damage the cylinders.

Over time, the paper element in the filter gets clogged and blocks the correct airflow into the engine.

This will cause the engine to start running at idling speed and will stall or shut down when acceleration is attempted.

What To Do: If you have not replaced the air filter in over two years, replace it.

Most car manufacturers recommend that you change the filter every year.

Electrical failure

The problem of the car suddenly turning off can indicate a malfunction of electrical equipment.

In particular, oxidation may occur at the battery terminals. Consequently, the contact deteriorates as the resistance increases, which causes the engine to stall.

The battery itself may also fail. In the same case, if the generator does not produce the necessary current, the entire electrical network of the car is switched to power from the battery.

If you do not immediately see a light that indicates that there is no charging, the car will continue to move.

Taking into account that the light will be turned on and the ignition system is working, after a while, the battery will completely discharge and the engine will stop.

What To Do: You will have to charge/replace the battery and repair the generator.

Read More: How To Tell If a Car Battery Is Bad

Bad Fuel Quality

Do not forget that the quality of the fuel being refuelled can have a direct impact on the engine operation.

Some cars and some engines are generally forbidden to “feed” certain types of fuel. Therefore, watch and remember what we pour into the tank.

What To Do: Drain the gasoline from the tank and replace the fuel filter if the car has already started to stall due to fuel.

After that, try to fill only the right fuel of the proper quality level.

Crankshaft sensor malfunction

It is responsible for the overall timing of the ignition, both in gasoline and diesel engines.

If the sensor is faulty, then in 95% of cases the car does not start at all. But if the sensor is on the verge of working properly, the engine may fail.

The sensor is usually electromagnetic. It represents an inductor coil wound with extremely thin wire on a magnetic core.

In the process of operation, wear and tear it can get wet. If the engine is heated while driving, the sensor coils may open and the engine stalls.

Then, while you are trying to start it, the engine cools down, the sensor coils close again, and the car starts as if it should.

A typical situation of a faulty crankshaft sensor: the engine starts cold without problems, after 15 minutes of movement suddenly stalls, then, after you wander around the car for half an hour, it starts again without problems.

What To Do: If your somewhat far away from home, then replacing it isn’t really an option, so you can try to cool it down with a wet cloth or anything that’s cold, you’ll hopefully get home before it heats up again

Clogged Exhaust Pipe:

The engine may also stall if there is a malfunction in the pipes that are responsible for removing gases.

At full speed, the car will quickly “choke”, and pressing the gas pedal will completely stop the engine.

Malfunctions in the exhaust pipe system in 90% of cases are caused by contamination and clogged muffler. However, the catalyst converter may also fail.

What To Do: Carefully clean the silencer and remove foreign objects from it.

If there are problems with the catalyst converter, perform a full diagnostics of the exhaust system and replace this element.

Scenarios:

These are the answers to scenarios that can happen if your car suddenly turned off, and how to fix it.

If the engine stalled while driving in heavy rain

This may result in water falling inside the engine and settling on the elements of the ignition system.

The solution to this problem may be to remove moisture. You can also just sit in the car for a while without opening the hood, and then try to start the stalled engine

Read more: Can You Jumpstart a Car In The Rain? 

If the engine stalled after driving through a deep puddle

In this case, a “water hammer” may have caused the engine to stop.

This is when water through the air intake enters the intake manifold and then into the engine, which leads to the failure of the piston group and valves.

After the “water hammer”, the engine needs to be overhauled. Therefore, the driver must carefully overcome puddles, and it is better, if possible, to avoid them.

If the engine stalls while going uphill.

This can happen if there is very little fuel in the tank. With a long climb, the tank tilts, and some of the gasoline is concentrated in one place, far from the fuel intake, and while the fuel system will be present, the car will go, but after a while, due to the lack of fuel supply, the engine will stall.

If the engine stalls at idle

If a cold engine stalls after starting or its operation is unstable, first check the spark plugs and high-voltage wires.

Because insufficient spark formation or its absence on the electrodes of the spark plugs can significantly disrupt the operation of the power unit and as a result, the engine stalls at idle.

The solution is to check and, if necessary, replace damaged parts.

Steps to take if your car died on the road.

The safety of both yourself and other drivers will be your top priority. Here’s what to do if your car dies while driving:

1. Pullover to the side of the road

Try to slowly pull over to the side, if you find it difficult too difficult to slow down then use the emergency brake and proceed to a safe area.

2. Try To Restart The Car

Even if your car was able to start back up it doesn’t dismiss the fact that there’s something wrong with it, so its better to get to the mechanic shop asap.

3. Turn on your emergency flashers

Since safety is very important, this is done so that others will know that there’s something wrong and will give you space, or at least be aware.

4. Call for help

Call for a tow truck or someone you know to pick up your broken car.

Conclusion

As you can see, there can be many reasons for stopping the engine when driving. The driver, as a doctor, must take into account and analyze all the “symptoms” in order to establish an accurate “diagnosis” of the car. If the diagnosis is unclear, and you don’t have repair experience, you should contact specialists.