What to do when suddenly your engine stalls while driving? Well, this kind of incident can come from either a modern car or to an old sleeper car. Why? Because there are so many things to consider why this issue occurs.
Car shutting down while you are on the highway is one of the worst thing to experience as it can give you confusion and panic at the same time.
So, what could be the reasons behind this issue? In this blog post, I will tell you some of the common and not so usual reasons (in detail) why some cars suddenly shuts off while in motion. And of course, I’ll give you possible fixes on how to solve this automobile issue.
Read on and find out more!
Why Does My Engine Stalls All of a Sudden While Driving?
Stalling engine especially while driving isn’t just frustrating but also puts you a lot closer in danger.
So to be able to understand why your car behaves differently, you need to know how the engine works – combustion process, ignition system, sensors, air intake, fuel system, and other small things that can affect engine stalling.
All these components contributes to your engine’s combustion process, which helps keep your motor working smoothly. One error or issue from these system can bring your engine to a halt hence lead to stalling.
So let me break the causes of this particular issue in groups so you’ll have better understanding how engine works and why they shuts off unintentionally.
Fuel System Issues
One of the most common causes of engine stalling (or why engines won’t start) while you’re driving is faulty issues within the fuel system.
This can come from a simple dirty fuel filter, to a more complex issues like faulty SCV, injectors, sensors, pump and much more.
So lets see some of the possible reasons of car shutting down randomly due to a bad fuel system.
Your Run Out of Fuel
I can’t stress this enough. Combustion inside an engine requires fuel to run alongside air, without fuel in your gas tank, then your motor will of course shut down.
This is possible when your fuel gauge is faulty and provides erroneous output that gives you wrong idea about the status of your fuel level in the gas tank. If you can’t track the actual amount of your fuel, stalling is just around the corner.
To fix this, you need to replace the bad fuel gauge or the sensor inside your fuel tank.
Bad Fuel Pump
One best causes of car stalling is bad fuel pump. As its name suggest, it pumps fuel directly to your engine to create successful ignition and combustion, which keeps the motor running.
The fuel pump is initiated when you turn the key on as it give signals to the ECU. There is an automated or electronic way of how fuel is being pumped into the engine, and there is also a manual pump that is mostly located inside the engine bay.
Why you start the engine, the fuel pump creates pressure to help push fuel pass in the fuel lines into the injectors. If your fuel pump doesn’t have enough pressure to do this task, fuel injectors won’t receive proper amount of fuel and will inevitable lead to stalling.
To fix this, you need to diagnose, repair or replace your car’s fuel pump. Otherwise, all other components in your fuel system will also fail.
Dirty Fuel Filter
Fuel filter’s job is to “filter” any impurities, contaminants and other foreign objects inside the fuel lines before it reaches your injectors.
This means that your car’s fuel filter gets dirty and clogged overtime, which needs replacement. If you neglect this simple maintenance job, then it will block the fuel lines and not enough fuel will pass through your injectors leading to stalling.
As said above, the simple fix for this is just replacing the fuel filter. However, if your car already shuts down due to bad fuel filter, chances are your injectors and other fuel system components are already damaged. So you better replace your filter according to its maintenance schedule.
Faulty Fuel Injectors
As mentioned above, fuel system can leak and get clogged if not maintained properly and correctly. And most of the time, fuel injectors goes bad whenever some contaminants reached them and are not filtered by the fuel filter.
There are many other reasons why injectors are going bad, but I am not going to state them here as this would make the post longer than usual.
How to tell if one of your motor’s injectors are bad? One way is the check engine light is on, and the other way is to manually remove each injectors and do diagnostic tests.
There’s a high chance that an injector can be repaired or they just require cleaning. But diesel fuel injectors are quite complex and may need replacement.
In other cases especially if your car has high mileage, you only need to relearn the injectors so that it would function more efficient again.
Bad Suction Control Valve
A suction control valve is a component found in common rail engines to help control fuel pressure which allows only the required amount of fuel to be pumped through the engine. And yes, it is designed for diesels only.
I personally experienced this myself when my previously owned Toyota diesel MPV suddenly stalls randomly while driving. The mechanic tried everything in the book to pinpoint the cause of why the engine stalls during 2nd and third gear.
Of course he found the culprit and it was the SCV. Thankfully, I don’t need to replace the SCV but only needs cleaning. So make sure that your diesel engine gets properly maintained especially the fuel system so you’ll avoid any engine mishaps on the road.
Air Intake System Issues
Next area that we are going to look at is the air intake system. As I’ve mentioned above, insufficient air is one of the reasons why engine stalls. So you have to know the basics of this system to better understand why your car motor needs adequate amount of air to run.
Air intake system is composed of your air intake filter (where air is sucked into the engine), mass air flow sensor, turbocharger/supercharger and intercooler (if your engine is supercharged or turbocharged), throttle body and intake manifold.
To create combustion, your engine needs proper amounts of fuel and air. And insufficient amount of air will make your engine’s RPM run wild or weak, or in worse case scenario, your car will shut down.
So let me tell you some of the causes of engine stalling based on faulty or bad air intake system components.
Dirty Air Filter
Like any filter in your car, air filter or sometimes called air cleaner, helps filter debris and other things from entering and damaging your engine. Hence it is called “air cleaner” in the first place.
And most factory air filters are replaceable especially if they become dirty and clogged. Of course, a clogged air filter will inhibits clean air from entering your engine which will disrupt the combustion process, hence the reason why the engine stalls.
So as a car owner, you should not neglect to clean or replace a dirty air filter. Check your owner’s manual and see the correct mileage when to replace your air cleaner.
There are also some air filter available in the market that are designed to last a vehicle’s life time. These are commonly used for performance cars though they are now heavily marketed as an aftermarket upgrade options for car enthusiasts.
These air filters are reusable and only requires simple cleaning from time to time.
Bad or Dirty Throttle Body
Throttle body is responsible for supplying the right amount of air to your engine. It dictates the amount of power your engine needs to produce depending on how you depress your accelerator pedal.
This component is found between the intake manifold and the air intake MAF sensor. And within your throttle body, there is a TPS or throttle position sensor which gives signals to the ECU how much gas to give or take away.
If the car senses that there isn’t enough gas, then the TPS will shut off the engine to avoid any damage. This means that a faulty throttle body is one of the main reason why engine stalls while driving.
So better have your throttle body checked by a professional to fix the issue, or a replacement is also an option.
Dirty Intake Manifold
Intake manifold is the last component in air intake system where the air enters the engine. New vehicles do have clean intake manifold as less oil pass through it coming from the engine.
And blowby gasses coming out the combustion chamber are being recirculated back to the system to help reduce environmental pollutants. This is composed of air with fuel and oil, and they all pass through the air intake system.
Overtime, this blowby gasses will form carbon deposits and oil residues, which sits and sticks inside the intake manifold. This clogs the air flow and as you already know by now, insufficient air means poor combustion that leads to engine stalling.
To prevent your car shutting down due to clogged intake manifold, simply remove the manifold from the engine and clean it with kerosene or gasoline (best for removing carbon deposits).
Bad Turbocharger or Clogged Intercooler
For turbocharged engines, a bad or faulty turbocharger and dirty intercooler can cause your car to shut down without warning.
Turbochargers are used to help create additional power by generating immense pressure. A faulty turbocharger can either trigger overspinning or under spinning of its turbines which results to damage.
This disrupts the air that is being passed inside the engine. Insufficient engine due to a bad turbo leads to low power or stalling engine.
But what about intercoolers which only acts as an air cooling mechanism? As mentioned above, engines naturally produces blowby gasses and if your engine has turbocharger, these gasses with oil and fuel will fill up your entire intercooler, inhibiting proper air flow to the engine.
So aside from intake manifold cleaning, make it also a habit to clean your intercooler as well.
Faulty Ignition System
Another reason why your engine stalls while driving is ignition issues. And this vehicle system is the least talked about when dealing with stalling issues as many car owners don’t know much about them.
That’s funny because ignition system is the one responsible for turning on your car.
So let me cite some plausible stalling reasons for you based on faulty ignition system.
Bad Ignition Switch
Ignition switch is part of your car’s electrical system. It turns on or off almost all electrical components in your car (such as radio, lights, etc.) especially your engine ignition system.
A bad ignition switch will not just cause issues with engine stalling, but also for other car accessories such as airbag, door locks, headlights and many others.
To avoid damaging your ignition switch, avoid installing any aftermarket gadgets on your ignition switch such as turbo timers as it can cause issues especially if not installed correctly. If your ignition switch is bad, it is important to replace it immediately.
Faulty Alternator
Your alternator is the power plant of your car (yes not your battery okay) where the power is being stored in your battery. So besides of being that power source of your engine, it is also designed to keep your car’s battery charged all the time.
Of course, the more electrical components you have on your car, the more load you put on your alternator. This is the reason why some cars owners upgrade to higher amp alternator or even uses two alternators in their vehicles.
But if you have a bone stock alternator from the factory and you add more accessories such as subs, amplifiers and many others, it will draw more power from your alternator which will eventually drain your battery. This will inevitable lead to car stalling.
After years of car use, your alternator may eventually fail. There are also other reasons why alternator goes bad such as incorrect signals being thrown to the ECU by odometer control module (regulates how much power is drawn from the alternator).
To know if your alternator is bad, you can simply buy aftermarket alternator and battery diagnostic testers online, which easily tell if your alternator is faulty or not.
Faulty Spark Plug
For petrol engines, a good working spark plugs are a must to have successful ignition. Otherwise, you won’t be able to start your engine or worse, your car may shut down while in motion.
A spark plug is consist of a metal electrode that is surrounded by a ceramic insulator. To create a “spark” to help ignite the fuel within each cylinder, the electrode heats up and produces electrical current that travels through the wires to the distributor until it reaches each cylinders.
Overtime, spark plugs accumulates dirt and corrosion which lessens its capacity to create spark. You will need to clean them or replace them according to your car’s maintenance schedule.
Dead Battery
Another important component in your car that needs regular checking is you battery. If your battery is already 3 or 4 years old, then you can bet that it already has weak charge and replacement is imminent.
If your car engine stalls while driving due to bad battery, it isn’t always due to years of usage, but can also due to parasitic drain issues.
What are parasitic drain? It means that there is something in your car that is draining more power even if your engine is off. What causes these unnecessary power drain?
Well, it can come from stereo, dash cams, and many others. So in order to preserve your battery’s health and get the best investment out of it, ensure that your electrical system doesn’t have any parasitic issues.
Bad Ignition Coil
Ignition coil is an important component of your ignition system as it helps produce high voltage charge to ignite fuel inside your engine’s cylinders. They are located over the top of the spark plugs.
Some signs of a failing ignition coil is a misfire or engine shutting off while driving. So you know why ignition coil can be the culprit to your problem.
There are much work and a lot of effort are required to replace an ignition coil not to mention that it is quite pricey to have them tested. So I suggest that just replace them if your mechanic found the coil broken or if your ECU provides a check engine warning light.
Engine Stalls due to Malfunctioning Sensors
I already stated above some of the sensors in your vehicle that may play a big role in engine stalling issues. So I will cite them here as a group to keep this post short okay.
First sensor that needs to be checked is the crankshaft position sensor. It is an electronic device that monitors the position or rotational speed of the crankshaft. This sensor can intermittently fail, making it hard to diagnose. A bad crankshaft position sensor leads to stalling issues.
Another sensor that is important for keeping the engine running is the mass airflow sensor or MAF. It is used to help control how much air is being passed into the engine. If this sensor fails, it will cause your car to run erratically, gives unstable RPM and will lead to engine stalling.
Aside from a bad MAF sensor, a faulty manifold absolute pressure sensor or MAP, is another reason why engine stalls while driving. If measures the atmospheric pressure within the intake manifold. The engine management then use the data to calculate air flow and fuel injection.
A bad MAP will cause havoc to the entire air intake system which inevitable lead to your car shutting down.
Lastly, a bad engine control unit itself (ECU) can cause engine stalling. Once your ECU goes bad, it won’t follow the command or signals that are coming from each sensors of your car system. This include coolant temperature, oxygen temperature, air intake and many others. The result? Stalling of course!
Conclusion
Now you know the various causes of why your engine stalls while driving. To give you a quick summary, here are the things that you should do in order to avoid this car problem:
- Check your instrument gauge cluster and see if there are warning lights
- Always follow every maintenance schedule set by your car manufacturer
- Keep your air intake system, ignition system and fuel system clean and maintained
- Always check the health of your battery and alternator
The next time you experience engine stalling while on the road, you now know how to fix the problem yourself! Until next time!
