There are two main reasons your vehicle may begin stalling: insufficient fuel or too much air. However, narrowing down the culprits causing either of these two things requires a bit of investigative work. With that in mind, this article will provide a short list of seven factors that can potentially contribute to a stalling problem. If your car’s engine suddenly dies – either right after starting or while on the road – one of the following reasons is likely to blame.
Coolant Sensor Is Malfunctioning
Your car’s powertrain control module (PCM) regulates the amount of fuel delivered to the engine. It relies partly upon the coolant sensor to determine the right amount. If the sensor is malfunctioning and sends the wrong signal, the PCM will make the air-fuel mixture too rich or too lean.
For example, if the sensor tells the PCM that the engine is too cold, the computer will send too much fuel to the combustion chambers. If the sensor says the engine is too hot, the computer will lean out the mixture, causing stalling.
Spark Plugs Are Fouled
When a cylinder’s spark plug becomes corroded or worn down, it becomes less capable of generating a reliable spark. That creates a misfire. If your car is idling, the misfire can cause a stall. This usually occurs when people neglect to replace their plugs before they become fouled.
Excessive Load On The Charging System
Few people recognize their vehicle’s charging system as a possible factor in causing a stall. If your battery is severely depleted, your car’s alternator might be forced to work harder. That, in turn, can place a greater load throughout the charging system and on your engine. If this results in a low idle, your vehicle might stall while you’re stopped at a traffic light.
Contaminated Gasoline
Thankfully, this happens rarely. There have been situations during which a gas station’s fuel inventory somehow becomes contaminated with water. Gasoline is specifically formulated to burn efficiently during the internal combustion process. If it becomes contaminated by any substance (including, but not limited to, water), it might not burn in the combustion chamber. That can cause stalling.
Vacuum Leaks In The Engine
Vacuum leaks can cause a number of problems, including a fast or rough idle, misfiring when you accelerate, and of course, stalling. The leaks normally develop in hoses that deteriorate over tens of thousands of miles. They can also form near the intake manifold gasket and exhaust gas recirculation (EGR) valve.
Bad Airflow Sensor
Your car’s mass airflow sensor measures the amount of incoming air by using an electrical current. This component can slowly become contaminated with debris and dirt. This hampers its ability to accurately measure airflow, which can influence the air-fuel mixture that ends up in the combustion chambers. As mentioned earlier, if the mixture is too lean, your vehicle might stall.
Engine Compression Leaks
Your engine’s combustion chambers need sufficient compression in order to ignite the air-fuel mixture with enough force to operate effectively. If there are leaks, the lack of sufficient compression can cause stalling. This occurs when the intake or exhaust valves become less able to close securely, or the pistons inside the chambers become worn. Unfortunately, resolving either problem is usually expensive.
A stalling engine is always inconvenient, and often costly to fix. The first step is to diagnose the root cause. Unless you have access to the necessary tools, this is best left to a trained mechanic. Once the offending component (assuming it’s not a hose or bad gas) has been identified, it usually needs to be replaced.