Why Does an Engine Stall?

engine stalled on a road

What causes an engine to stall at idle?

Is there anything more nerve raking and worrisome than your car engine stall at the intersection, or in the fast food line?  What is stalling? When a person is stalling, it is usually because we are procrastinating doing something, like washing dishes or filing taxes. When a car engine stalls, this means the car has died. It means you’re not going anywhere until you get it started again. A car engine stall can happen even while you’re going down the road! 

Today, we’re going to answer some questions about Why would an engine stall and what to do when that happen.  Often an engine stall isn’t any major problem, but it could be.  If you know a few things about what causes for a stalled engine, it won’t be as scary if it does happen to you. 

No matter what kind of car you drive, every engine needs 3 key things to operate with a smooth idle:

  • Good air to fuel ratio
  • Sufficient idle speed
  • A strong spark

If a car is lacking any one of these three things, it will stall at an idle. There could be any number of things that cause these three important things not to be working properly.  Some possibilities are the idle air bypass motor, or the idle speed control motor is bad. When these two devices aren’t providing the right idle speed, it can cause the engine to die. Another device that can cause an engine stall is the PCM.

The PCM is the power-train control module, which is a control unit. It works with two other devices: ECU (engine control unit) and the TCU (transmission control unit). If any of these three are working in conjunction with each other, it can cause an engine stall.

What causes rough idle and stalling?

There can several reasons why a car engine is idling rough. Those reasons could be something minor or major, if the engine stalls while idling rough, it could be a bigger problem. In either situation, it isn’t just something annoying and inconvenient and the car should be inspected by a professional mechanic.   Some of the most common reasons for a rough idling and engine stall are: 

  • Fuel Injectors: The fuel injectors could be dirty and not mixing the air and fuel right, cutting back on the amount of fuel is getting to the engine. 
  • Idle Speed:  The idle speed on a car is typically between 600 to 1,000 RPMs. A car that has a rough idle may be the speed setting is incorrect. A professional mechanic can reset this for you. 
  • Vacuum System: Every car has a vacuum system and if it develops a leak, the computer isn’t able to regulate the ratio of the air and fuel mixture, leading to a rough idle and possible engine stall. 
  • Spark Plugs: Spark plugs create the spark that allows a car’s engine to bur the fuel. When they are damaged or have been installed improperly, it can case the car to idle rough.  
  • Fuel Pump: Fuel delivery problems can cause a rough idling car. If the fuel pump is clogged or about to go out, it can’t get the fuel where it needs to be. The car will idle rough and the engine stalls. 
  • Fuel Filter:  Just like the fuel pump, if the fuel filter becomes clogged, it will cause a rough idle and engine stall too.
  • Electrical Components: A car has several electrical components and if any of them fail or are having problems, you can get a rough idle or the engine stalls. The electrical components include the spark plugs, plug wires, coil, or the ignition module.  
  • Airflow Sensor: If the airflow sensor goes bad, it can cause a rough idle because the engine can’t get the right amount of air the computer is telling it needs. This can also lead to an engine stall.
  • Oxygen Sensor:  The oxygen sensor measures if the gas is lean or rich and tells the computer ow to adjust the ratio to the air. When oxygen sensor is bad or dirty, it isn’t sending the right signal to the computer and causes the car to idle roughly and can cause the engine stall.

Why does my car stall when I stop?

An engine stall while a car is stopped could be the air to fuel ration, the fuel not pumping, or something electronic. A common reason why this happens is because there isn’t enough fuel getting to the engine to keep it running while stopped. What should I do if my engine stalls?

burst engine smoking

Is stalling bad for the engine?

Manual shift cars are known more for experiencing an engine stall, but automatic shift cars will stall too.  In the case of a manual shift car, it is usually because you didn’t engage the clutch. Simply restart your car and you’ll be on your way in most cases.  In the case of an automatic shift car, you’ll notice the engine stall when your power steering quits, then the power brakes won’t work. At this point, do your best to coast to a safe place off the road, turn on the hazard flashers and try to restart the engine. If it won’t start, call for help. 

Should you have any of these issues of engine stalling with your car, keep your safety in mind first.  Then get your car to a professional mechanic that will know how to fix a stalled engine. The sooner the better because while it may be a small issue know, ignoring it could allow that small issue turn into something bigger and more expensive. Call 847-895-9131 today for your engine repair needs in Schaumburg, IL.