Stall (engine)

For the effects of a stall of the airfoil within the compressor of a jet engine, see Compressor stall.

A stall of an engine refers to a sudden stopping of the engine turning, usually brought about accidentally.

It is commonly applied to the phenomenon whereby an engine abruptly ceases operating and stops turning. It might be due to not getting enough air, fuel, or electric spark, mechanical failure, or in response to a sudden increase in engine load. This increase in engine load is common with manual transmission in cars when the clutch is released too suddenly.

The ways in which a car can stall is usually down to the driver, especially on manual transmission. For instance if a driver engages the clutch too quickly while stationary then the engine will stall; engaging the clutch slowly will stop this from happening. Stalling also happens when the driver forgets to depress the clutch and/or change to neutral while coming to a stop. Stalling can be dangerous, especially in heavy traffic.

A car fitted with an automatic transmission could also have its engine stalled when the vehicle is travelling in the opposite direction to the selected gear. For example, if the selector is in the 'D' position and the car is moving backwards, (on a steep enough hill to overcome the torque from the torque converter) the engine will stall. This is because, hypothetically, if the car is rolling backward fast enough, the force from the rotating wheels will be transmitted backward through the transmission and act as a sudden load on the engine.

Digital electronic fuel injection and ECU ignition systems have greatly reduced stalling in modern engines.

See also

• Stall torque