Can a Four-Cylinder Engine Run with One Cylinder Missing?

A four-cylinder engine cannot run with one cylinder missing. Engine misfire refers to insufficient power caused by engine failure. When one or more cylinders are not working, the engine's oil change interval may shorten, and issues such as sudden stalling, excessive fuel consumption, black smoke emission, and lack of power may occur.

If one of the four cylinders has insufficient compression, the engine may still start. If the compression loss is minor, the starting process may be difficult. However, if the situation is severe, the engine will fail to start entirely.

Causes of insufficient engine cylinder compression:

1. Excessive wear of the cylinder or piston rings, misalignment, sticking, or breakage of piston rings, leading to insufficient cylinder pressure. Prolonged exposure to high temperatures can reduce the elasticity of piston rings, preventing proper sealing and resulting in low compression.
2. Damage or poor sealing of the cylinder head gasket, causing insufficient cylinder pressure. The cylinder head gasket isolates adjacent cylinders, and if damaged, it can allow gas leakage between cylinders, reducing pressure in both.
3. Warping of the cylinder head's lower surface, leading to insufficient compression. High coolant temperatures can deform the cylinder head, compromising its flatness and sealing, which manifests as low compression during measurement. This is the most common cause of low cylinder pressure.
4. Improper sealing of intake or exhaust valves, resulting in insufficient compression. Valve cone erosion, bent or broken valves, or incorrect clearance adjustments can all lead to poor sealing and low cylinder pressure.

How to diagnose insufficient engine cylinder compression:

1. Unstable engine operation due to pressure loss, accompanied by popping sounds from the exhaust pipe and incomplete fuel combustion.
2. Difficulty starting the engine when cold. If the engine can be manually cranked past the compression stroke's top dead center without decompression, it may indicate low cylinder pressure.
3. Increased fuel consumption, with the oil filler port emitting exhaust gases or even spraying oil, which are signs of low compression.
4. Water droplets exiting the exhaust pipe, carburetor backfiring, and water leakage in or out of the crankcase may suggest insufficient cylinder pressure.

A four-cylinder engine can technically run with one cylinder missing, but it will operate poorly and may cause long-term damage. When a cylinder fails, the engine becomes unbalanced, leading to rough idling, reduced power, and increased vibration. Modern engines with electronic control units (ECUs) may detect the misfire and trigger a warning light, but older engines might continue running with noticeable performance issues.

Key problems include:

1. Reduced Power: The engine loses roughly 25% of its output, making acceleration sluggish.
2. Increased Fuel Consumption: The ECU may inject excess fuel into the faulty cylinder, wasting petrol.
3. Catalytic Converter Damage: Unburned fuel can overheat the exhaust system, leading to costly repairs.

If you suspect a misfire, diagnose it promptly. Common causes are faulty spark plugs, ignition coils, or fuel injectors. For example, a Ford Focus with a misfiring cylinder may exhibit jerking under acceleration. While short-term driving is possible, prolonged use risks severe engine damage.

From a mechanic’s perspective, running a four-cylinder engine with a dead cylinder is like limping on a sprained ankle. It’ll move, but poorly. The remaining cylinders compensate, causing uneven wear. Symptoms include a shaky steering wheel, louder exhaust notes, and a drop in MPG. Fix it fast—ignoring it risks warping valves or cracking the head gasket.