What causes a dead cylinder and how to fix it?

The internal combustion engine is made up of many parts that ensure its proper functioning, but various defects can occur that can weaken its power and can even lead to total failure.

One of these problems can be a cylinder, or more, that no longer works at all, and because of this, the driver will feel a significant engine power loss.

The most common causes why a cylinder is dead or misfiring is due to:

  • Lack of spark,
  • Low compression,
  • Bad ignition coils,
  • A rich air-fuel mixture,
  • Bad timing.

We will discuss further details later.

If we take as an example a 4-cylinder engine, the combustion will occur only in three cylinders making the engine lose a quarter of its power.

Going further, if two cylinders are not working, the engine’s power will be reduced by 50% and if three cylinders are not working, then the car will not start at all, but I have seen cases when the engine ran with only one cylinder :).

Symptoms of a dead cylinder

  • The engine loses power. 
  • Increased fuel consumption. The engine will struggle more to function, and this will be an adverse effect.
  • Increased vibration. If one cylinder is not working, you will notice these vibrations.
  • Uneven exhaust.

Causes of a dead cylinder

1. No spark

One of the most common causes. If there is a spark in other cylinders, the wire to this cylinder is shorted. You can install a spare and check the spark on this particular wire. Other reasons may be a damaged spark plug, or one ignition distributor contact may be broken.

If your car uses a dual or quadruple ignition coil, one of the windings may be faulty, you can check the winding with a tester. Also, in the injection system, there may be a failure in the ignition pulse shaping of the control system.

2. Low or no compression

Low compression indicates damaged or stuck compression rings. These rings are installed in the piston grooves. Due to their elasticity, they fit tightly against the cylinder walls, but a ring can break.

The compression is measured with a peak pressure gauge. You can install it in the spark plug’s place and start the engine. It will show the maximum pressure that was in the cylinder while the engine was turning.

Another reason is if low-quality oil is used in the engine, deposits, carbon build-ups, and other debris will begin to accumulate in the grooves in which the rings are installed.

This causes the ring to jam and stops springing and sticking tightly to the cylinder walls. You can use cleaning additives in the oil, butut the probability of success is low.

If the rings are stuck and do not come out after using the additives, then you need to remove the engine to clean and replace the rings, which is a costly operation.

It is not necessary to bore the cylinders when replacing the rings. However, the only way to find out if drilling is required is to disassemble it, and it is used to remove irregularities and faults on the cylinder walls.

If the walls are smooth, and there are no deep grooves and furrows on them, it is not necessary to bore them, but otherwise, you will need to drill them.

3. Bad timing

If the camshaft is incorrectly aligned relative to the crankshaft, this is the cause of a dead cylinder The moment of opening and closing of the intake and exhaust valves will not coincide with the engine stroke.

For example, at the piston’s TDC the valve may be closed, so the flash will occur not only in the cylinder but in the intake or exhaust manifold, depending on which valve is not closed.

This can be due to a stretched timing drive. As it operates, the chain or belt will stretch out, therefore, the opening or closing angles can shift, causing the engine to stall.

4. Bad injectors

A failing injector could be the cause of a dead cylinder. It may be over-injecting, not injecting gasoline into the intake manifold, or directly into the combustion chamber. You can check the performance of the injectors on the test bench.

5. Alternator malfunction

Power surges when the engine is running can cause unstable operation of the ignition coils, fuel pump, and so on. This can be seen at night, the headlights may flicker.

On the other hand, if the battery is in good condition, it should compensate for these losses. Headlights can dim when the engine has an unstable operation at idle. And it can be a consequence of a dead cylinder.

6. Air leaks

If there is not enough air in the air-fuel mixture, the fuel will burn poorly, and one or more cylinders not function. The air that enters the intake manifold after the MAF sensor is considered to be unaccounted for. The ECU does not see it, so it does not take it into account when preparing the fuel mixture.

Can a dead cylinder be fixed?

Check the spark plugs

In order to fix this problem, we have to take separately all the reasons that cause a malfunctioning cylinder. So, we will start with the most common, spark plugs.

We unscrew one spark plug at a time and look at their insulator. If it’s covered with dense deposits, it’s hard for the spark to penetrate it. Inspect the external condition of the spark plug insulator. The causes of deposits on spark plugs can be many.

If there are micro-cracks, the spark will escape through these damages. You need to look at the inner insulator, which is screwed into the cylinder head, and the outer insulator, on which the armature wire cap is put on.

Check the high Voltage Wires

The wires can be a culprit. Because of the harsh operating conditions, they can get loose. Plus poor labor can cause them to have micro cracks.

The high discharge punctures them. In these places, a light stain with black dots or streaks of soot forms. It is best seen in the dark when the engine is running. You can observe sparks at the breakdown points.

The spark will be weak or absent altogether, causing the cylinder to stop working. You should replace the armored wires with new ones.

Check the ignition coils

Some vehicles may use an ignition module or individual coils for each spark plug. Their failure also leads to a dead cylinder. If the engine has an unstable operation, remove the cap from the spark plugs one by one. 

Observe if there is a spark between them. If there is sparking on all spark plugs, the ignition module is in good order.

How much does it cost to fix a dead cylinder?

To costs of fixing a dead cylinder will vary depending on the car make and model, but in general, costs are between 200$ and 350$ for the cylinder and another 150$ to 250$ for the labor.

Can you drive a car with a dead cylinder?

It is not advisable to drive a car with a dead cylinder. The corresponding injector should be unplugged in order to not damage the catalytic converter, but most cars will do that automatically if it detects a misfire in the cylinder.

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