Engine Knocking and What to Do About It

Gasoline or spark-ignition internal combustion engines usually have to deal with knocking. It's also known by the names of pinking, pinging, spark knock, or detonation.

It happens when combustion of your air/fuel mixture in your cylinder doesn't result in flame as ignited by your spark plug. The knock specifically occurs when the mixture explodes outside of the envelope of your engine's normal combustion front, resulting in a jolting effect on your motor.

Also, your engine is likelier to end up with knocks as the compression ratio increases. In comparison, a diesel engine doesn't have to deal with knocking at all. This is because it has bigger cylinders, which in turn provides more space for your diesel fuel to combust.

The Reasons Why Engines End Up Getting Knocks

  • When Do Knocks Occur on a Gasoline Engine? The charge from the fuel and air is supposed to be ignited by the spark plug alone. When it's ignited by something other than the spark and it is ignited somewhere other than the precise point in the piston stroke or the peak of the combustion process, that's when knocking or pinging occurs. Every time combustion occurs besides that optimum moment for the four-stroke cycle, your engine will be rattled and you'll hear that sound. Naturally, this results in wasted mileage and a slowly worn down engine.
  • Why Does an Engine End Up Getting Knocks? The pinging sound make when there are knocks are created by the shock wave from the detonation, resulting in a dramatic increase in the cylinder pressure. Some knocks are inconsequential but if they become big enough or occur often enough, they can destroy your engine. The reasons why these knocks happen in the first place includes ignition delay within the injectors, increased engine temperature, or fuel injector failure to completely ignite the fuel, among many other reasons.
  • How Can You Avoid Knocks In Your Engine? To avoid engine knocking, you can also go get a diesel engine with maximum compression ratio instead or fix the underlying problem behind the knocking. The reasons as to why your engine is knocking should be fixed in order to stop it. Some are easy to fix while others are more serious and can therefore result in severe engine destruction. It depends on how strong the knocking or detonation is. As a rule of thumb, it's mostly the air/fuel mixture's fault or your spark plug's fault.
  • How Should You Troubleshoot Engine Knocks? You can prevent this detonation by using a fuel with a high-octane rating. This increases the fuel's combustion temperature and decreases detonation proclivity. You can also enrich the air/fuel ratio to alter combustion chemical reactions, thus reducing the combustion temperature and raising the margin above detonation. You can also reduce the ignition timing, reduce the engine load, reduce peak cylinder pressure, or decrease the manifold pressure by reducing the boost pressure or throttle opening.

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