What is Engine Knocking?

An engine knock is a sign that something is wrong with your vehicle. It sounds like a hard clunk or ping, a sound that you might think indicates that two parts of the engine are hitting one another. Usually, an engine knock is a problem with the ignition of the vehicle. All gas-powered vehicles create combustion. For that, the spark plug needs to create a spark that detonates the gas and makes the engine work. Detonation is important, but an engine knock can be a sign that something has gone wrong with the ignition process. There are several things that you can look into to try to fix your engine knock.

Low Octane Fuel

Poor quality gasoline has a lower octane, which means it cannot tolerate as much pressure as other, higher-quality fuels. In some vehicles, this may not be a problem, but higher quality vehicles and European autos may respond very poorly to low octane fuel. The gas is supposed to resist combustion for a certain period of time, but it sets off early, which causes problems for the vehicle and can cause engine knocking.

You should find out whether your vehicle runs on normal octane fuel of 87, a mid-range of 88-90, or a premium of 91-94 and then ensuring that you’re putting the right kind in your vehicle.

Carbon Build-Up

Another issue that can cause engine knocking is carbon build-up. It may be related to poor fuel quality issues, or it may be the result of vehicle wear. If your vehicle is relatively new, then carbon build-up is most likely from fuel issues. Either way, the build-up puts pressure in the combustion chamber and changes when the gasoline lights up, which is then going to cause the engine knocking.

Thankfully, this issue can be simple to fix with cleaners, although it sometimes does require upper intake cleaning at a shop instead.

Faulty Knock Sensor

Engine knocks are serious problems that modern vehicles are actually designed to sense and prevent. The Engine Control Module (ECM) is capable of sensing knocks and other fuel problems and making adjustments to avoid them. However, if the knock sensor in the ECM isn’t working, then it may not know a knock is happening and may therefore not compensate. While this problem sometimes turns the check engine light on, it doesn’t always happen.

Combustion Temperatures 

An overheating engine is bound to cause other problems. If your combustion temperature is too high, then you may get an engine knock. And, overheating isn’t the only thing that can raise combustion temperatures. A combination of issues such as wrong spark plugs, carbon build-up and other issues can all combine to raise temperatures and make conditions for your vehicle’s ignition less than ideal.

Wrong Spark Plugs

The manufacturer or an auto shop may have put the wrong spark plug into your vehicle. This is a rare but serious problem that can cause serious damage to your vehicle. There are many different kinds of spark plugs and the wrong one can cause the gasoline to light early. Just as with the other causes, early gas ignition will harm your vehicle and make an engine knock sound. While the owner’s manual should have information on what spark plug your vehicle is supposed to have, or a technician can tell you.


Ignition Timing

An over advance ignition timing is when the vehicle tries to fire the spark plug too soon, causing ignition early. There are many different components of the timing system which may be the cause of this pre-ignition. Timing belts and distributors are likely culprits. If one or more has failed, that will explain your issue.

Some select vehicles actually have adjustable timing, and if so, it may be that the timing just needs to be readjusted in order to line up with the rest of the vehicle.

Lean Air/Fuel Mixture

The air/fuel mixture is the last suspect of an engine knock. Many components might let too much air into the fuel mixture, creating early combustion. It’s possible that your vacuum line has been knocked off, the fuel pump tank has weakened or the intake gaskets may be leaking.

Get Engine Knocks Resolved

When your vehicle isn’t’ starting up properly and has an engine knock, more and more damage is slowly being dealt to the parts involved. Some of the causes can do damage to the engine quite quickly, so it is important to always get an engine knock looked at right away.

Schedule your appointment at one of our three locations today! Contact us online here.



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