It’s never a good thing if you hear knocking coming from your engine. Mike’s Auto Service & Repair advises that most knocking is caused by a detonation problem in the cylinders. The air and fuel in each cylinder should only fire once. If it fires multiple times, this is the knocking sound that you hear. Let’s talk about the reasons why engines knock below.
The Engine Timing Is Off
One thing that can cause multiple detonations in the cylinders is the engine timing. Specifically, the spark plugs are timed to fire in a specific order. They are controlled by the main computer chip, which is called the engine control unit. If the spark plugs are worn or the engine control unit is malfunctioning, the timing of the plugs may be off and you will hear your engine knock.
The Fuel Mixture Is Lean
Each cylinder needs the right amount of fuel to fire only one time. If there is more air than fuel in one or more of your vehicle’s cylinders, you will hear knocking sounds caused by multiple detonations. When there is more air than fuel in the cylinders, you have what is called a lean fuel mixture. This can be caused by a fuel delivery problem or a faulty oxygen or mass airflow sensor.
The Fuel Octane Is Too Low
Always put the recommended octane in your fuel tank. If your vehicle requires octane that is higher than 87 yet you put 87 in the tank, the fuel will not fire fast enough and you will end up with multiple detonations. Again, these detonations are what are creating the knocking sounds that you hear. Check your owner’s manual to see the type of fuel and the octane recommended for your automobile.
The Knock Sensor Is Bad
A knocking engine is bad. As such, the engine has a knock sensor to alert the engine control unit when the conditions are just right to create an engine knock. This sensor can go bad, and if it does, you may end up hearing knocking sounds coming from your engine because it has not been able to communicate with the engine control unit.
The Rod Bearings Are Worn
Finally, this cause of engine knock is a serious one. As you already know, the pistons go up and down inside the cylinders to help generate engine combustion. The rods attached to the pistons are moved by rod bearings. When these rod bearings wear down, the pistons crash against the cylinder walls.
Mike’s Auto Service & Repair in West Springfield, MA, can help, so give us a call today. We will find out why your engine is knocking.
