With the exception of worn rod bearings, most engine knocks are caused by faulty detonation. Ideally, the air and fuel in each cylinder should only detonate one time once the spark plug issues a spark. There are a number of things that can cause the air and fuel to detonate multiple times. When this happens, you end up with little fireballs in your cylinders that crash together. This is the knocking that you hear. Prepare Auto Repair explains more below.
Bad Spark Timing
Your spark plug timing may be off because the plugs are old and worn or because the engine control module is malfunctioning. The engine control module is your vehicle’s main computer chip, and it tells the spark plugs when to fire. If they are not firing at the correct time, you may end up with a knocking engine. Again, this is due to the multiple detonations in the engine’s cylinders.
Faulty Knock Sensor
Your automobile is equipped with a knock sensor. This sensor lets the engine control module know if the engine is knocking. The engine control module then makes adjustments to stop the engine knock if it can. If the knock sensor is going bad, it may not alert the engine control module to the engine knock. Consequently, you will hear your engine knock until you have the knock sensor replaced.
Lean Fuel Mixture
Another thing that can cause multiple detonations in the cylinders is a lean fuel mixture. This mixture is heavy with air and has very little fuel in it. Consequently, the excess air can create the little fireballs we discussed in the introduction to this blog post. As such, your engine will knock until such time as the engine control module corrects the problem if it can.
Low Octane Fuel
If you drive a high-performance automobile yet put low octane fuel in it, you will end up with engine knocking. The low octane fuel is unable to fire as quickly as your engine needs it to. As a result, you end up with multiple detonations in the cylinders and engine knock.
Worn Rod Bearings
Finally, the pistons are attached to rods that move up and down to move the pistons up and down in the cylinders. If the rod bearings are wearing out, the rods will wiggle as they move the pistons up and down. Consequently, this will cause the pistons to crash against the cylinder walls. This could be the loud knocking that you hear coming from your engine.
Call Premier Auto Repair in Tyler, TX, today if your engine is knocking. We can get to the bottom of the problem and fix it.