You should never hear your car, truck, or SUV’s engine knock. If you do, it could be something minor (hopefully) or a sign of impending doom. Kauai Auto Repair can figure out why your engine is knocking through both visual and diagnostic inspections. Once we’ve isolated the problem, we’ll fix it for you. Here are the top reasons why engines knock, one of which can be fixed with a simple gas change.
The Simple Gas Change
Your vehicle’s engine will knock if you put an 87-octane gas in a car that needs an 89 or 91. Fuel mixes with air to detonate in each cylinder. This action is a single detonation. Low-octane fuel does not burn as uniformly as higher octane does, and this can cause multiple, premature detonations in each cylinder. The detonations are basically tiny fireballs that crash into each other and make the knocking sound.
Bad Timing Also Affects Detonation
Engine timing can also cause detonation knock. The sparks plugs are what ignite the air/fuel mixture in the cylinders and they are set up to fire in a specific sequence. The plugs are controlled by the ECU or engine control unit in modern cars. If it is malfunctioning, it might signal the plugs to fire out of order, which can cause the detonation knock discussed above. Worn plugs can also cause this problem.
Too Much Air in the Engine
As you can imagine, your vehicle’s engine needs the air/fuel mixture to be just right in order to run efficiently. When the mixture has too much air in it, this is called a “lean” air/fuel mixture, and it can make your engine knock. Low fuel in the cylinders slows down the burning process, and this creates the perfect condition for multiple detonations. Finding the problem behind the lack of air can fix it.
Malfunctioning Knock Sensor
Engine knock can be a sign of serious trouble that will put you on the road to total engine failure. As such, your automobile is equipped with an engine knock sensor. The sensor detects conditions that can cause engine knock and, if it can, corrects those problems automatically. If the sensor itself is the problem, your engine might knock because nothing is being done to correct a minor issue.
Worn Rod Bearings
Finally, the pistons move up and down to turn the crankshaft which powers the wheels. This is a basic explanation of how your automobile moves, but it’s also what can cause a very bad engine knock. Rod bearings keep the piston movement smooth so they don’t bang against the crankshaft each time they go up and down. If the rod bearings wear down or break, the pistons knock against the crankshaft walls.
This is not only an expensive repair because of where the pistons and crankshaft are located but also because the pistons can damage the crankshaft wall. Call Kauai Auto Repair, LLC, right away if your engine is knocking just in case it’s the pistons. We are a full-service auto repair shop in Lihue, HI.