A knock sensor senses vibrations that occur during engine knock and allows the car's power train control module to reduce ignition timing to prevent knocking. The sensor is located on the engine block, cylinder head or intake manifold and is a piezoelectric material that creates a small charge when vibrated. Engine knock leads to engine damage and is caused primarily by poor fuel, deposits in engine or incorrect spark plugs.Know More
During normal combustion, the spark plug ignites the fuel mixture and the flame front progresses smoothly from the plug until the fuel mixture is completely burned. During engine knock, however, pockets of spontaneous explosions occur away from the spark plug, producing shock waves that rapidly increase cylinder pressure, causing interference to the engine cycle and catastrophic damage to the pistons and head gasket. Reducing the ignition timing causes the spark plug to fire later, reducing cylinder pressure and preventing knock.
Low-quality and low-octane fuels lead to high cylinder pressure and combustion chamber temperatures, causing fuel to ignite early. Higher-octane fuels burn more slowly and resist detonation due to extreme cylinder conditions. Deposits in the cylinder walls also raise cylinder pressure by taking up space normally used by the fuel mixture. Additionally, incorrect spark plugs may improperly burn the fuel mixture, causing deposits to form in the cylinders and increased operating temperatures.Learn more about Engine
Most knocks come from the ignition or the injector nailing. Fuel injectors can also cause a knocking noise, especially in older diesel vehicles.Full Answer >
An engine knock results from one of several problems such as a loose connecting-rod bearing, bad fuel mixture, worn spark plugs or carbon build up inside the cylinder walls. A vehicle experiencing a knock should be quickly inspected to avoid any serious damage to the internal components of the engine.Full Answer >
Typically located in the timing cover or directly inserted into the lateral portion of the main block of an engine, the crankshaft sensor establishes the ignition timing for a vehicle. It also determines engine speed.Full Answer >
The basic steps for replacing a crankshaft sensor include disconnecting the car battery, locating the crankshaft sensor, removing the old sensor from the car, putting a new sensor in the place of the old one and reconnecting the battery. When properly applied, these steps lead to faultless crankshaft sensor replacement.Full Answer >