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In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
This causes an incomplete burn which causes the fumes to explode in the exhaust system along with an audible pop or bang sound. This is a result of working equipment, and is unlikely to cause damage. A fuel-injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air ...
Pressure in cylinder pattern in dependence on ignition timing: (a) - misfire, (b) too soon, (c) optimal, (d) too late. In a spark ignition internal combustion engine, ignition timing is the timing, relative to the current piston position and crankshaft angle, of the release of a spark in the combustion chamber near the end of the compression stroke.
A bad crank position sensor can worsen the way the engine idles, or the acceleration behaviour. If the engine is revved up with a bad or faulty sensor, it may cause misfiring, motor vibration or backfires. Acceleration might be hesitant, and abnormal shaking during engine idle might occur. In the worst case, the car may not start.
The reduced engine speeds allow more time for autoignition chemistry to complete thus promoting the possibility of pre-ignition and so called "mega-knock". Under these circumstances, there is still significant debate as to the sources of the pre-ignition event. [3] Pre-ignition and engine knock both sharply increase combustion chamber temperatures.
LSPI events are random and infrequent, and their effects on impacted vehicles can include very high-pressure spikes, loud knocking noises and sometimes catastrophic engine damage. [4] It's commonly known as "Detonation or Knock". Engine management systems can overcome pre ignition by the means of a knock or detonation sensor.
The dieseling phenomenon occurs not just because the compression ratio is sufficient to cause auto-ignition of the fuel, but also because a hot spot inside the cylinder (spark plug electrode, combustion-chamber/valve edge or even excess carbon) starts combustion. An automobile engine that is dieseling will typically sputter, then gradually stop ...
Moreover, flame blowoff of an aero-gas-turbine engine in mid-flight is clearly dangerous (see flameout). Because of these hazards, the engineering design process of engines involves the determination of a stability map (see figure). This process identifies a combustion-instability region and attempts to either eliminate this region or moved the ...