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Auto-ignition of engine oil droplets (Can be solved by using an oil catch tank) [3] Insufficient oil in the engine; Ignition timing too far advanced; Too much air/too little fuel (octane) to withstand pressures (too much air causes too much pressure for the octane to handle, too little fuel reduces the octane to handle the pressurized air) [5]
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.
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.
In fuel injected engines, the throttle body is the part of the air intake system that controls the amount of air flowing into the engine, in response to driver accelerator pedal input in the main. The throttle body is usually located between the air filter box and the intake manifold, and it is usually attached to, or near, the mass airflow sensor.
Stuck throttle (unrelated to pedal position) [12] [13] Shorting of tin whiskers [14] [15] Diesel engine runaway: Diesel engine power is governed by the amount of fuel supplied. Excessive pressure in the crankcase can force mist of engine oil into the intake manifold, which can be burned in the same fashion as Diesel fuel, thus causing runaway.
Although the IAC is supposed to last the vehicle's lifetime, various reasons may cause it to fail/malfunction prematurely. The most common failure mode is partial/complete jamming of the actuator (due to dirt/dust or even oil) where it cannot be smoothly controlled. The result is an engine that fails to maintain idle RPM and frequently stalls.
The advent of concern about fuel economy and emissions had major impacts on engine design. Some of the trade-offs reduced throttle response. Most new cars employ a drive-by-wire system, which includes electronic throttle control and can itself either reduce or increase throttle response (Depending on whether or not it's being employed on a performance car).
Ordinarily, the power is cut by partially closing a throttle. However, the extra work done in pulling air through the throttle reduces efficiency. If the fuel/air ratio is reduced, then lower power can be achieved with the throttle closer to fully open, and the efficiency during normal driving (below the maximum torque capability of the engine ...