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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.
Some engine control units (ECUs) also control the throttle position by electronic throttle control (ETC) or "drive by wire" systems, and if that is done, the position sensor is used in a feedback loop to enable that control. [1] Related to the TPS are accelerator pedal sensors, which often include a wide open throttle (WOT) sensor.
The first person to build a working four-stroke engine, a stationary engine using a coal gas-air mixture for fuel (a gas engine), was German engineer Nicolaus Otto. [4] This is why the four-stroke principle today is commonly known as the Otto cycle and four-stroke engines using spark plugs often are called Otto engines.
On some OHV engines in the 1960s, such as the Ford Taunus V4 engine and Opel CIH engine, the tappet adjustment was done by setting the height of the rocker pivot point (rather than the typical method of a rocker-end adjustment screw). On the 1965-1970 versions of the Opel CIH engine with solid tappets, the tappet adjustment was conducted with ...
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.
The first engine to feature hydraulic lifters was the 1930 Cadillac V16 (Model 452). Hydraulic lifters were nearly universal on cars designed in the 1980s, but some newer cars have reverted to bucket-and-shim mechanical lifters. Although these do not run as quietly and are not maintenance-free, they are cheaper.
Engine designers aim to close the exhaust valve just as the fresh charge from the intake valve reaches it, to prevent either loss of fresh charge or unscavenged exhaust gas. In the diagram, the valve overlap periods are indicated by the overlap of the red and blue arcs. Key: TDC = Top dead centre; BDC = Bottom dead centre; IO = Inlet valve opens
A direct start system as used on a marine slow-speed diesel is required to have up to 12 starts on a non-reversing engine or 6 starts on a reversible, or geared, engine. When starting the engine, compressed air is admitted to whichever cylinder has a piston just over top dead center, forcing it downward. [2]