Ignition timing Ignition timing In a spark ignition internal combustion engine, Ignition timing refers to 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 need for advancing (or retarding) the timing of the spark is because fuel does not completely burn the instant the spark fires, the combustion gases take a period of time to expand and the angular or rotational speed of the engine can lengthen or shorten the time frame in which the burning and expansion should occur. In a
Ignition interlock device Ignition interlock device An ignition interlock device or breath alcohol ignition interlock device (IID or BAIID) is a breathalyzer for an individual's vehicle. It requires the driver to blow into a mouthpiece on the device before starting the vehicle. If the resultant breath-alcohol concentration analyzed result is greater than the programmed blood alcohol concentration (which varies between countries), the device prevents the engine from being started. The interlock device is located inside the vehicle, near the driver’s seat, and is directly connected to the engine’s ignition system. An ignition interlock interrupts the signal from the ignition to the starter until