Editing Ignition system (section)

{{Short description|Electric spark system to ignite a fuel-air mixture}}
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 | image1       = Hondacoilpack.jpg
 | caption1     = [[Coil-on-plug ignition]] device
 | image2       = Distributor cap of AMC inline-6, top.jpg
 | caption2     = [[Distributor cap]]
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'''Ignition systems''' are used by [[heat engine]]s to initiate combustion by igniting the fuel-air mixture. In a [[spark-ignition engine|spark ignition]] versions of the [[internal combustion engine]] (such as petrol engines), the ignition system creates a spark to ignite the fuel-air mixture just before each [[Stroke_(engine)#Combustion-power-expansion_stroke|''combustion'' stroke]]. [[Gas turbine]] engines and [[rocket engine]]s normally use an ignition system only during start-up.

[[Diesel engine]]s use ''compression ignition'' to ignite the fuel-air mixture using the heat of compression and therefore do not use an ignition system. They usually have [[Glow plug (diesel engine)|glowplugs]] that preheat the [[combustion chamber]] to aid starting in cold weather.

Early cars used [[ignition magneto]] and [[trembler coil]] systems, which were superseded by [[Distributor]]-based systems (first used in 1912). Electronic ignition systems (first used in 1968) became common towards the end of the 20th century, with [[coil-on-plug ignition|coil-on-plug]] versions of these systems becoming widespread since the 1990s.