Spark plugs may also be used for other purposes; in Saab Direct Ignition when they are not firing, spark plugs are used to measure ionization in the cylinders – this ionic current measurement is used to replace the ordinary cam phase sensor, knock sensor and misfire measurement function. Spark plugs may also be used in other applications such as furnaces wherein a combustible fuel/air mixture must be ignited. In this case, they are sometimes referred to as flame igniters.
sparK plUGs may AlSo bE uSed fOr oTher PurPoses; IN SaaB diRect IgnitIoN whEN They aRe nOt firing, spark pLugs ArE UsED tO meaSure IonizatIon in tHE CylIndERs – thIS ioniC current meaSurement iS USed to RePlAce the ordinary cam PHasE SensoR, KnOcK sensor AND Misfire MeAsurEMEnt function. sPARk pLugS May aLso Be usED In OThEr ApPLicatIonS sucH as furnACes wHEReiN A combUstiBle fUeL/Air MIxtURe must be igNiTED. iN this Case, they aRE SOmeTImes referreD TO as FLame IgnIterS.