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Home >> Hummer >> 2009 >> H3 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 3.7L - Introduction >> Description and Operation >> Electronic Ignition System Description >> Electronic Ignition (EI) System Operation

Electronic Ignition (EI) System Operation

The electronic ignition (EI) system produces and controls the high energy secondary spark. This spark ignites the compressed air/fuel mixture at precisely the correct time, providing optimal performance, fuel economy, and control of exhaust emissions. The engine control module (ECM) primarily collects information from the crankshaft position (CKP) and camshaft position (CMP) sensors to control the sequence, dwell, and timing of the spark.