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Home >> Jeep >> 1990 >> Wrangler L6-258 4.2L VIN T 2-bbl >> Repair and Diagnosis >> Powertrain Management >> Relays and Modules - Powertrain Management >> Relays and Modules - Computers and Control Systems >> Engine Control Module >> Description and Operation >> General Operation
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General Operation

The Micro Computer Unit (MCU) monitors various engine sensors that indicate engine operating conditions. One of these signals comes from the distributor and is used to determine crankshaft position and speed to calculate ignition timing. The MCU uses the crankshaft position and speed information along with the other sensor inputs to modify the ignition signal that is sent to the ignition control module. The MCU also controls the air-fuel ratio.
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