Magnum SRT-8 V8-6.1L VIN 3 (2006)
Engine Control Module: Description and Operation
MODULE-POWERTRAIN CONTROL
DESCRIPTION
PCM
The Powertrain Control Module (PCM) is located in the engine compartment. The PCM is referred to as NGC.
MODES OF OPERATION
As input signals to the Powertrain Control Module (PCM) change, the PCM adjusts its response to the output devices. For example, the PCM must
calculate different injector pulse width and ignition timing for idle than it does for wide open throttle (WOT).
The PCM will operate in two different modes: Open Loop and Closed Loop.
During Open Loop modes, the PCM receives input signals and responds only according to preset PCM programming. Input from the oxygen (O2S)
sensors is not monitored during Open Loop modes.
During Closed Loop modes, the PCM will monitor the oxygen (O2S) sensors input. This input indicates to the PCM whether or not the calculated
injector pulse width results in the ideal air-fuel ratio. This ratio is 14.7 parts air-to-1 part fuel. By monitoring the exhaust oxygen content through the
O2S sensor, the PCM can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine
performance.
The fuel injection system has the following modes of operation:
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Ignition switch ON
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Engine start-up (crank)
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Engine warm-up
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Idle
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Cruise
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Acceleration
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Deceleration
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Wide open throttle (WOT)
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Ignition switch OFF
The ignition switch On, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The
idle and cruise modes, (with the engine at operating temperature) are Closed Loop modes.
IGNITION SWITCH (KEY-ON) MODE
This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur:
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The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
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The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based on this input.
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Intake manifold air temperature sensor input is monitored.
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Throttle position sensor (TPS) is monitored.
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The auto shutdown (ASD) relay is energized by the PCM for approximately three seconds.
