Caravan FWD V6-3.3L VIN 3 Flex Fuel (2001)
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Wide Open Throttle
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Ignition switch OFF
5. The engine start-up (crank), engine warm-up, deceleration with fuel shutoff and wide open throttle modes are OPEN LOOP modes. Under
most operating conditions, the acceleration, deceleration (with A/C ON), idle and cruise modes, with the engine at operating temperature are
CLOSED LOOP modes.
Ignition Switch ON (Zero RPM) Mode
When the ignition switch activates the fuel injection system, the following actions occur:
The PCM monitors the engine coolant temperature sensor and throttle position sensor input. The PCM determines basic fuel injector pulse width
from this input.
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The PCM determines atmospheric air pressure from the MAP sensor input to modify injector pulse width.
When the key is in the ON position and the engine is not running (zero rpm), the Auto Shutdown (ASD) and fuel pump relays de-energize after
approximately 1 second. Therefore, battery voltage is not supplied to the fuel pump, ignition coil, fuel injectors and heated oxygen sensors.
Engine Start-up Mode
This is an OPEN LOOP mode. If the vehicle is in park or neutral (automatic transaxles) or the clutch pedal is depressed (manual transaxles) the
ignition switch energizes the starter relay. The following actions occur when the starter motor is engaged.
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If the PCM receives the camshaft position sensor and crankshaft position sensor signals, it energizes the Auto Shutdown (ASD) relay and fuel
pump relay. If the PCM does not receive both signals within approximately one second, it will not energize the ASD relay and fuel pump relay.
The ASD and fuel pump relays supply battery voltage to the fuel pump, fuel injectors, ignition coil and heated oxygen sensors.
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The PCM energizes the injectors (on the 69 degree falling edge) for a calculated pulse width until it determines crankshaft position from the
camshaft position sensor and crankshaft position sensor signals. The PCM determines crankshaft position within 1 engine revolution.
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After determining crankshaft position, the PCM begins energizing the injectors in sequence. It adjusts injector pulse width and controls
injector synchronization by turning the individual ground paths to the injectors ON and OFF.
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When the engine idles within ± 64 RPM of its target RPM, the PCM compares current MAP sensor value with the atmospheric pressure value
received during the Ignition Switch ON (zero RPM) mode.
Once the ASD and fuel pump relays have been energized, the PCM determines injector pulse width based on the following:
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Battery voltage
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Engine coolant temperature
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Engine RPM
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Inlet/intake air temperature (IAT)
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MAP
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Throttle position
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The number of engine revolutions since cranking was initiated
During Start-up the PCM maintains ignition timing at 9 ° BTDC.
Engine Warm-up Mode
This is an OPEN LOOP mode. The following inputs are received by the PCM:
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Engine coolant temperature
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Manifold Absolute Pressure (MAP)
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Inlet/intake air temperature (IAT)
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Crankshaft position (engine speed)
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Camshaft position
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Knock sensor
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Throttle position
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A/C switch
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Battery voltage
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Vehicle speed
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Speed control
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O2 sensors
The PCM adjusts injector pulse width and controls injector synchronization by turning the individual ground paths to the injectors ON and OFF.
The PCM adjusts ignition timing and engine idle speed. Engine idle speed is adjusted through the idle air control motor.
Cruise Or Idle Mode
When the engine is at operating temperature this is a CLOSED LOOP mode. During cruising or idle the following inputs are received by the PCM:
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Inlet/intake air temperature
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Engine coolant temperature
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Manifold absolute pressure
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Crankshaft position (engine speed)
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Camshaft position
