B350 1 Ton Van V8-5.9L VIN Z (1992)
Engine Control Module: Description and Operation
Modes of Operation
Ignition Switch On
This is an Open Loop mode. When the Dual-Point Fuel Injection system is activated by the ignition switch, the following actions occur:
^
Engine controller determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
^
The engine controller monitors the coolant temperature sensor input. The engine controller modifies fuel strategy based on this input.
When the key is in the ON position, the auto shutdown (ASD) relay is energized for 0.5 seconds. If the engine controller does not receive an input
from the distributor pick-up within three seconds, it will deenergize the ASD relay.
Engine Start-Up
This is an Open Loop mode. The following actions occur when the starter motor is engaged:
^
If the engine controller receives a distributor signal, it will energize the auto shutdown (ASD) relay. This supplies battery voltage to the fuel
pump, fuel injector, ignition coil, and oxygen sensor heating element. If the engine controller does not receive a distributor input, the ASD
relay will not be energized.
^
The engine controller compares the current MAP value with the atmospheric pressure value it received during the Key-On mode. This is done
when the engine is operating and idling within ±64 rpm of the target rpm. If a minimum difference between the two is not detected, a
pneumatic fault code is set into memory.
Once the ASD relay has been energized, the engine controller:
^
Supplies a ground path to the injectors. 5.9L engines are pulsed 8 times instead of the normal 4 times.
^
Determines injector pulse width based on coolant temperature, barometric pressure (MAP sensor), and number of engine revolutions since
cranking was initiated.
^
Monitors coolant temperature sensor, distributor pick-up, MAP sensor, throttle body temperature sensor and throttle position sensor. The
engine controller determines correct ignition timing based on these inputs.
Engine Warm-Up
This is an Open Loop mode. The following inputs are received by the engine controller:
^
Coolant temperature
^
Idle contact switch (closed throttle switch)
^
Manifold absolute pressure
^
Engine speed (distributor pick-up)
^
Throttle body temperature sensor
^
Throttle position
^
Park/neutral switch (auto trans)
^
A/C switch
^
Battery voltage
^
Vehicle distance (speed) sensor
The engine controller provides a ground path for the injectors to precisely control injector pulse width. This is done by switching the ground on
and off. On 5.9L engines, the injectors are fired 4 times per engine revolution. The engine controller adjusts engine idle speed, throttle stop angle,
and ignition timing.
