Chrysler 300/300 Touring/300C, Dodge Magnum. Manual — part 1773
20. Fold the foam pad covering access cover for
modules back into place.
21. Install rear lower seat cushion
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FUEL DELIVERY - DIESEL
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22. Rear lower seat cushion installed.
23. Fill fuel tank.
24. Connect negative battery cable.
25. Fill fuel tank. Use the scan tool to pressurize the
fuel system. Check for leaks.
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FUEL DELIVERY - DIESEL
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FUEL INJECTION
TABLE OF CONTENTS
page
page
FUEL INJECTION
MEMORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SYSTEM DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . 174
TORQUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
FUEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
PEDAL-ACCELERATOR
SENSOR-CRANKSHAFT POSITION
INJECTOR-FUEL
SENSOR-INLET AIR TEMPERATURE
ACTUATOR-MANIFOLD TUNE VALVE
SENSOR-MANIFOLD ABSOLUTE PRESSURE
SENSOR-OXYGEN
SHORT RUNNER VALVE
THROTTLE BODY
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FUEL INJECTION
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FUEL INJECTION
OPERATION
INJECTION SYSTEM
All engines used in this section have a sequential Multi-Port Electronic Fuel Injection system. The MPI system is
computer regulated and provides precise air/fuel ratios for all driving conditions. The Powertrain Control Module
(PCM) operates the fuel injection system.
The PCM regulates:
•
Ignition timing
•
Air/fuel ratio
•
Emission control devices
•
Cooling fan
•
Charging system
•
Idle speed
•
Vehicle speed control
Various sensors provide the inputs necessary for the PCM to correctly operate these systems. In addition to the
sensors, various switches also provide inputs to the PCM.
The PCM can adapt its programming to meet changing operating conditions.
Fuel is injected into the intake port above the intake valve in precise metered amounts through electrically operated
injectors. The PCM fires the injectors in a specific sequence. Under most operating conditions, the PCM maintains
an air fuel ratio of 14.7 parts air to 1 part fuel by constantly adjusting injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening and closing the ground path to the injector. Engine RPM (speed)
and manifold absolute pressure (air density) are the primary inputs that determine injector pulse width.
MODES OF OPERATION
As input signals to the PCM change, the PCM adjusts its response to output devices. For example, the PCM must
calculate a different injector pulse width and ignition timing for idle than it does for Wide Open Throttle (WOT).
There are several different modes of operation that determine how the PCM responds to the various input signals.
There are two different areas of operation, OPEN LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives input signals and responds according to preset PCM programming.
Inputs from the upstream and downstream heated oxygen sensors are not monitored during OPEN LOOP modes,
except for heated oxygen sensor diagnostics (they are checked for shorted conditions at all times).
During CLOSED LOOP modes the PCM monitors the inputs from the upstream and downstream heated oxygen
sensors. The upstream heated oxygen sensor input tells the PCM if the calculated injector pulse width resulted in
the ideal air-fuel ratio of 14.7 to one. By monitoring the exhaust oxygen content through the upstream heated oxy-
gen sensor, the PCM can fine tune injector pulse width. Fine tuning injector pulse width allows the PCM to achieve
optimum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation, the following must occur:
1. Engine coolant temperature must be over 35°F.
•
If the coolant is over 35°F the PCM will wait 38 seconds.
•
If the coolant is over 50°F the PCM will wait 15 seconds.
•
If the coolant is over 167°F the PCM will wait 3 seconds.
2. For other temperatures the PCM will interpolate the correct waiting time.
3. O2 sensor must read either greater than 0.745 volts or less than 0.29 volt.
4. The multi-port fuel injection systems has the following modes of operation:
•
Ignition switch ON (Zero RPM)
•
Engine start-up
•
Engine warm-up
•
Cruise
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FUEL INJECTION
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