Chrysler Le Baron, Dodge Dynasty, Plymouth Acclaim. Manual — part 44
CRUISE OR IDLE MODE
When the engine is at operating temperature, this is
a CLOSED LOOP mode. During cruising speed the
following inputs are received by the PCM:
• engine coolant temperature
• knock sensor
• manifold absolute pressure
• engine speed (crankshaft position sensor)
• throttle position
• exhaust gas oxygen content
• A/C control positions
• battery voltage
The PCM provides a ground path for the injectors to
precisely control injector pulse width. The PCM adjusts
engine idle speed and ignition timing. The PCM con-
trols the air/fuel ratio according to the oxygen content
in the exhaust gas.
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recognizes
an abrupt increase in throttle position or MAP pres-
sure as a demand for increased engine output and
vehicle acceleration. The PCM increases injector pulse
width in response to increased fuel demand.
DECELERATION MODE
This is a CLOSED LOOP mode. During deceleration
the following inputs are received by the PCM:
• engine coolant temperature
• knock sensor
• manifold absolute pressure
• engine speed (crankshaft position sensor)
• throttle position
• exhaust gas oxygen content
• A/C control positions
• battery voltage
The PCM may receive a closed throttle input from
the throttle position sensor (TPS) at the same time it
senses an abrupt decrease in manifold pressure. This
indicates a hard deceleration. The PCM modifies the
injector sequence. This helps maintain better control
of the air-fuel mixture.
WIDE OPEN THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are received
by the PCM:
• engine coolant temperature
• knock sensor
• manifold absolute pressure
• engine speed (crankshaft position sensor)
• throttle position
When the PCM senses a wide open throttle condi-
tion it will de-energize the air conditioning relay.
This disables the air conditioning system.
The exhaust gas oxygen content input is not ac-
cepted by the PCM during wide open throttle opera-
tion. The PCM will enrichen the air/fuel ratio to
increase performance and compensate for increased
combustion chamber temperature.
IGNITION SWITCH OFF MODE
This is an OPEN LOOP mode. When the ignition
switch is turned to the OFF position, the following
occurs:
• All outputs are turned off.
• No inputs are monitored.
• The PCM shuts down.
Fig. 20 Throttle Body
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THROTTLE BODY
The throttle body assembly is located on the left
end of the intake manifold plenum (Fig. 20). The
throttle body houses the throttle position sensor and
the idle air control motor. Air flow through the throt-
tle body is controlled by a cable operated throttle
blade located in the base of the throttle body.
FUEL SUPPLY CIRCUIT
Fuel is pumped to the fuel rail by an electrical
pump in the fuel tank. The pump inlet is fitted with
a strainer to prevent water and other contaminants
from entering the fuel supply circuit.
Fuel pressure is controlled to a preset level above
intake manifold pressure by a pressure regulator.
The regulator is mounted on the fuel rail (Fig. 21).
The regulator uses intake manifold pressure as a ref-
erence.
FUEL INJECTORS AND FUEL RAIL ASSEMBLY
Four fuel injectors are retained in the fuel rail by
lock rings. The rail and injector assembly are in-
stalled with the injectors inserted into recessed holes
in the intake manifold.
FUEL PRESSURE REGULATOR
The pressure regulator is a mechanical device lo-
cated on the fuel rail, downstream of the fuel injec-
tors (Fig. 22). The regulator maintains a constant
380 kPa (55 psi) across the fuel injector tip.
The regulator contains a spring loaded rubber dia-
phragm that covers the fuel return port. When the
fuel pump is operating, fuel flows past the injectors
into the regulator, and is restricted from flowing any
further by the blocked return port. When fuel pres-
sure reaches 380 kPa (55 psi) it pushes on the dia-
phragm, compresses the spring, and uncovers the
fuel return port. The diaphragm and spring con-
stantly move from an open to closed position to keep
the fuel pressure constant.
Fig. 21 Fuel Supply Circuit
Fig. 22 Fuel Pressure Regulator
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FUEL SYSTEMS
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2.2L TURBO III MULTI-PORT FUEL INJECTION—GENERAL DIAGNOSIS
INDEX
page
page
Fuel System Diagram
. . . . . . . . . . . . . . . . . . . . . 95
Visual Inspection
. . . . . . . . . . . . . . . . . . . . . . . . . 95
FUEL SYSTEM DIAGRAM
Refer to the System Operation portion of this sec-
tion for descriptions of the components shown in Fig.
1.
VISUAL INSPECTION
Perform a visual inspection for loose, disconnected,
or misrouted wires and hoses before diagnosing or
servicing the fuel injection system. A visual check
helps save unnecessary test and diagnostic time. A
thorough visual inspection includes the following
checks:
(1) Check the ignition coil electrical connections
(Fig. 2).
(2) Verify the harness connector is attached to the
canister purge solenoid (Fig. 3).
(3) Verify the harness connector is attached to the
wastegate solenoid (Figs. 3).
Fig. 1 Multi-port Fuel Injection Components
Fig. 2 Ignition Coil Electrical Connection
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14 - 95
(4) Verify the harness connector is attached to the
MAP sensor (Fig. 4).
(5) Check vacuum hose connections between vac-
uum source and canister purge, wastegate, and baro-
metric read solenoids (Figs. 3 and 4).
(6) Verify hoses are securely attached to vapor
canister (Fig. 5).
(7) Verify the generator wiring and belt are cor-
rectly installed and tightened.
(8) Check ignition cable routing and attachment
(Fig. 6).
(9) Check oil pressure sending unit electrical con-
nection (Fig. 7).
(10) Check the camshaft position sensor and crank-
shaft position sensor electrical connections (Figs. 7
and 8).
(11) Check radiator fan electrical connector.
(12) Check electrical connector at the coolant tem-
perature sensor (Fig. 9).
(13) Inspect the engine temperature sensor electri-
cal connection (Fig. 9).
(14) Check the power brake booster and speed con-
trol connections (Fig. 10).
Fig. 6 Ignition Cable Mounting and Attachment
Fig. 7 Oil Pressure Sending Unit and Crankshaft
Position Sensor
Fig. 3 Solenoid Connections
Fig. 4 Barometric/MAP Solenoid Hose Connections
Fig. 5 Vapor Canister
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FUEL SYSTEMS
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