coolant CHRYSLER VOYAGER 1996 Service Manual

(10) Disconnect MAP Sensor electrical connection
(Fig. 34).
(11) Remove EGR tube flange from intake ple-
num.
(12) Remove vacuum harness connectors from
intake plenum (Fig. 34).
(13) Remove cylinder head to intake plenum strut
(Fig. 35)
(14) Remove the engine mounted ground strap.
(15) Remove the fuel hose quick connect fitting
from the fuel line by using an open end wrench push-
ing in on the plastic ring located on the end of the
fittings. Gently pull the fitting from the fuel line
(Fig. 36).
WARNING: WRAP A SHOP TOWEL AROUND
HOSES TO CATCH ANY GASOLINE SPILLAGE DUR-
ING REMOVAL.
(16) Remove direct ignition system (DIS) coils and
generator bracket to intake manifold bolt (Fig. 37).(17) Remove bolts from generator to intake mani-
fold bracket. Loosen top generator mounting bolt,
and move bracket up so intake manifold can clear
mounting studs (Fig. 38).
(18) Remove intake manifold bolts and remove the
manifold (Fig. 38).
(19) Cover intake manifold with suitable cover
when servicing (Fig. 39).
(20) Remove fuel tube retainer bracket screw and
fuel rail attaching bolts (Fig. 39). Spread the retainer
bracket to allow fuel tube removal clearance.
(21) Disconnect cam sensor and coolant tempera-
ture sensor (Fig. 40).
(22) Remove fuel injector wiring clip from intake
manifold water tube.
(23) Remove fuel rail. Be careful not to damage
the rubber injector O-rings upon removal from their
ports (Fig. 41).
(24) Remove upper radiator hose, bypass hose and
rear intake manifold hose (Fig. 42).
Fig. 34 Vacuum and Electrical Connections to Intake
Manifold
Fig. 35 Intake Manifold Plenum Support Bracket
Fig. 36 Quick Connect Fuel Fitting to Fuel Line
Fig. 37 Ignition Coils
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 13
REMOVAL AND INSTALLATION (Continued)

(25) Remove intake manifold bolts. Remove intake
manifold.
(26) Inspect and clean manifold. Refer to Cleaning
and Inspection outlined in this section for proce-
dures.
WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
(27) Remove intake manifold seal retainers screws
(Fig. 43). Remove intake manifold gasket.
INSTALLATION
(1) Clean all surfaces of cylinder block and cylin-
der heads.
(2) Place a drop (approximately 1/4 in. diameter)
of MopartSilicone Rubber Adhesive Sealant or
equivalent, onto each of thefourmanifold to cylinder
head gasket corners (Fig. 44).(3) Carefully install the new intake manifold gas-
ket (Fig. 43). Torque end seal retainer screws to 12
N´m (105 in. lbs.).
(4) Install intake manifold and bolts and torque to
1 N´m (10 in. lbs.). Then torque bolts to 22 N´m (200
in. lbs.) in sequence shown in (Fig. 42). Then torque
again to 22 N´m (200 in. lbs.). After intake manifold
is in place,inspect to make sure seals are in
place.
Fig. 38 Intake Manifold Plenum Bolts and Nuts
Fig. 39 Fuel Rail Attaching Bolts
Fig. 40 Coolant Temperature Sensor Electrical
Connector
Fig. 41 Fuel Rail Removal
11 - 14 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
REMOVAL AND INSTALLATION (Continued)

(5) Make sure the injector holes are clean and all
plugs have been removed.
(6) Lube injector O-ring with a drop of clean
engine oil to ease installation.(7) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports (Fig. 41).
(8) Install the fuel rail attaching bolts and torque
to 22 N´m (200 in. lbs.) (Fig. 39).
(9) Install fuel tube retaining bracket screw and
torque to 4 N´m (35 in. lbs.) (Fig. 39).
(10) Connect cam sensor and coolant temperature
sensor (Fig. 40).
(11) Remove covering on lower intake manifold
and clean surface.
(12) Place the new intake manifold gasket on
lower manifold. Put upper manifold into place and
install bolts and nuts finger tight.
NOTE: At no time should the studs be replaced
with a bolt and washer.
(13) Install the generator bracket to intake mani-
fold bolt and the cylinder head to intake manifold
strut bolts. (Do not torque.)
(14) Torque intake manifold bolts to 28 N´m (250
in. lbs.) following torque sequence in (Fig. 38).
(15) Torque generator bracket to intake manifold
bolt to 54 N´m (40 ft. lbs.).
(16) Torque the cylinder head to intake manifold
strut bolts to 54 N´m (40 ft. lbs.) (Fig. 35).
(17) Connect ground strap and MAP sensor electri-
cal connectors.
(18) Connect vacuum harness to intake plenum
(Fig. 34).
(19) Using a new gasket, connect the EGR tube
flange to the intake manifold and torque to 22 N´m
(200 in. lbs.).
(20) Clip wiring harness into the hole in the throt-
tle cable bracket.
(21) Connect the wiring connectors to the throttle
position sensor (TPS) and Automatic Idle Speed (AIS)
motor (Fig. 33).
(22) Connect vacuum harness to throttle body (Fig.
33).
(23) Install the direct ignition system (DIS) coils.
Torque fasteners to 12 N´m (105 in. lbs.) (Fig. 37).
(24) Lubricate the end of the chassis fuel tube
with 30 wt. oil. Connect fuel supply hose to chassis
fuel tube assembly. Pull back on the quick connect
fitting to ensure complete insertion (Fig. 36). (Refer
to Fuel Hoses, Clamps and Quick Connect Fittings in
Group 14 Fuel Systems).
(25) Install throttle cable. Refer to Group 14 Fuel
System for procedure.
(26) Connect fuel injector wiring harness.
(27) Install air cleaner and hose assembly.
(28) Connect negative battery cable. Fill Cooling
System. See Cooling System, Group 7.
(29) With the DRB Scan Tool use ASD Fuel Sys-
tem Test to pressurize system to check for leaks.
Fig. 42 Intake Manifold Removal and Installation
Fig. 43 Intake Manifold Gasket
Fig. 44 Intake Manifold Gasket Sealing
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 15
REMOVAL AND INSTALLATION (Continued)

(3) Remove air inlet resonator (Fig. 36).
(4) Remove throttle cable (Fig. 37).
(5) Disconnect electrical connectors from the idle
air control motor and Throttle Position Sensor (TPS).
(6) Remove vacuum hose harness from throttle
body (Fig. 38).
(7) Remove electrical connector from the coolant
temperature sensor (Fig. 39).
(8) Remove vacuum connections from air intake
plenum vacuum connector (Fig. 39).
(9) Remove the fuel hose quick connect fitting from
the chassis tube (Fig. 40).Refer to Fuel Hoses,
Clamps and Quick Connect Fittings in this Sec-
tion.Place a shop towel under the connections to
absorb any fuel spilled from the fitting.WARNING: WRAP A SHOP TOWEL AROUND
HOSES TO CATCH ANY GASOLINE SPILLAGE.
Fig. 36 Air Inlet Resonator
Fig. 37 Throttle Cable Attachment
Fig. 38 Electrical and Vacuum Connection to
Throttle Body
Fig. 39 Coolant Temperature Sensor Electrical
Connections
Fig. 40 Fuel Line Quick Disconnect
14 - 20 FUEL SYSTEMNS
REMOVAL AND INSTALLATION (Continued)

(10) Remove air intake plenum to intake manifold
mounting fasteners (Fig. 41).
(11) Remove ignition coil.
(12) Remove air intake plenum (Fig. 42).
(13) Cover intake manifold while servicing injector
fuel rail.
(14) Disconnect fuel injector wiring harness from
engine wiring harness.
CAUTION: Do not damage the injector O-Rings
when removing the injectors and fuel rail assembly.
(15) Remove fuel rail mounting bolts. Lift fuel rail
assembly off of intake manifold.
INSTALLATION
(1) Ensure injectors are seated into the receiver
cup of fuel rail with lock ring in place.
(2) Make sure the injector holes in the manifold
are clean.
(3) To ease installation, lubricate injector O-ring
with a drop of clean engine oil.
(4) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports.(5) Install fuel rail attaching bolts. Tighten bolts to
13 N´m (115 in. lbs.) torque.
(6) Install fuel supply and return tube holddown
bolt and the vacuum crossover tube holddown bolt.
Tighten bolts to 10 N´m (95 in. lbs.) torque.
(7) Connect fuel injector wiring harness to engine
wiring harness.
(8) Remove covering from lower intake manifold
and clean surface.
(9) Place intake manifold gasketswith beaded
sealerupon lower manifold. Put air intake in place.
Install ignition coil. Install attaching fasteners and
tighten to 13 N´m (115 in. lbs.) torque.
(10) Connect fuel line to fuel rail.
(11) Connect vacuum harness to air intake ple-
num.
(12) Connect coolant temperature sensor electrical
connector to sensor.
(13) Connect PCV and brake booster supply hose
to intake plenum.
(14) Connect idle air control motor and Throttle
Position Sensor (TPS) electrical connectors.
(15) Connect vacuum vapor harness to throttle
body.
(16) Install throttle cable.
(17) Install air inlet resonator.
(18) Connect negative cable to battery.
CAUTION: When using the ASD Fuel System Test,
the ASD relay and fuel pump relay remain energized
for 7 minutes or until the test is stopped, or until
the ignition switch is turned to the Off position.
(19) With the ignition key in ON position, access
the DRB scan tool ASD Fuel System Test to pressur-
ize the fuel system. Check for leaks.
FUEL INJECTOR RAILÐ3.3/3.8L
WARNING: THE 3.3/3.8L MPI FUEL SYSTEM IS
UNDER A CONSTANT PRESSURE OF APPROXI-
MATELY 330 KPA (49 PSI), 3.3L USES APPROXI-
MATELY 379 KPA (55 PSI). PERFORM FUEL
PRESSURE RELEASE PROCEDURE BEFORE SER-
VICING THE FUEL RAIL OR FUEL INJECTORS.
REMOVAL
(1) Perform fuel system pressure release proce-
dure.
(2) Disconnect negative cable from battery.
(3) Remove intake manifold cover.
(4) Remove air inlet resonator (Fig. 36).
(5) Remove throttle cable and speed control cable
(if equipped) (Fig. 43) from throttle lever and
bracket.
Fig. 41 Air Intake Plenum to Intake Manifold
Attaching Fasteners
Fig. 42 Removing Air Intake Plenum
NSFUEL SYSTEM 14 - 21
REMOVAL AND INSTALLATION (Continued)

(13) Remove Direct Ignition System (DIS) coils
(Fig. 49).
(14) Remove generator bracket to intake manifold
bolt.(15) Remove intake mounting manifold bolts and
rotate manifold back over rear valve cover (Fig. 50).
(16) Cover intake manifold with suitable cover
when servicing (Fig. 51).
(17) Remove fuel tube retainer bracket screw and
fuel rail attaching bolts (Fig. 51). Spread the retainer
bracket to allow fuel tube removal clearance.
(18) Disconnect camshaft position sensor (Fig. 52)
and engine coolant temperature sensor.
(19) Remove fuel rail. Be careful not to damage
the injector O-rings upon removal from their ports
(Fig. 53).
INSTALLATION
(1) Ensure injector holes are clean. Replace
O-rings if damaged.
(2) Lubricate injector O-rings with a drop of clean
engine oil to ease installation.
(3) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports.
Fig. 47 Map Sensor
Fig. 48 Fuel Line Quick Disconnect
Fig. 49 Ignition Coils
Fig. 50 Intake Manifold Bolts
Fig. 51 Fuel Rail Attaching Bolts
NSFUEL SYSTEM 14 - 23
REMOVAL AND INSTALLATION (Continued)

(4) Install the fuel rail mounting bolts. Tighten
bolts to 22 N´m (200 in. lbs.) torque (Fig. 51).
(5) Install fuel tube retaining bracket screw.
Tighten screw to 4 N´m (35 in. lbs.) torque.
(6) Connect electrical connectors to camshaft posi-
tion sensor and engine coolant temperature sensor.
(7) Remove covering on lower intake manifold and
clean surface.
(8) Place intake manifold gasket on lower mani-
fold. Put upper manifold into place and install bolts
finger tight.
(9) Install the generator bracket to intake mani-
fold bolt and the cylinder head to intake manifold
strut bolts (do not tighten.)(10) Following the tightening sequence in (Fig. 50),
tighten intake manifold bolts to 28 N´m (250 in. lbs.)
torque.
(11) Tighten generator bracket to intake manifold
bolt to 54 N´m (40 ft. lbs.) torque.
(12) Tighten the cylinder head to intake manifold
strut bolts to 54 N´m (40 ft. lbs.) torque.
(13) Connect ground strap and MAP sensor electri-
cal connector.
(14) Connect vacuum harness to intake plenum.
Connect PCV system hoses.
(15) Using a new gasket, connect the EGR tube to
the intake manifold plenum. Tighten screws to 22
N´m (200 in. lbs.) torque.
(16) Connect electrical connectors to the TPS and
idle air control motor.
(17) Connect vacuum harness to throttle body.
(18) Install the direct ignition system (DIS) coils.
Tighten fasteners to 12 N´m (105 in. lbs.) torque.
(19) Install fuel hose quick connector fitting to
chassis tubes.Refer to Fuel Hoses, Clamps and
Quick Connect Fittings in this Section.Push the
fitting onto the chassis tube until it clicks into place.
Pull on the fitting to ensure complete insertion.
(20) Install throttle cable and speed control cable
(if equipped).
(21) Install air inlet resonator.
(22) Connect negative cable to battery.
CAUTION: When using the ASD Fuel System Test,
the ASD relay and fuel pump relay remain energized
for 7 minutes or until the test is stopped, or until
the ignition switch is turned to the Off position.
(23) With the ignition key in ON position, access
the DRB scan tool ASD Fuel System Test to pressur-
ize the fuel system. Check for leaks.
FUEL INJECTORÐ2.4L
The fuel rail must be removed first. Refer to Fuel
Injector Rail Removal in this section.
REMOVAL
(1) Disconnect injector wiring connector from injec-
tor.
(2) Position fuel rail assembly so that the fuel
injectors are easily accessible (Fig. 54).
(3) Rotate injector and pull injector out of fuel rail.
The clip will stay on the injector.
(4) Check injector O-ring for damage. If O-ring is
damaged, it must be replaced. If injector is reused, a
protective cap must be installed on the injector tip to
prevent damage. Replace the injector clip if it is dam-
aged.
(5) Repeat for remaining injectors.
Fig. 52 Camshaft Position Sensor Connector
Fig. 53 Fuel Rail Removal
14 - 24 FUEL SYSTEMNS
REMOVAL AND INSTALLATION (Continued)

FUEL INJECTION SYSTEM
INDEX
page page
GENERAL INFORMATION
INTRODUCTION......................... 30
MODES OF OPERATION.................. 30
DESCRIPTION AND OPERATION
AIR CONDITIONING (A/C) CLUTCH RELAYÐ
PCM OUTPUT......................... 41
AIR CONDITIONING PRESSURE
TRANSDUCERÐPCM INPUT............. 33
AIR CONDITIONING SWITCH SENSEÐ
PCM INPUT........................... 33
AUTOMATIC SHUTDOWN (ASD) SENSEÐ
PCM INPUT........................... 33
AUTOMATIC SHUTDOWN RELAYÐPCM
OUTPUT............................. 42
AUTOMATIC TRANSAXLE CONTROL
MODULEÐPCM OUTPUT................ 44
BATTERY VOLTAGEÐPCM INPUT........... 33
BRAKE SWITCHÐPCM INPUT.............. 33
CAMSHAFT POSITION SENSORÐPCM INPUT . 33
CCDBUS .............................. 32
CRANKSHAFT POSITION SENSORÐPCM
INPUT............................... 35
DATA LINK CONNECTORÐPCM OUTPUT..... 44
DUTY CYCLE EVAP CANISTER PURGE
SOLENOIDÐPCM OUTPUT.............. 43
ELECTRONIC EGR TRANSDUCER
SOLENOIDÐPCM OUTPUT.............. 43
ENGINE COOLANT TEMPERATURE SENSORÐ
PCM INPUT........................... 36
FUEL INJECTORSÐPCM OUTPUT.......... 44
FUEL PUMP RELAYÐPCM OUTPUT......... 42
GENERATOR FIELDÐPCM OUTPUT......... 42
HEATED OXYGEN SENSOR (O2S SENSOR)Ð
PCM INPUT........................... 37
IDLE AIR CONTROL MOTORÐPCM OUTPUT . . 42
IGNITION COILÐPCM OUTPUT............. 45
INTAKE AIR TEMPERATURE SENSORÐPCM
INPUT (2.4L ONLY)..................... 41
KNOCK SENSORÐPCM INPUT............. 38
MALFUNCTION INDICATOR (CHECK ENGINE)
LAMPÐPCM OUTPUT.................. 46
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐPCM INPUT.................. 39
POWERTRAIN CONTROL MODULE (PCM).... 32
PROPORTIONAL PURGE SOLENOID......... 43
SOLID STATE FAN RELAYÐPCM OUTPUT.... 46
SPEED CONTROL SOLENOIDSÐ
PCM OUTPUT......................... 46
SPEED CONTROLÐPCM INPUT............ 39STARTER RELAYÐPCM OUTPUT........... 42
SYSTEM DIAGNOSIS..................... 32
TACHOMETERÐPCM OUTPUT............. 47
THROTTLE BODY....................... 47
THROTTLE POSITION SENSOR (TPS)Ð
PCM INPUT........................... 40
TORQUE CONVERTER CLUTCH SOLENOIDÐ
PCM OUTPUT......................... 46
TRANSAXLE PARK/NEUTRAL SWITCHÐ
PCM INPUT........................... 40
VEHICLE SPEED AND DISTANCEÐ
PCM INPUT........................... 41
DIAGNOSIS AND TESTING
ASD AND FUEL PUMP RELAYS............. 59
CAMSHAFT AND CRANKSHAFT POSITION
SENSOR............................. 61
ENGINE COOLANT TEMPERATURE SENSOR . . 61
HEATED OXYGEN SENSOR............... 61
KNOCK SENSOR........................ 61
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR............................. 60
THROTTLE BODY MINIMUM AIR FLOW
CHECK PROCEDURE................... 62
THROTTLE POSITION SENSOR............ 62
VISUAL INSPECTIONÐ2.4L ENGINE......... 47
VISUAL INSPECTIONÐ3.0L ENGINE......... 52
VISUAL INSPECTIONÐ3.3/3.8L ENGINES..... 55
REMOVAL AND INSTALLATION
AIR CLEANER ELEMENT.................. 70
AUTOMATIC SHUTDOWN (ASD) RELAY...... 64
CAMSHAFT POSITION SENSOR............ 68
CRANKSHAFT POSITION SENSOR.......... 68
DOWNSTREAM OXYGEN SENSOR.......... 69
ENGINE COOLANT TEMPERATURE
SENSORÐ2.4L........................ 70
ENGINE COOLANT TEMPERATURE
SENSORÐ3.0L........................ 71
ENGINE COOLANT TEMPERATURE
SENSORÐ3.3/3.8L..................... 71
FUEL PUMP RELAY...................... 64
IDLE AIR CONTROL MOTOR............... 65
INTAKE AIR TEMPERATURE SENSORÐ2.4L . . . 72
KNOCK SENSOR........................ 70
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ2.4/3.3/3.8L.................. 66
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ3.0L........................ 66
POWERTRAIN CONTROL MODULE.......... 67
PROPORTIONAL PURGE SOLENOID VALVE . . . 66
NSFUEL SYSTEM 14 - 29

THROTTLE BODY....................... 64
THROTTLE POSITION SENSOR............ 65
UPSTREAM OXYGEN SENSOR............. 68
SPECIFICATIONS
TORQUE.............................. 72SPECIAL TOOLS
FUEL................................. 72
GENERAL INFORMATION
INTRODUCTION
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 Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing 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 operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing 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 injec-
tor 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 differ-
ent 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 PCMprogramming. Input from the oxygen (O2S) sensor is
not monitored during OPEN LOOP modes.
During CLOSED LOOP modes the PCM does mon-
itor the O2S sensor input. This input indicates to the
PCM whether or not the calculated injector pulse
width results in the ideal air/fuel ratio of 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. Fine tuning injector
pulse width allows the PCM to achieve optimum fuel
economy combined with low emissions.
The multi-port fuel injection system has the follow-
ing modes of operation:
²Ignition switch ON (zero RPM)
²Engine start-up
²Engine warm-up
²Cruise (Idle)
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
The engine start-up (crank), engine warm-up, and
wide open throttle modes are OPEN LOOP modes.
Under most operating conditions, the acceleration,
deceleration, and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the multi-port fuel injection system is acti-
vated by the ignition switch, the following actions
occur:
²The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
²The PCM monitors the coolant temperature sen-
sor and throttle position sensor input. The PCM mod-
ifies fuel strategy based on this input.
When the key is in the ON position and the engine
is not running (zero rpm), the Automatic Shutdown
(ASD) relay and fuel pump relay are not energized.
Therefore battery voltage is not supplied to the fuel
pump, ignition coil, fuel injectors or oxygen sensor
heating element.
ENGINE START-UP MODE
This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays sup-
ply battery voltage to the fuel pump, fuel injectors,
14 - 30 FUEL SYSTEMNS
SPECIFICATIONS (Continued)

ignition coil, and oxygen sensor heating element. If
the PCM does not receive the camshaft position sen-
sor and crankshaft position sensor signals within
approximately one second, it de-energizes the ASD
relay and fuel pump relay.
The PCM energizes all injectors until it determines
crankshaft position from the camshaft position sen-
sor and crankshaft position sensor signals. The PCM
determines crankshaft position within 1 engine revo-
lution.
After determining crankshaft position, the PCM
begins energizing the injectors in sequence. The PCM
adjusts injector pulse width and controls injector syn-
chronization by turning the individual ground paths
to the injectors On and Off.
When the engine idles within664 RPM of its tar-
get RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode. If
the PCM does not detect a minimum difference
between the two values, it sets a MAP diagnostic
trouble code into memory.
Once the ASD and fuel pump relays have been
energized, the PCM:
²Determines injector pulse width based on engine
coolant temperature, MAP and the number of engine
revolutions since cranking was initiated.
²Monitors the engine coolant temperature sensor,
camshaft position sensor, crankshaft position sensor,
MAP sensor, and throttle position sensor to deter-
mine correct ignition timing.
ENGINE WARM-UP MODE
This is a OPEN LOOP mode. The following inputs
are received by the PCM:
²Engine coolant temperature
²Manifold absolute pressure
²Engine speed (crankshaft position sensor)
²Throttle position
²A/C switch
²Battery voltage
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
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in throttle position or MAP
pressure as a demand for increased engine output
and vehicle acceleration. The PCM increases injector
pulse width in response to increased fuel demand.
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising speed the
following inputs are received by the PCM:²Engine coolant temperature
²Manifold absolute pressure
²Engine speed (crankshaft position sensor)
²Throttle position
²Exhaust gas oxygen content
²A/C control positions
²Battery voltage
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 engine idle speed and ignition
timing. The PCM adjusts the air/fuel ratio according
to the oxygen content in the exhaust gas.
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in throttle position or MAP
pressure 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 decelera-
tion the following inputs are received by the PCM:
²Engine coolant temperature
²Manifold absolute pressure
²Engine speed
²Throttle position
²Exhaust gas oxygen content
²A/C control positions
²Battery voltage
The PCM may receive a closed throttle input from
the Throttle Position Sensor (TPS) when it senses an
abrupt decrease in manifold pressure. This indicates
a hard deceleration. The PCM may reduce injector
pulse width or the number of injectors firing per
engine revolution. This helps maintain better control
of the air/fuel mixture (as sensed through the O2S
sensor).
WIDE OPEN THROTTLE (WOT) MODE
This is an OPEN LOOP mode. During WOT oper-
ation, the following inputs are received by the PCM:
²Engine coolant temperature
²Manifold absolute pressure
²Engine speed
²Throttle position
When the PCM senses WOT condition through the
Throttle Position Sensor (TPS) it will:
²De-energize the air conditioning relay. This dis-
ables the air conditioning system.
The exhaust gas oxygen content input is not
accepted by the PCM during WOT operation. The
PCM will adjust injector pulse width to supply a pre-
determined amount of additional fuel.
NSFUEL SYSTEM 14 - 31
GENERAL INFORMATION (Continued)