Power system CHRYSLER VOYAGER 2004 Service Manual

FLEX PLATE
REMOVAL
(1) Remove the transaxle (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 41TE -
REMOVAL).
(2) Remove flex plate attaching bolts.
(3) Remove the flex plate (Fig. 85).
INSTALLATION
(1) Position flex plate with backing plate on the
crankshaft (Fig. 85).
(2) Apply MopartLock & Seal Adhesive to the flex
plate bolts.
(3) Install flex plate bolts (Fig. 85). Tighten bolts
to 95 N´m (70 ft. lbs.).
(4) Install the transaxle (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 41TE - INSTAL-
LATION).
ENGINE MOUNTING
DESCRIPTION
The engine mounting system consist of four
mounts; right and a left side support the powertrain,
and a front and a rear mount control powertrain
torque. The right side mount is a hydro-type (Fig.
86), all others are of molded rubber material.
FRONT MOUNT
REMOVAL
(1) Support the engine and transmission assembly
with a floor jack so it will not rotate.
(2) Remove the front engine mount through bolt
from the insulator and front crossmember mounting
bracket (Fig. 87).
(3) Remove six screws from air dam to allow
access to the front mount screws.
(4) Remove the front engine mount screws and
remove the insulator assembly (Fig. 87).
(5) Remove the front mounting bracket, if neces-
sary (Fig. 87).
INSTALLATION
(1) Install the front mounting bracket, if removed
(Fig. 87).
(2) Install the front engine mount through bolt
from the insulator and front crossmember mounting
bracket (Fig. 87).
(3) Install the insulator assembly and mounting
screws (Fig. 87).
Fig. 85 FLEX PLATE
1 - FLEX PLATE
2 - BOLT (QTY. 8)
3 - BACKING PLATE
Fig. 86 Engine Hydro-type Mount - Right Side
1 - BOLT
2 - BOLT
3 - FRAME RAIL
4 - RIGHT MOUNT - 2.4L ENGINE
5 - RIGHT MOUNT - 3.3/3.8L ENGINE
RSENGINE 3.3/3.8L9 - 131

(3) Install cover and tighten screws to 12 N´m (105
in. lbs.).
(4) If removed, install the oil pressure relief valve.
(Refer to 9 - ENGINE/LUBRICATION/OIL PRES-
SURE RELIEF VALVE - INSTALLATION)
INSTALLATION
(1) Install oil pump. (Refer to 9 - ENGINE/LUBRI-
CATION/OIL PUMP - ASSEMBLY)
(2) Install timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION) and oil pan (Refer to 9
- ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
INTAKE MANIFOLD
DESCRIPTION
The intake system is made up of an upper and
lower intake manifold. The upper intake manifold is
made of a composite for both the 3.3L engine and for
the 3.8L engine (Fig. 117). The lower intake manifold
is common between the two engines (Fig. 121). It also
provides coolant crossover between cylinder heads
and houses the coolant thermostat (Fig. 121).
The intake manifold utilizes a compact design with
very low restriction and outstanding flow balance.
This design allows the engine to perform with a wide
torque curve while increasing higher rpm horse-
power.
If, for some reason, the molded-in vacuum ports
break, the composite manifold can be salvaged. The
vacuum ports are designed to break at the shoulder,
if overloaded. Additional material in the shoulder
area provides sufficient stock to repair. For more
information and procedure, (Refer to 9 - ENGINE/
MANIFOLDS/INTAKE MANIFOLD - STANDARD
PROCEDURE). Also, if the special screws that attach
the MAP sensor, power steering reservoir, throttle
cable bracket, and the EGR tube become stripped, an
oversized screw is available to repair the stripped-out
condition. For more information and procedure,
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - STANDARD PROCEDURE)
Fig. 110 Measuring Clearance Between Rotors
1 - FEELER GAUGE
2 - INNER ROTOR
3 - OUTER ROTOR
Fig. 111 Measuring Clearance Over Rotors
1 - FEELER GAUGE
2 - STRAIGHT EDGE
Fig. 112 Oil Pressure Relief Valve
1 - RELIEF VALVE
2 - SPRING
3 - RETAINER CAP
9 - 144 ENGINE 3.3/3.8LRS
OIL PUMP (Continued)

DIAGNOSIS AND TESTING - INTAKE
MANIFOLD LEAKS
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
(1) Start the engine.
(2) Spray a small stream of water (Spray Bottle) at
the suspected leak area.
(3) If engine RPM'S change, the area of the sus-
pected leak has been found.
(4) Repair as required.
INTAKE MANIFOLD - UPPER
STANDARD PROCEDURE
STANDARD PROCEDURE - MANIFOLD
STRIPPED THREAD REPAIR
The composite upper intake manifold thread
bosses, if stripped out, can be repaired by utilizing a
repair screw available through Mopartparts. Repair
screws are available for the following manifold
attached components:
²MAP sensor
²Power steering reservoir
²EGR tube
²Throttle cable bracket
The repair screws require a unique tightening
torque specification from the original screw. Refer to
the following chart for specification.
DESCRIPTION TORQUE*
STRIP-OUT REPAIR SCREWS ONLY
MAP Sensor Repair
Screw4 N´m (35 in. lbs.)
Power Steering Reservoir
Repair Screw9 N´m (80 in. lbs.)
EGR Tube Attaching
Repair Screw9 N´m (80 in. lbs.)
Throttle Cable Bracket
Repair Screw9 N´m (80 in. lbs.)
*Install Slowly Using Hand Tools Only
STANDARD PROCEDURE - INTAKE MANIFOLD
VACUUM PORT REPAIR
The composite intake manifold vacuum ports can
be repaired. Although, if the manifold plenum cham-
ber is damaged or cracked, the manifold must be
replaced.
To repair a broken or damaged vacuum nipple
(port) on the composite intake manifold, perform the
following procedure:
PARTS REQUIRED TOOLS REQUIRED
´ Brass Nipple ± 1/49
O.D. x 1/89pipe thread
(LDP/Speed Control Port)´ Pipe Tap ± 1/89-18
NPT
´ Drill Bit ± 11/329
´ File/Sandpaper
´ Brass Nipple ± 1/29
O.D. x 1/49pipe thread
(Brake Booster Port)´ Pipe Tap ± 1/49-18
NPT
´ Drill Bit ± 7/169
´ File/Sandpaper
NOTE: While performing this procedure, avoid get-
ting the manifold material residue into the plenum
chamber.
(1) File or sand the remaining port back until a
flat surface is obtained (plane normal to nipple (port)
axis).
(2) Drill out the nipple (port) base using a 7/16º
(brake booster port) or 11/32º (LDP/speed control port
) drill bit (Fig. 113).
(3) Using a 1/4º±18 NPT (brake booster port) or
1/8º±18 NPT (LDP/speed control port ) pipe tap, cut
internal threads (Fig. 113). Use caution to start tap
in a axis same as original nipple.
(4) Apply MopartThread Sealant to threads of
repair nipple(s).
(5) Install repair nipple(s). Do not over torque
repair nipple(s).
REMOVAL - UPPER INTAKE MANIFOLD
(1) Disconnect battery negative cable.
(2) Disconnect inlet air temperature (IAT) sensor
electrical connector.
(3) Remove air inlet resonator to throttle body
hose assembly.
(4) Disconnect throttle and speed control cables
from throttle body (Refer to 14 - FUEL SYSTEM/
FUEL INJECTION/THROTTLE CONTROL CABLE -
REMOVAL).
(5) Disconnect make-up air hose support clip from
throttle cable bracket.
(6) Disconnect the automatic idle speed (AIS)
motor and throttle position sensor (TPS) wiring con-
nectors from throttle body.
RSENGINE 3.3/3.8L9 - 145
INTAKE MANIFOLD (Continued)

CAUTION: The special screws used for attaching
the EGR tube and power steering reservoir to the
manifold must be installed slowly using hand tools
only. This requirement is to prevent the melting of
material that causes stripped threads. If threads
become stripped, an oversize repair screw is avail-
able. For more information and procedure (Refer to
9 - ENGINE/MANIFOLDS/INTAKE MANIFOLD - STAN-
DARD PROCEDURE - MANIFOLD STRIPPED
THREAD REPAIR).
(7) Install the power steering reservoir (Fig. 115).
Tighten screws to manifold to 5.6 N´m (50 in. lbs.).
(8) Connect throttle and speed control cables to
throttle body (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/THROTTLE CONTROL CABLE -
INSTALLATION)
(9) Attach make up air hose clip into the hole in
the throttle cable bracket.
(10) Connect the wiring connectors to the throttle
position sensor (TPS) and Automatic Idle Speed (AIS)
motor.
(11) Install air cleaner and air inlet hose assembly.
(12) Connect the inlet air temperature (IAT) sen-
sor electrical connector.
(13) Connect battery negative cable.
INTAKE MANIFOLD - LOWER
REMOVAL - LOWER INTAKE MANIFOLD
(1) Perform fuel system pressure release procedure
(before attempting any repairs).(Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE)
(2) Drain the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
(3) Remove the upper intake manifold. (Refer to 9
- ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL)
(4) Remove the fuel line. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL LINES - STANDARD
PROCEDURE) (Refer to 14 - FUEL SYSTEM/FUEL
DELIVERY/QUICK CONNECT FITTING - STAN-
DARD PROCEDURE)
(5) Remove ignition coil and bracket (Fig. 119).
(6) Disconnect heater supply hose and engine cool-
ant temperature sensor (Fig. 120).
(7) Disconnect the fuel injector wire harness.
(8) Remove the fuel injectors and rail assembly
(Fig. 119).
(9) Remove radiator upper hose.
(10) Remove the intake manifold bolts.
(11) Remove lower intake manifold (Fig. 121).WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
(12) Remove intake manifold seal retainers screws
(Fig. 121). Remove intake manifold gasket.
(13) Inspect and clean manifold. (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSPECTION) (Refer to 9 - ENGINE/MANIFOLDS/
INTAKE MANIFOLD - CLEANING)
CLEANING
(1) Discard gasket(s).
(2) Clean all sealing surfaces.
INSPECTION
Check for:
²Damage and cracks of each section.
²Clogged water passages in end cross-overs (if
equipped).
Fig. 119 FUEL RAIL AND IGNITION COIL &
BRACKET
1 - FUEL RAIL
2 - BOLT - FUEL RAIL
3 - NUT - IGNITION COIL
4 - BOLT - IGNITION COIL
5 - IGNITION COIL
6 - BRACKET - IGNITION COIL
7 - STUD - IGNITION COIL
8 - SEPARATOR - SPARK PLUG CABLE
9 - BRACKET - SPARK PLUG CABLE SEPARATOR
10 - BOLT - SEPARATOR BRACKET
11 - BRACKET - SPARK PLUG CABLE SEPARATOR
9 - 148 ENGINE 3.3/3.8LRS
INTAKE MANIFOLD - UPPER (Continued)

(11) Fill the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
EXHAUST MANIFOLD - RIGHT
REMOVAL
(1) Disconnect battery negative cable.
(2) Remove the wiper module. (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL)
(3) Disconnect spark plug wires.
(4) Remove bolts fastening crossover pipe to
exhaust manifold (Fig. 124).
(5) Disconnect and remove the upstream oxygen
sensor (Fig. 127).(6) Remove the heat shield attaching screws (Fig.
127).
(7) Remove the upper heat shield (Fig. 127).
(8) Raise vehicle on hoist and remove drive belt
shield.
(9) Loosen the power steering pump support strut
lower bolt (Fig. 125).
(10) Disconnect downstream oxygen sensor connec-
tor.
(11) Disconnect catalytic converter pipe from
exhaust manifold (Fig. 126).
Fig. 123 LOWER MANIFOLD TIGHTENING
SEQUENCE
Fig. 124 CROSS-OVER PIPE
1 - CROSS-OVER PIPE
2 - BOLT
3 - GASKET
4 - FLAG NUT
Fig. 125 P/S PUMP STRUT
1 - BOLT - LOWER
2 - STRUT - P/S PUMP
3 - BOLT - UPPER
Fig. 126 Catalytic Converter to Exhaust Manifold
1 - FLAG NUT
2 - GASKET
3 - BOLT
4 - CATALYTIC CONVERTER
9 - 150 ENGINE 3.3/3.8LRS
INTAKE MANIFOLD - LOWER (Continued)

(17) Remove the water pump for cover removal
clearance. (Refer to 7 - COOLING/ENGINE/WATER
PUMP - REMOVAL)
(18) Remove the bolt attaching the power steering
pump support strut to the front cover (Fig. 137).
(19) Remove the timing chain cover fasteners.
Remove timing chain cover (Fig. 138).
INSTALLATION
(1) Be sure mating surfaces of chain case cover
and cylinder block are clean and free from burrs.
Crankshaft oil seal must be removed to insure cor-
rect oil pump engagement.
NOTE: DO NOT USE SEALER ON COVER GASKET
(2) Position new gasket on timing cover (Fig. 138).
Adhere new gasket to chain case cover, making sure
that the lower edge of the gasket is flush to 0.5 mm
(0.020 in.) passed the lower edge of the cover.
(3) Rotate crankshaft so that the oil pump drive
flats are in the vertical position.
(4) Position oil pump inner rotor so the mating
flats are in the same position as the crankshaft drive
flats (Fig. 138).
CAUTION: Make sure the oil pump is engaged on
the crankshaft correctly or severe damage may
result.
(5) Install timing cover (Fig. 138).
(6) Install timing chain cover bolts. Tighten M8
bolts to 27 N´m (20 ft. lbs.) and M10 bolts to 54 N´m
(40 ft. lbs.) (Fig. 139).
(7) Install crankshaft front oil seal. (Refer to 9 -
ENGINE/ENGINE BLOCK/CRANKSHAFT OIL
SEAL - FRONT - INSTALLATION)
(8) Install water pump and pulley. (Refer to 7 -
COOLING/ENGINE/WATER PUMP - INSTALLA-
TION)(9) Install crankshaft vibration damper. (Refer to 9
- ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
INSTALLATION)
(10) Install engine mount bracket (Fig. 136) and
tighten M10 to 54 N´m (40 ft. lbs.), M8 bolt to 28
N´m (21 ft. lb. lbs.).
(11) Install idler pulley on engine mount bracket
(Fig. 136).
(12) Install right side engine mount. (Refer to 9 -
ENGINE/ENGINE MOUNTING/RIGHT MOUNT -
INSTALLATION)
(13) Install camshaft position sensor (Refer to 8 -
ELECTRICAL/IGNITION CONTROL/CAMSHAFT
POSITION SENSOR - INSTALLATION).
(14) Connect the heater return hose at rear of tim-
ing chain cover (Fig. 134) or at water pump inlet
tube (if engine oil cooler equipped) (Fig. 135).
(15) Connect the radiator lower hose.
(16) Install A/C compressor.
(17) Install accessory drive belt. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION)
(18) Install oil pump pick-up tube with new
O-ring. Tighten attaching bolt to 28 N´m (250 in.
lbs.).
(19) Install oil pan. (Refer to 9 - ENGINE/LUBRI-
CATION/OIL PAN - INSTALLATION)
(20) Install inner splash shield and right front
wheel.
(21) Fill crankcase with engine oil to proper level.
(22) Fill cooling system. (Refer to 7 - COOLING -
STANDARD PROCEDURE)
(23) Connect negative cable to battery.
Fig. 137 Power Steering Pump Strut
1 - BOLT - LOWER
2 - STRUT - P/S PUMP
3 - BOLT - UPPER
Fig. 138 Timing Chain Cover and Gasket
1 - GASKET
2 - TIMING CHAIN COVER
RSENGINE 3.3/3.8L9 - 155
TIMING CHAIN COVER (Continued)

CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.
VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
COOLING SYSTEM TESTER METHOD
WARNING: WITH COOLING SYSTEM TESTER IN
PLACE, PRESSURE WILL BUILD UP FAST. EXCES-
SIVE PRESSURE BUILT UP, BY CONTINUOUS
ENGINE OPERATION, MUST BE RELEASED TO A
SAFE PRESSURE POINT. NEVER PERMIT PRES-
SURE TO EXCEED 138 kPa (20 psi).
Install Cooling System Tester 7700 or equivalent to
pressure cap neck. Start the engine and observe the
tester's pressure gauge. If gauge pulsates with every
power stroke of a cylinder a combustion pressure
leak is evident.
CHEMICAL TEST METHOD
Combustion leaks into the cooling system can also
be checked by using Bloc-Chek Kit C-3685-A or
equivalent. Perform test following the procedures
supplied with the tool kit.
REMOVAL - CYLINDER HEAD
(1) Drain the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
(2) Disconnect negative cable from battery.
(3) Remove upper and lower intake manifolds.
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - REMOVAL)
WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
(4) Remove the cylinder head covers. (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL)
(5) Remove the spark plugs from cylinder head.
(6) Remove the dipstick and tube (Fig. 2).
(7) Remove exhaust manifold(s). (Refer to 9 -
ENGINE/MANIFOLDS/EXHAUST MANIFOLD -
REMOVAL)
(8) Remove rocker arm and shaft assemblies.(Refer
to 9 - ENGINE/CYLINDER HEAD/ROCKER ARMS -REMOVAL) Remove push rods andmark positions
to ensure installation in original locations.
(9) Remove the eight head bolts from each cylinder
head and remove cylinder heads (Fig. 6).
CLEANING
To ensure engine gasket sealing, proper surface
preparation must be performed, especially with the
use of aluminum engine components and multi-layer
steel cylinder head gaskets.
NOTE: Multi-Layer Steel (MLS) head gaskets require
a scratch free sealing surface.
Remove all gasket material from cylinder head and
block (Refer to 9 - ENGINE - STANDARD PROCE-
DURE). Be careful not to gouge or scratch the alumi-
num head sealing surface.
Clean all engine oil passages.
INSPECTION
(1) Before cleaning, check for leaks, damage and
cracks.
(2) Clean cylinder head and oil passages.
(3) Check cylinder head for flatness (Fig. 3).
(4) Cylinder head must be flat within:
Fig. 2 DIPSTICK & TUBE
1 - DIPSTICK
2 - BOLT
3 - TUBE
RSENGINE 3.3/3.8L SUPPLEMENT9s-17
CYLINDER HEAD (Continued)

EXHAUST SYSTEM
TABLE OF CONTENTS
page page
EXHAUST SYSTEM
DESCRIPTION..........................1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - EXCESSIVE
EXHAUST SYSTEM NOISE...............2
DIAGNOSIS AND TESTING - EXHAUST
SYSTEM RESTRICTION CHECK...........2
INSPECTION...........................3
ADJUSTMENTS.........................3
SPECIFICATIONS
TORQUE.............................3
SPECIAL TOOLS
EXHAUST SYSTEM.....................4
CATALYTIC CONVERTER
DESCRIPTION..........................4
OPERATION............................4
REMOVAL.............................5INSPECTION...........................5
INSTALLATION..........................6
CROSS-OVER PIPE - 3.3/3.8L
REMOVAL.............................6
INSTALLATION..........................6
HEAT SHIELDS
DESCRIPTION..........................6
OPERATION............................7
REMOVAL.............................7
INSTALLATION..........................7
MUFFLER
REMOVAL.............................7
INSTALLATION..........................7
RESONATOR
REMOVAL.............................9
INSTALLATION..........................9
EXHAUST SYSTEM
DESCRIPTION
The exhaust system consists of a catalytic con-
verter, muffler, and a resonator with connecting pipes
in-between (Fig. 1). The system is serviced in two
sections; the catalytic converter and pipe, and the
muffler and resonator with connecting pipe. A band
clamp is used to connect the joint between the twocomponents. Three support hanger rods with rubber
isolators are used to support and isolate the exhaust
system. A flexible joint, integral to the catalytic con-
verter, allows for engine movement. On vehicles
equipped with AWD, an additional heat shield is
mounted to the catalytic converter. The exhaust sys-
tem is tuned for each vehicle/powertrain combination.
Fig. 1 Exhaust System - Typical (All Vehicles)
1 - CATALYTIC CONVERTER 4 - SUPPORT - RESONATOR
2 - BAND CLAMP 5 - RESONATOR
3 - SUPPORTS - MUFFLER 6 - MUFFLER
RSEXHAUST SYSTEM11-1

FUEL DELIVERY
DESCRIPTION
The front wheel drive car uses a plastic fuel tank
located rear center of the vehicle.
The Fuel Delivery System consists of: the following
items:
²Electric fuel pump module
²Fuel filter
²Tubes/lines/hoses
²Fuel injectors
The in-tank fuel pump module contains the fuel
pump. The pump is serviced as part of the fuel pump
module. Refer to Fuel Pump Module.
The fuel filter is replaceable only as part of the
fuel pump module.
OPERATION
The fuel system provides fuel pressure by an
in-tank pump module. The Powertrain Control Mod-
ule (PCM) controls the operation of the fuel system
by providing battery voltage to the fuel pump
through the fuel pump relay. The PCM requires only
three inputs and a good ground to operate the fuel
pump relay. The three inputs are:
²Ignition voltage
²Crankshaft Position (CKP) sensor
²Camshaft Position (CMP) sensor
DIAGNOSIS AND TESTING - FUEL DELIVERY
SYSTEM
(Refer to Appropriate Diagnostic Information)
STANDARD PROCEDURE
STANDARD PROCEDURE - FUEL SYSTEM
PRESSURE RELEASE PROCEDURE
(1) Remove Fuel Pump relay from Power Distribu-
tion Center (PDC). For location of relay, refer to label
on underside of PDC cover.
(2) Start and run engine until it stalls.
(3) Attempt restarting engine until it will no
longer run.
(4) Turn ignition key to OFF position.
(5) Return fuel pump relay to PDC.
(6) One or more Diagnostic Trouble Codes (DTC's)
may have been stored in PCM memory due to fuel
pump relay removal. The DRB IIItscan tool must be
used to erase a DTC.
STANDARD PROCEDURE - DRAINING FUEL
TANK
Two different procedures may be used to drain fuel
tank (lowering tank or using DRBIIItscan tool).The quickest draining procedure involves lowering
the fuel tank.
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
SERVICE VEHICLES IN WELL VENTILATED AREAS
AND AVOID IGNITION SOURCES. NEVER SMOKE
WHILE SERVICING THE VEHICLE. THIS MAY
RESULT IN PERSONAL INJURY OR DEATH.
As an alternative procedure, the electric fuel pump
may be activated allowing tank to be drained at fuel
rail connection. Refer to DRBIIItscan tool for fuel
pump activation procedures. Before disconnecting
fuel line at fuel rail, release fuel pressure. Refer to
the Fuel System Pressure Release Procedure in this
group for procedures. Disconnect the fuel line at the
fuel rail and remove the plastic retainer from the
fuel rail. Take plastic retainer and install it back into
the fuel line from body. Check the O-ring and make
sure that it is in place and not damaged. Attach end
of special test hose tool number 6539 at fuel line con-
nection from the body line. Position opposite end of
this hose tool to an approved gasoline draining sta-
tion. Activate fuel pump and drain tank until empty.
When done remove the special test hose tool number
6539 from the body line. Remove the plastic retainer
from the special test hose tool number 6539 and rein-
stall it into the fuel line from the body. Check the
O-ring and make sure that it is in place and not
damaged. Install the fuel line to the fuel rail.
If electric fuel pump is not operating, tank must be
lowered for fuel draining. Refer to following proce-
dures.
(1) Remove fuel filler cap.
(2) Perform the Fuel System Pressure Release pro-
cedure.
(3) Disconnect negative cable from battery.
(4) Raise vehicle and support.
(5) Certain models are equipped with a separate
grounding wire (strap) connecting the fuel fill tube
assembly to the body. Disconnect wire by removing
screw.
(6) Open fuel fill door and remove screws mount-
ing fuel filler tube assembly to body. Do not discon-
nect rubber fuel fill or vent hoses from tank at this
time.
(7) Place a transmission jack under center of fuel
tank. Apply a slight amount of pressure to fuel tank
with transmission jack.
(8) Remove fuel tank mounting straps.
(9)Lower the tank just enough so that the
filler tube fitting is the highest point of the fuel
tank.
(10) Remove filler tube from fuel tank. Tank will
be drained through this fitting.
14 - 2 FUEL DELIVERYRS

FUEL INJECTION
OPERATION
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 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.
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 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 theprimaryinputs that determine
injector pulse width.
OPERATION - 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 PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygensensor diagnostics (they are checked for shorted con-
ditions 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 oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum 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 35ÉF.
²If the coolant is over 35ÉF the PCM will wait 38
seconds.
²If the coolant is over 50ÉF the PCM will wait 15
seconds.
²If the coolant is over 167ÉF the PCM will wait 3
seconds.
(2) For other temperatures the PCM will interpo-
late 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:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition 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 operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
PCM determines basic fuel injector pulse width from
this input.
²The 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
14 - 18 FUEL INJECTIONRS