Rear control CHRYSLER VOYAGER 2005 Service Manual

(4) Install spark plugs.
(5) Install cylinder head cover. (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION)
ENGINE BLOCK
DESCRIPTION
The cast iron cylinder block is a two-piece assem-
bly, consisting of the cylinder block and bed plate
(Fig. 40). The bed plate incorporates the main bear-
ing caps and bolts to the cylinder block. This design
offers a much stronger lower end and increased cyl-
inder block rigidity. The rear oil seal retainer is inte-
gral with the block. The bed plate and block are
serviced as an assembly.
STANDARD PROCEDURE - CYLINDER BORE
HONING
(1) Used carefully, the cylinder bore resizing hone,
recommended tool C-823 or equivalent, equipped
with 220 grit stones, is the best tool for this honing
procedure. In addition to deglazing, it will reducetaper and out-of-round as well as removing light
scuffing, scoring or scratches. Usually a few strokes
will clean up a bore and maintain the required lim-
its.
(2) Deglazing of the cylinder walls may be done
using a cylinder surfacing hone, recommended tool
C-3501 or equivalent, equipped with 280 grit stones,
if the cylinder bore is straight and round. 20±60
strokes depending on the bore condition, will be suf-
ficient to provide a satisfactory surface. Use a light
honing oil.Do not use engine or transmission oil,
mineral spirits or kerosene.Inspect cylinder walls
after each 20 strokes.
(3) Honing should be done by moving the hone up
and down fast enough to get a cross-hatch pattern.
When hone marksintersectat 40-60 degrees, the
cross hatch angle is most satisfactory for proper seat-
ing of rings (Fig. 41).
(4) A controlled hone motor speed between
200±300 RPM is necessary to obtain the proper cross-
hatch angle. The number of up and down strokes per
minute can be regulated to get the desired 40±60
degree angle. Faster up and down strokes increase
the cross-hatch angle.
(5) After honing, it is necessary that the block be
cleaned again to remove all traces of abrasive.
Fig. 39 Rocker Arm
1 - TIP
2 - LASH ADJUSTER POCKET
3 - ROLLER
Fig. 40 Cylinder Block and Bed plate
1 - CYLINDER BLOCK
2 - BED PLATE
Fig. 41 Cylinder Bore Cross-Hatch Pattern
1 - CROSS-HATCH PATTERN
2 - 40ɱ60É
9 - 36 ENGINE 2.4LRS
ROCKER ARMS (Continued)

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.
78), all others are of molded rubber material.
FRONT MOUNT
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove the front engine mount through bolt
from the insulator (Fig. 79).
(3) Remove the engine front mount bolts and
remove the insulator assembly (Fig. 79).
(4) Remove the front mounting bracket from
engine, if necessary (Fig. 79).
INSTALLATION
(1) Install the front mount bracket to engine, if
removed (Fig. 79).
(2) Install the insulator mount assembly (Fig. 79).
(3) Install the front engine mount through bolt to
the insulator (Fig. 79).
(4) Lower the vehicle.
LEFT MOUNT
REMOVAL
(1) Raise the vehicle on hoist.
(2) Remove the left front wheel.
(3) Remove the left mount through bolt access
cover.
(4) Support the transaxle with a suitable jack.
(5) Remove the engine front mount through bolt to
allow left mount removal clearance (Fig. 79).
(6) Remove the left mount through frame rail bolt
(Fig. 80).
(7) Lower transaxle for access to horizontal bolts.
(8) Remove the horizontal bolts from the mount to
the transaxle (Fig. 81).
NOTE: To remove mount, additional lowering of
transaxle may be required.
(9) Remove left mount.
INSTALLATION
(1) Install left mount on transaxle (Fig. 81).
(2) Raise transaxle with jack until left mount is in
position.
(3) Install left mount through bolt (Fig. 80).
Fig. 78 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
Fig. 79 Front Mount and Bracket
1 - BRACKET - FRONT MOUNT
2 - NUT - 68 N´m (50 ft. lbs.)
3 - BOLT - 54 N´m (40 ft. lbs.)
4 - MOUNT - FRONT INSULATOR
5 - BOLT - 68 N´m (50 ft. lbs.)
6 - BOLT - 68 N´m (50 ft. lbs.)
7 - FRONT CROSSMEMBER
9 - 50 ENGINE 2.4LRS

CONDITION POSSIBLE CAUSES CORRECTION
OIL CONSUMPTION OR SPARK
PLUGS FOULED1. PCV system malfunction. 1. Check system and repair as
necessary. (Refer to 25 -
EMISSIONS CONTROL/
EVAPORATIVE EMISSIONS/PCV
VALVE - DIAGNOSIS AND
TESTING)
2. Worn, scuffed or broken rings. 2. Hone cylinder bores. Install new
rings.
3. Carbon in oil ring slots. 3. Install new rings.
4. Rings fitted too tightly in grooves. 4. Remove rings and check
grooves. If groove is not proper
width, replace piston.
5. Worn valve guide(s). 5. Replace cylinder head assembly.
6. Valve stem seal(s) worn or
damaged.6. Replace seal(s).
DIAGNOSIS AND TESTING - ENGINE OIL LEAK
INSPECTION
Begin with a thorough visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair as necessary.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24 km (15 miles), and
repeat inspection.
(5)If the oil leak source is not positively
identified at this time, proceed with the air leak
detection test method as follows:
²Disconnect the fresh air hose (make-up air) at
the cylinder head cover and plug or cap the outlet on
the cover.
²Remove the PCV valve hose from the cylinder
head cover. Cap or plug the PCV valve outlet on the
cover.
²Attach an air hose with pressure gauge and reg-
ulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.²Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provides the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
²If the leakage occurs at the crankshaft rear oil
seal area, refer to the section, Inspection for Rear
Seal Area Leak.
(6) If no leaks are detected, turn off the air supply.
Remove the air hose, all plugs, and caps. Install the
PCV valve and fresh air hose (make-up air). Proceed
to next step.
(7) Clean the oil off the suspect oil leak area using
a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.
NOTE: If oil leakage is observed at the dipstick tube
to block location; remove the tube, clean and reseal
using MoparTStud & Bearing Mount (press fit tube
applications only), and for O-ring style tubes,
remove tube and replace the O-ring seal.
INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
9 - 84 ENGINE 3.3/3.8LRS
ENGINE 3.3/3.8L (Continued)

(9) Raise vehicle.
(10) Attach wiring harness support clip to the
engine oil dipstick tube.
(11) Connect oil pressure switch electrical connec-
tor.
(12) Install the A/C compressor.
(13) Install the water pump pulley.
(14) Connect the radiator lower hose.
(15) Install the accessory drive belt and splash
shield (Refer to 7 - COOLING/ACCESSORY DRIVE/
DRIVE BELTS - INSTALLATION).(16) Connect the engine block heater electrical con-
nector (if equipped).
(17) Connect the knock sensor electrical connector
(3.8L only).
(18) Install the torque converter to flex plate bolts.
(19) Install the transaxle case cover (Fig. 8).
(20) Install the powertrain struts (Fig. 8).
(21) Install the engine rear mount bracket.
(22) Install the engine front mount and bracket
assembly.
(23)AWD equipped;Install the power transfer
unit (PTU) (Refer to 21 - TRANSMISSION/TRANS-
AXLE/POWER TRANSFER UNIT - INSTALLA-
TION).
(24) Install the axle shafts (Refer to 3 - DIFFER-
ENTIAL & DRIVELINE/HALF SHAFT - INSTALLA-
TION).
(25) Connect exhaust pipe to manifold (Fig. 7).
(26) Install crossmember cradle plate (Fig. 6).
(27) Lower vehicle.
(28) Connect transaxle shift linkage.
(29) Connect transaxle electrical connectors.
(30) Remove plugs from transmission cooler hoses
and install transaxle oil cooler line service splice kit.
Refer to instructions included with kit.
(31) Install transaxle dipstick tube and attach
electrical harness clip.
(32) Connect the A/C lines to compressor.
(33) Connect the A/C compressor electrical connec-
tor.
(34) Evacuate and recharge A/C system.
(35) Connect crankshaft and camshaft position
sensors.
(36) Connect the fuel injector electrical harness
connector and engage clip to support bracket.
(37) Connect engine coolant temperature (ECT)
sensor and ignition coil electrical connectors.
(38) Connect the ground strap to rear of cylinder
head.
(39) Install power steering reservoir.
(40) Engage wire harness clip to engine right side
mount.
(41) Connect the brake booster and speed control
vacuum hoses.
(42) Connect the vacuum hoses to the throttle
body.
(43) Connect the EGR transducer electrical connec-
tor (if equipped).
(44) Connect the TPS, IAC, and MAP sensor elec-
trical connectors.
(45) Connect throttle cables to throttle body.
(46) Install the radiator fans (Refer to 7 - COOL-
ING/ENGINE/RADIATOR FAN - INSTALLATION).
(47) Connect the radiator upper hose.
(48) Connect the heater hoses. Remove pinch-off
pliers from the rear heater hoses (if equipped).
Fig. 13 Right Mount to Engine
1 - BOLT
2 - MOUNT BRACKET
3 - ENGINE RIGHT MOUNT ASSEMBLY
Fig. 14 LEFT MOUNT TO FRAME BRACKET
1 - FRAME BRACKET
2 - FRAME RAIL - LEFT
3 - BOLT
4 - TRANSAXLE MOUNT
9 - 92 ENGINE 3.3/3.8LRS
ENGINE 3.3/3.8L (Continued)

CAMSHAFT & BEARINGS (IN
BLOCK)
DESCRIPTION
The nodular iron camshaft is mounted in the
engine block and supported with four steel backed
aluminum bearings (Fig. 49). A thrust plate, located
in front of the first bearing, is bolted to the block and
controls the camshaft end play (Fig. 49). To distin-
guish camshafts between the 3.3L and 3.8L engines,
a cast-in ring is located between the rear bearing
journal and rear lobe (Fig. 50). The 3.3L engine
application is as-cast only. The 3.8L engine applica-
tion the cast ring is machined off.
OPERATION
The camshaft is driven by the crankshaft through
a timing chain and sprockets. The camshaft has pre-
cisely machined (egg-shaped) lobes to provide accu-
rate valve timing and duration.
REMOVAL
(1) Remove the engine assembly from vehicle
(Refer to 9 - ENGINE - REMOVAL).
(2) Remove the cylinder heads (Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(3) Remove the timing chain and camshaft
sprocket (Refer to 9 - ENGINE/VALVE TIMING/TIM-
ING BELT/CHAIN AND SPROCKETS - REMOVAL).
(4) Remove the hydraulic lifters (Refer to 9 -
ENGINE/ENGINE BLOCK/HYDRAULIC LIFTERS
(CAM IN BLOCK) - REMOVAL). Identify each tappet
for reinstallation in original location.
(5) Remove camshaft thrust plate (Fig. 49).
(6) Install a long bolt into front of camshaft to
facilitate removal of the camshaft.
(7) Remove the camshaft (Fig. 49), being careful
not to damage cam bearings with the cam lobes.
NOTE: The camshaft bearings are serviced with the
engine block.
INSPECTION
(1) Check the cam lobes and bearing surfaces for
abnormal wear and damage (Fig. 51). Replace cam-
shaft as required.
NOTE: If camshaft is replaced due to lobe wear or
damage, always replace the lifters.
(2) Measure the lobe actual wear (unworn area -
wear zone = actual wear) (Fig. 51) and replace cam-
shaft if out of limit. Standard value is 0.0254 mm
(0.001 in.), wearlimitis 0.254 mm (0.010 in.).
INSTALLATION
(1) Lubricate camshaft lobes and camshaft bearing
journals with engine oil.
(2) Install a long bolt into the camshaft to assist in
the installation of the camshaft.
(3) Carefully install the camshaft in engine block.
(4) Install camshaft thrust plate and bolts (Fig.
49). Tighten to 12 N´m (105 in. lbs.) torque.
(5) Measure camshaft end play. (Refer to 9 -
ENGINE - SPECIFICATIONS) If not within specifi-
cations, replace thrust plate.
(6) Install the timing chain and sprockets. (Refer
to 9 - ENGINE/VALVE TIMING/TIMING BELT/
CHAIN AND SPROCKETS - INSTALLATION)
Fig. 49 CAMSHAFT AND BEARINGS
1 - CAMSHAFT
2 - THRUST PLATE
3 - BOLT
4 - CAMSHAFT BEARINGS (SERVICED WITH BLOCK)
Fig. 50 CAMSHAFT IDENTIFICATION
1 - CAMSHAFT - 3.3L ENGINE
2 - CAST-IN RING
3 - CAMSHAFT - 3.8L ENGINE
4 - MACHINED CAST-IN RING
9 - 118 ENGINE 3.3/3.8LRS

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.
87), 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. 88).
(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. 88).
(5) Remove the front mounting bracket, if neces-
sary (Fig. 88).
INSTALLATION
(1) Install the front mounting bracket, if removed
(Fig. 88).
(2) Install the front engine mount through bolt
from the insulator and front crossmember mounting
bracket (Fig. 88).
(3) Install the insulator assembly and mounting
screws (Fig. 88).
Fig. 87 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
9 - 134 ENGINE 3.3/3.8LRS

(9) Install crankshaft vibration damper. (Refer to 9
- ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
INSTALLATION)
(10) Install engine mount bracket (Fig. 137) 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. 137).
(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. 135) or at water pump inlet
tube (if engine oil cooler equipped) (Fig. 136).
(15) Connect the radiator lower hose.
(16) Install A/C compressor.
Fig. 139 Timing Chain Cover and Gasket
1 - GASKET
2 - TIMING CHAIN COVER
Fig. 140 TIMING CHAIN COVER BOLT LOCATIONS
1 - BOLT - M8 x 1.25 x 95 4 - BOLT - M8 x 1.25 x 80
2 - BOLT - M10 x 1.5 x 100 5 - BOLT - M8 x 1.25 x 45
3 - BOLT - M10 x 1.5 x 85
9 - 158 ENGINE 3.3/3.8LRS
TIMING CHAIN COVER (Continued)

SPECIFICATIONS - TORQUE
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Front Cradle Crossmember to Fram Rail Attaching Bolts (4) 163 120 Ð
Reinforcement Plate to Crossmember Attaching Bolt Size M14 (9) 153 113 Ð
Reinforcement Plate to Crossmember Attaching Bolt Size M12 (1) 106 78 Ð
Reinforcement Plate to Crossmember Attaching Bolt Size M10 (4) 61 45 Ð
Rear Engine Mount to Crossmember Attaching Through Bolt 68 50 Ð
Radiator Support Crossmember Attaching Bolts 51 38 Ð
FRONT CRADLE
CROSSMEMBER
DESCRIPTION
DESCRIPTION - FRONT CRADLE
CROSSMEMBER
This vehicle uses a one piece cast aluminum cradle
for the front cradle crossmember. The cradle cross-
member is used as the attaching points for the lower
control arms, stabilizer bar and steering gear. The
cradle also has the power steering hoses and the
chassis brake tubes attached to it.
WARNING: If a threaded hole in the suspension cra-
dle needs to be repaired, only use the type of
thread insert and installation procedure specified
for this application.
The threaded holes in the front cradle crossmem-
ber that are used for attachment of the lower control
arm rear bushing retainer, power steering hose and
chassis brake tubes can be repaired. The repair is
done by the installation of a Heli-Coiltthread insert
which has been specifically developed for this appli-
cation. Refer to the Mopar Parts Catalog for the spec-
ified Heli-Coiltthread insert to be used for this
application. The procedure for installing the Heli-
Coiltthread insert is detailed in the Service Proce-
dures section in this group of the service manual.
DESCRIPTION - FRONT CRADLE
CROSSMEMBER THREAD REPAIR
WARNING: When performing this procedure use
only the thread inserts which are specified in the
Mopar Parts Catalog for this repair procedure.
These thread inserts have been specifically devel-
oped for this application and use of other types of
thread inserts can result in an inferior long term
repair.The threaded holes in the front cradle crossmem-
ber, if damaged, can repaired by installing a Heli-
Coiltthread insert.
The threaded holes that are repairable using the
thread insert, are the lower control arm rear bushing
retainer mounting bolt holes, routing bracket attach-
ing locations for the power steering hoses, and brake
hose attachment holes.
This repair procedure now allows the threaded
holes in the cradle crossmember to be repaired, elim-
inating the need to replace the cradle crossmember if
damage occurs to one of the threaded holes.
The thread inserts for this application are specified
by part number in the Mopar Parts Catalog.Do not
use a substitute thread insert.
The specific tools and equipment required to install
the thread insert are listed below. Refer to the
instructions included with the thread insert for the
detailed procedure used for the installation of the
thread insert.
NOTE: The thread inserts for this application are for
the repair of M8x1.25 and M10x1.5 threads. Be sure
the correct tools are used for the required thread
insert size.
TOOL REQUIREMENT FOR M8x1.25 Thread
²8.3mm (5/16 in.) Drill Bit
²120É Countersink
²Heli-CoiltTap #4863-8
²Heli-CoiltGage #4624-8
²Heli-CoiltHand Inserting Tool 7751-8
²Needle Nose Pliers ± For Removal Of Thread
Insert Driving Tang
TOOL REQUIREMENT FOR M10x1.5 Thread
²10.5mm (25/64 in.) Drill Bit
²120É Countersink
²Heli-CoiltTap #4863-10
²Heli-CoiltGage #4624-10
²Heli-CoiltHand Inserting Tool 7751-10
²Needle Nose Pliers ± For Removal Of Thread
Insert Driving Tang
13 - 14 FRAME & BUMPERSRS
FRAME (Continued)

FUEL DELIVERY
DESCRIPTION
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.
DESCRIPTION - FFV REPLACEMENT PARTS
Many components in a Flexible Fuel Vehicle (FFV)
are designed to be compatible with ethanol. Always
be sure that the vehicle is serviced with correct etha-
nol compatible parts.
CAUTION: Replacing fuel system components with
non-ethanol compatible components can damage
your vehicle and may void the warranty.
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.
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 - 22 FUEL INJECTIONRS