engine coolant CHRYSLER CARAVAN 2003 Manual PDF

Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1,379
kPa (200 psi) maximum, with 552 kPa (80 psi) rec-
ommended.
Perform the test procedures on each cylinder
according to the tester manufacturer's instructions.
While testing, listen for pressurized air escaping
through the throttle body, tailpipe and oil filler cap
opening. Check for bubbles in the coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage per cylinder.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder.
STANDARD PROCEDURE
STANDARD PROCEDURE - MEASURING
BEARING CLEARANCE USING PLASTIGAGE
Engine crankshaft bearing clearances can be deter-
mined by use of Plastigage or equivalent. The follow-
ing is the recommended procedure for the use of
Plastigage:
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire
width of the bearing shell in the cap approximately
6.35 mm (1/4 in.) off center and away from the oil
holes (Fig. 3). (In addition, suspected areas can be
checked by placing the Plastigage in the suspected
area). Torque the bearing cap bolts of the bearing
being checked to the proper specifications.
(3) Remove the bearing cap and compare the
width of the flattened Plastigage with the metric
scale provided on the package. Locate the band clos-est to the same width. This band shows the amount
of clearance in thousandths of a millimeter. Differ-
ences in readings between the ends indicate the
amount of taper present. Record all readings taken.
Compare clearance measurements to specs found in
engine specifications (Refer to 9 - ENGINE - SPECI-
FICATIONS).Plastigage generally is accompa-
nied by two scales. One scale is in inches, the
other is a metric scale.
NOTE: Plastigage is available in a variety of clear-
ance ranges. Use the most appropriate range for
the specifications you are checking.
(4) Install the proper crankshaft bearings to
achieve the specified bearing clearances.
STANDARD PROCEDURE - FORM-IN-PLACE
GASKETS AND SEALERS
There are numerous places where form-in-place
gaskets are used on the engine. Care must be taken
when applying form-in-place gaskets to assure
obtaining the desired results.Do not use form-in-
place gasket material unless specified.Bead size,
continuity, and location are of great importance. Too
thin a bead can result in leakage while too much can
result in spill-over which can break off and obstruct
fluid feed lines. A continuous bead of the proper
width is essential to obtain a leak-free gasket.
There are numerous types of form-in-place gasket
materials that are used in the engine area. Mopart
Engine RTV GEN II, MopartATF-RTV, and Mopart
Gasket Maker gasket materials, each have different
properties and can not be used in place of the other.
MOPARtENGINE RTV GEN IIis used to seal
components exposed to engine oil. This material is a
specially designed black silicone rubber RTV that
retains adhesion and sealing properties when
exposed to engine oil. Moisture in the air causes the
material to cure. This material is available in three
ounce tubes and has a shelf life of one year. After one
year this material will not properly cure. Always
inspect the package for the expiration date before
use.
MOPARtATF RTVis a specifically designed
black silicone rubber RTV that retains adhesion and
sealing properties to seal components exposed to
automatic transmission fluid, engine coolants, and
moisture. This material is available in three ounce
tubes and has a shelf life of one year. After one year
this material will not properly cure. Always inspect
the package for the expiration date before use.
MOPARtGASKET MAKERis an anaerobic type
gasket material. The material cures in the absence of
air when squeezed between two metallic surfaces. It
will not cure if left in the uncovered tube. The
Fig. 3 Plastigage Placed in Lower ShellÐTypical
1 - PLASTIGAGE
9 - 84 ENGINE 3.3/3.8LRS
ENGINE 3.3/3.8L (Continued)
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anaerobic material is for use between two machined
surfaces. Do not use on flexible metal flanges.
MOPARtBED PLATE SEALANTis a unique
(green-in-color) anaerobic type gasket material that
is specially made to seal the area between the bed-
plate and cylinder block without disturbing the bear-
ing clearance or alignment of these components. The
material cures slowly in the absence of air when
torqued between two metallic surfaces, and will rap-
idly cure when heat is applied.
MOPARtGASKET SEALANTis a slow drying,
permanently soft sealer. This material is recom-
mended for sealing threaded fittings and gaskets
against leakage of oil and coolant. Can be used on
threaded and machined parts under all tempera-
tures. This material is used on engines with multi-
layer steel (MLS) cylinder head gaskets. This
material also will prevent corrosion. MopartGasket
Sealant is available in a 13 oz. aerosol can or 4oz./16
oz. can w/applicator.
SEALER APPLICATION
MopartGasket Maker material should be applied
sparingly 1 mm (0.040 in.) diameter or less of sealant
to one gasket surface. Be certain the material sur-
rounds each mounting hole. Excess material can eas-
ily be wiped off. Components should be torqued in
place within 15 minutes. The use of a locating dowel
is recommended during assembly to prevent smear-
ing material off the location.
MopartEngine RTV GEN II or ATF RTV gasket
material should be applied in a continuous bead
approximately 3 mm (0.120 in.) in diameter. All
mounting holes must be circled. For corner sealing, a
3.17 or 6.35 mm (1/8 or 1/4 in.) drop is placed in the
center of the gasket contact area. Uncured sealant
may be removed with a shop towel. Components
should be torqued in place while the sealant is still
wet to the touch (within 10 minutes). The usage of a
locating dowel is recommended during assembly to
prevent smearing material off the location.
MopartGasket Sealant in an aerosol can should be
applied using a thin, even coat sprayed completely
over both surfaces to be joined, and both sides of a
gasket. Then proceed with assembly. Material in a
can w/applicator can be brushed on evenly over the
sealing surfaces. Material in an aerosol can should be
used on engines with multi-layer steel gaskets.
STANDARD PROCEDURE - ENGINE GASKET
SURFACE PREPARATION
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.Neveruse the following to clean gasket surfaces:
²Metal scraper
²Abrasive pad or paper to clean cylinder block
and head
²High speed power tool with an abrasive pad or a
wire brush (Fig. 4)
NOTE: Multi-Layer Steel (MLS) head gaskets require
a scratch free sealing surface.
Only use the following for cleaning gasket surfaces:
²Solvent or a commercially available gasket
remover
²Plastic or wood scraper (Fig. 4)
²Drill motor with 3M RolocŸ Bristle Disc (white
or yellow) (Fig. 4)
CAUTION: Excessive pressure or high RPM (beyond
the recommended speed), can damage the sealing
surfaces. The mild (white, 120 grit) bristle disc is
recommended. If necessary, the medium (yellow, 80
grit) bristle disc may be used on cast iron surfaces
with care.
STANDARD PROCEDURE - HYDROSTATIC
LOCKED ENGINE
When an engine is suspected to be hydrostatically
locked, regardless of what caused the problem, the
following steps should be used.
CAUTION: DO NOT use starter motor to rotate the
engine, severe damage may occur.
Fig. 4 Proper Tool Usage For Surface Preparation
1 - ABRASIVE PAD
2 - 3M ROLOCŸ BRISTLE DISC
3 - PLASTIC/WOOD SCRAPER
RSENGINE 3.3/3.8L9-85
ENGINE 3.3/3.8L (Continued)
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(11) Disconnect the throttle cables from the throt-
tle body.
(12) Disconnect the MAP, IAC, and TPS electrical
connectors.
(13) Disconnect the EGR transducer electrical con-
nector (if equipped).
(14) Disconnect the vacuum hoses from throttle
body.
(15) Disconnect the brake booster and speed con-
trol vacuum hoses.
(16) Disengage wire harness clip from the right
side engine mount.
(17) Remove the power steering reservoir from
mounting position and set aside.Do notdisconnect
hose.
(18) Disconnect ground strap from rear of cylinder
head.
(19) Disconnect engine coolant temperature (ECT)
sensor and ignition coil electrical connectors.
(20) Disconnect the fuel injector electrical harness
connector and disengage clip from support bracket.
(21) Disconnect camshaft and crankshaft position
sensor electrical connectors.
(22) Evacuate air conditioning system. Refer to 24
- HEATING & AIR CONDITIONING.
(23) Disconnect A/C compressor electrical connec-
tor.
(24) Disconnect the A/C lines from compressor.
Cover and seal all openings of hoses and compressor.
(25) Remove the radiator upper hose.
(26) Disengage electrical harness clip at transaxle
dipstick tube.
(27) Remove transaxle dipstick tube. Seal opening
using a suitable plug.
NOTE: When the transaxle cooler lines are removed
from the rolled-groove type fittings at the transaxle,
damage to the inner wall of the hose will occur. To
prevent prevent potential leakage, the cooler hoses
must be cut off flush at the transaxle fitting, and a
service cooler hose splice kit must be installed
upon reassembly.
(28) Using a blade or suitable hose cutter, cut
transaxle oil cooler lines off flush with fittings. Plug
cooler lines and fittings to prevent debris from enter-
ing transaxle or cooler circuit. A service splice kit will
be installed upon reassembly.
(29) Disconnect transaxle shift linkage and electri-
cal connectors.
(30)
Raise vehicle on hoist and drain the engine oil.
(31) Remove the axle shafts. (Refer to 3 - DIFFER-
ENTIAL & DRIVELINE/HALF SHAFT - REMOVAL)
(32) Remove crossmember cradle plate (Fig. 6).
(33)AWD equipped:Remove the power transfer
unit (PTU) (Refer to 21 - TRANSMISSION/TRANS-
AXLE/POWER TRANSFER UNIT - REMOVAL).(34) Disconnect exhaust pipe from the manifold
(Fig. 7).
(35) Remove front engine mount and bracket as an
assembly.
(36) Remove the engine rear mount bracket.
(37) Remove the engine to transaxle struts (Fig. 8).
(38) Remove transaxle case cover (Fig. 8).
(39) Remove flex plate to torque converter bolts.
Mark torque converter to flex plate for orientation for
reassembly.
(40) Remove the power steering pressure hose sup-
port clip attaching bolt.
Fig. 6 Crossmember Cradle Plate
1 - CRADLE PLATE
Fig. 7 Catalytic Converter to Exhaust Manifold
1 - FLAG NUT
2 - GASKET
3 - BOLT
4 - CATALYTIC CONVERTER
RSENGINE 3.3/3.8L9-87
ENGINE 3.3/3.8L (Continued)
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(8) Install the generator and wiring harness (Refer
to 8 - ELECTRICAL/CHARGING/GENERATOR -
INSTALLATION).
(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).
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 - 90 ENGINE 3.3/3.8LRS
ENGINE 3.3/3.8L (Continued)
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AIR CLEANER HOUSING
REMOVAL
(1) Disconnect the negative battery cable.
(2) Disconnect the inlet air temperature sensor
(Fig. 16).
(3) Remove the inlet hose to throttle body.
(4) Remove the bolt for air box at upper radiator
cross member.
(5) Pull air box up and off over the single locating
pin.
(6) Remove air box from vehicle
INSTALLATION
(1) Install air box into vehicle and onto the locat-
ing pin.
(2) Install bolt to hold air box to the upper radia-
tor cross member.
(3) Install the inlet hose to the throttle body.
(4) Connect the inlet air temperature sensor (Fig.
16).
(5) Connect the negative battery cable.
CYLINDER HEAD
DESCRIPTION
The aluminum cylinder heads (Fig. 17) are
designed to create high flow combustion chambers to
improve performance, while minimizing the change
to the burn rate in the chamber. The cylinder head
incorporates the combustion chamber. Two valves
per-cylinder are used with inserted valve seats and
guides. A multi-layer steel (MLS) type gasket is used
between the cylinder head and engine block.
DIAGNOSIS AND TESTINGÐCYLINDER HEAD
GASKET
A cylinder head gasket leak can be located between
adjacent cylinders or between a cylinder and the
adjacent water jacket.
Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
²Loss of engine power
²Engine misfiring
²Poor fuel economy
Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
²Engine overheating
²Loss of coolant
²Excessive steam (white smoke) emitting from
exhaust
²Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test (Refer
to 9 - ENGINE - DIAGNOSIS AND TESTING). An
engine cylinder head gasket leaking between adja-
cent cylinders will result in approximately a 50±70%
reduction in compression pressure.
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.
Fig. 16 Inlet Air Temperature Sensor
RSENGINE 3.3/3.8L9-99
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OIL COOLER & LINES
DESCRIPTION
An engine oil cooler is used on 3.3/3.8L engines
(Heavy Duty Cooling Only) (Fig. 98). The cooler is a
coolant-to-oil type and mounted between the oil filter
and engine block.
OPERATION
Engine oil travels from the oil filter and into the
oil cooler. Engine oil then exits the cooler into the
main gallery. Engine coolant flows into the cooler
from the heater return tube and exits into the water
pump inlet.
REMOVAL
(1) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE - COOLING SYSTEM
DRAINING).
(2) Disconnect oil cooler inlet and outlet hoses
(Fig. 97).
(3) Remove oil filter.
(4) Remove oil cooler attachment fitting (Fig. 98).
(5) Remove oil cooler.
INSTALLATION
(1) Lubricate seal and position oil cooler to connec-
tor fitting on oil filter adapter (Fig. 98).NOTE: Position the flat side of oil cooler parallel to
oil pan rail.
(2) Install oil cooler attachment fitting and tighten
to 27 N´m (20 ft. lbs.) (Fig. 98).
(3) Install oil filter.
(4) Connect oil cooler inlet and outlet hoses (Fig.
97).
Fig. 96 Engine Oil Level Dipstick and Fill Locations
1 - COOLANT RECOVERY CONTAINER 3 - ENGINE OIL LEVEL DIPSTICK
2 - ENGINE OIL FILL CAP 4 - RADIATOR PRESSURE CAP
Fig. 97 Engine Oil Cooler Hoses
1 - OIL COOLER INLET TUBE
2 - INLET HOSE
3 - OIL COOLER OUTLET TUBE
4 - OUTLET HOSE
5 - WATER PUMP INLET TUBE
9 - 138 ENGINE 3.3/3.8LRS
OIL (Continued)
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(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)
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²Check for cylinder head mounting surface distor-
tion using a straightedge and thickness gauge. (Refer
to 9 - ENGINE/CYLINDER HEAD - INSPECTION)
INSTALLATION - LOWER INTAKE MANIFOLD
(1) Place a bead (approximately 1/4 in. diameter)
of MopartEngine RTV GEN II onto each of thefour
manifold to cylinder head gasket corners (Fig. 122).
(2) Carefully install the new intake manifold gas-
ket (Fig. 121). Tighten end seal retainer screws to 12
N´m (105 in. lbs.).
(3) Install lower intake manifold (Fig. 121). Install
the 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. 123). Then torque again to 22 N´m
(200 in. lbs.). After intake manifold is in place,
inspect to make sure seals are in place.
(4) Install the fuel injectors and rail assembly.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/
FUEL RAIL - INSTALLATION)
(5) Connect fuel injector electrical harness.
(6) Connect the engine coolant temperature sensor
(Fig. 120).
(7) Connect the heater supply (Fig. 120) and radi-
ator upper hoses to manifold.
(8) Connect the fuel line. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/QUICK CONNECT FIT-
TING - STANDARD PROCEDURE)(9) Install the upper intake manifold. (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION)
(10) Connect negative battery cable.
Fig. 120 ECT SENSOR & HEATER SUPPLY
1 - ENGINE COOLANT TEMPERATURE SENSOR
2 - CONNECTOR - ENGINE COOLANT SENSOR
3 - FITTING - HEATER SUPPLY
Fig. 121 INTAKE MANIFOLD - LOWER
1 - INTAKE MANIFOLD - LOWER
2 - BOLT - GASKET END SEAL RETAINER
3 - GASKET
4 - BOLT - LOWER INTAKE MANIFOLD
Fig. 122 Intake Manifold Gasket Sealing
1 - SEALER LOCATIONS
RSENGINE 3.3/3.8L9 - 149
INTAKE MANIFOLD - LOWER (Continued)
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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
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1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
ENGINE START-UP MODE
This is an OPEN LOOP mode. If the vehicle is in
park or neutral (automatic transaxles) or the clutch
pedal is depressed (manual transaxles) the ignition
switch energizes the starter relay when the engine is
not running. The following actions occur when the
starter motor is engaged.
²If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the Auto Shutdown (ASD) relay and fuel pump relay.
If the PCM does not receive both signals within
approximately one second, it will not energize the
ASD relay and fuel pump relay. The ASD and fuel
pump relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil, (EGR solenoid and PCV
heater if equipped) and heated oxygen sensors.
²The PCM energizes the injectors (on the 69É
degree falling edge) for a calculated pulse width until
it determines crankshaft position from the camshaft
position sensor and crankshaft position sensor sig-
nals. The PCM determines crankshaft position within
1 engine revolution.
²After determining crankshaft position, the PCM
begins energizing the injectors in sequence. It adjusts
injector pulse width and controls injector synchroni-
zation by turning the individual ground paths to the
injectors On and Off.
²When the engine idles within  64 RPM of its
target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode.
Once the ASD and fuel pump relays have been
energized, the PCM determines injector pulse width
based on the following:
²MAP
²Engine RPM
²Battery voltage
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)
²Throttle position
²The number of engine revolutions since cranking
was initiated
During Start-up the PCM maintains ignition tim-
ing at 9É BTDC.
ENGINE WARM-UP MODE
This is an OPEN LOOP mode. The following inputs
are received by the PCM:
²Manifold Absolute Pressure (MAP)
²Crankshaft position (engine speed)
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)²Camshaft position
²Knock sensor
²Throttle position
²A/C switch status
²Battery voltage
²Vehicle speed
²Speed control
²O2 sensors
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
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising or idle
the following inputs are received by the PCM:
²Manifold absolute pressure
²Crankshaft position (engine speed)
²Inlet/Intake air temperature
²Engine coolant temperature
²Camshaft position
²Knock sensor
²Throttle position
²Exhaust gas oxygen content (O2 sensors)
²A/C switch status
²Battery voltage
²Vehicle speed
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 (measured
by the upstream and downstream heated oxygen sen-
sor).
The PCM monitors for engine misfire. During
active misfire and depending on the severity, the
PCM either continuously illuminates or flashes the
malfunction indicator lamp (Check Engine light on
instrument panel). Also, the PCM stores an engine
misfire DTC in memory, if 2nd trip with fault.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
²Fuel system monitor
²EGR monitor (if equipped)
²Purge system monitor
²Catalyst efficiency monitor
²All inputs monitored for proper voltage range,
rationality.
RSFUEL INJECTION14-19
FUEL INJECTION (Continued)
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