coolant temperature CHRYSLER CARAVAN 2002 Repair Manual

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.
OPERATION
The cylinder head closes the combustion chamber,
allowing the pistons to compress the fuel/air mixture
for ignition. The valves are actuated by the lobe pro-
files on the camshaft to open and close at specified
duration to either allow clean air in the combustion
chamber or the exhaust gases out; depending on the
stroke of the engine.
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.
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.
9 - 100 ENGINE 3.3/3.8LRS
AIR CLEANER HOUSING (Continued)
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(6) Connect the engine coolant temperature sensor
(Fig. 126).
(7) Connect the heater supply (Fig. 126) 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.
(11) Fill the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
Fig. 126 ECT SENSOR & HEATER SUPPLY
1 - ENGINE COOLANT TEMPERATURE SENSOR
2 - CONNECTOR - ENGINE COOLANT SENSOR
3 - FITTING - HEATER SUPPLY
Fig. 127 INTAKE MANIFOLD - LOWER
1 - INTAKE MANIFOLD - LOWER
2 - BOLT - GASKET END SEAL RETAINER
3 - GASKET
4 - BOLT - LOWER INTAKE MANIFOLD
Fig. 128 Intake Manifold Gasket Sealing
1 - SEALER LOCATIONS
RSENGINE 3.3/3.8L9 - 151
INTAKE MANIFOLD - LOWER (Continued)
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INSTALLATION
INSTALLATION - 2.5L TURBO DIESEL ENGINE
(1) Reassembly engine and transmission assembly
and install on engine cradle.
(2) Position engine and cradle assembly under
vehicle.
(3) Slowly lower the vehicle down over the engine
and cradle assembly.
(4) Install right engine mount bolts. Torque to
54N´m (40 ft. lbs.)
(5) Install left engine mount through bolt. Torque
to 75N´m (55 ft. lbs.)
(6) Raise vehicle and engine from engine cradle.
(7) Attach front engine mount bracket to lower
radiator support. Torque to 54N´m (40 ft. lbs.)
(8) Connect cabin heater coolant hose.
(9) Connect exhaust pipe to the turbocharger
downpipe flange. Torque to 28 N´m (250 in. lbs.)
(10) Connect reverse lamp electrical connector at
transmission.
(11) Connect both shifter cables (Refer to 21 -
TRANSMISSION/TRANSAXLE/MANUAL/GEAR
SHIFT CABLE - INSTALLATION).
(12) Connect the clutch slave cylinder quick dis-
connect connector (RHD only)(Refer to 6 - CLUTCH/
SLAVE CYLINDER - INSTALLATION).
(13) Install engine harness into bracket on trans-
mission.
(14) Lower vehicle.
(15) Connect fuel supply and return lines.
(16) Connect A/C lines to A/C compressor. Torque
to 23N´m (17 ft. lbs.)
(17) Route engine wiring harnes to proper location.
(18) Connect engine harness ground cables to
engine block
(19) Connect starter solenoid electrical connector
and battery feed wire to starter. Torque to 10N´m (90
in. lbs.)
(20) Connect A/C compressor, injection pump, glow
plugs, and coolant temperature sensor electrical con-
nectors.
(21) Connect generator electrical connector. Torque
to 9N´m (75 in. lbs.)
(22) Connect the fuel injector, fuel pressure sensor,
boost pressure/intake air temp sensor, cam sensor,
and egr solenoid electrical connectors (Fig. 8).
(23) Connect egr solenoid vacuum supply line to
brake boost vacuum supply line.(24) Connect brake booster vacuum supply line.
(25) Connect heater core return hose to coolant
pipe.
(26) Connect lower radiator hose to engine (Fig. 7).
(27) Install charger air cooler inlet hose (Fig. 6).
(28) Install charge air cooler outlet hose (Fig. 6).
(29) Connect upper radiator hose to engine (Fig.
7).
(30) Install battery shield.
(31) Install coolant reserve pressure container
(Refer to 7 - COOLING/ENGINE/COOLANT RECOV-
ERY PRESS CONTAINER - INSTALLATION).
(32) Install power steering reservoir and bracket
(Fig. 4).
(33) Raise vehicle
(34) Connect oil pressure sensor, oil temperature
sensor, engine speed sensor, and vehicle speed sensor
electrical connector (Fig. 9).
(35) Install suspension cradle in vehicle (Refer to
13 - FRAME & BUMPERS/FRAME/ENGINE CRA-
DLE CROSSMEMBER - INSTALLATION).
(36) Install both axle shaft assemblies (Refer to 3 -
DIFFERENTIAL & DRIVELINE/HALF SHAFT -
INSTALLATION).
(37) Connect the power steering supply, pressure,
and return lines to power steering pump (Fig. 4).
(38) Install the power steering line brackets on oil
pan (Fig. 4).
(39) Install lower splash shield and side panels.
(40) Install both front wheel and tire assemblies.
(41) Lower vehicle.
(42) Install air cleaner housing, MAF sensor, and
air intake tube assembly (Fig. 3).
(43) Refill transmission to proper level (Refer to 21
- TRANSMISSION/TRANSAXLE/MANUAL/FLUID -
STANDARD PROCEDURE).
(44) Refill engine coolant (Refer to 7 - COOLING/
ENGINE/COOLANT - STANDARD PROCEDURE).
(45) Recharge A/C system (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING/REFRIGER-
ANT - STANDARD PROCEDURE) .
(46) Install engine cover (Refer to 9 - ENGINE -
INSTALLATION) (Fig. 2).
(47) Connect negative battery cable.
INSTALLATION - ENGINE COVER
(1) Install engine cover on engine.
(2) Install the engine cover mounting bolts (Fig.
10).
RGENGINE9a-7
ENGINE 2.5L TURBO DIESEL (Continued)
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(23) Remove cylinder head assembly from engine
block (Fig. 18).
CLEANING
Thoroughly clean the engine cylinder head and cyl-
inder block mating surfaces. Clean the intake and
exhaust manifold and engine cylinder head mating
surfaces. Remove all gasket material and carbon.
Check to ensure that no coolant or foreign material
has fallen into the tappet bore area.
Remove the carbon deposits from the combustion
chambers and top of the pistons.
INSPECTION
Use a straightedge and feeler gauge to check the
flatness of the engine cylinder head and block mating
surfaces.
The minimum cylinder head thickness is 89.95mm
(3.541 in.).
INSTALLATION
CAUTION: Piston protrusion must be measured to
determine cylinder head gasket thickness if one or
more cylinder liners have been replaced (Refer to 9
- ENGINE/CYLINDER HEAD - STANDARD PROCE-
DURE).
NOTE: If cylinder liner(s) have not been removed,
the same thickness head gasket that was removed
can be used.
(1) Clean and inspect gasket mating surfaces.
(2) Position correct head gasket on engine block.
(3) Place cylinder head on engine block (Fig. 18).
CAUTION: New cylinder head bolts must be used.
(4) Tighten cylinder head bolts following procedure
below.
Cylinder Head Bolt Torquing Procedure
(1) Lubricate cylinder head bolts with engine oil.
(2) Torque bolts to 30N´m in numerical starting
with bolt #1 (Fig. 19).
(3) Tighten all bolts an additional 75É, starting
with bolt #4 then 5-6-7-8-9-10-1-2-3 (Fig. 19).
(4) Tighten all bolts an additional 50É in numerical
order starting with bolt #11 then 12-13-14-15-16-
17-18 (Fig. 19).
(5) Without loosening any bolts tighten all bolts an
additional 75É in the following seguence: 4-5-6-7-8-9-
10-1-2-3-11-12-13-14-15-16-17-18.
Fig. 18 CYLINDER HEAD ASSEMBLY
1 - VALVE SPRING
2 - CYLINDER HEAD BOLT
3 - GLOW PLUG
4 - COOLANT TEMPERATURE SENSOR
5 - CYLINDER HEAD ALIGNMENT DOWEL
6 - CYLINDER BLOCK
7 - CYLINDER LINER
8 - ENGINE BLOCK DECK
9 - CYLINDER HEAD GASKET
10 - CYLINDER HEAD
11 - ROCKER ARM AND LIFTER ASSEMBLY
Fig. 19 CYLINDER HEAD TORQUE SEQUENCE
RGENGINE9a-21
CYLINDER HEAD (Continued)
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(5) Slide exhaust manifold and turbocharger on
exhaust manifold studs (Fig. 17).
(6) Install exhaust manifold retaining nuts. Torque
nuts to 32.4N´m.
(7) Install exhaust manifold heat shield (Fig. 17).
Torque bolts to 27.5N´m.
(8) Install turbocharger outlet to charge air cooler
pipe (Fig. 16).
(9) Install thermostat housing to upper radiator
hose pipe (Fig. 16). Install retaining bolt and torque
to 47.1N´m.
(10) Install coolant recovery pressure container
(Refer to 7 - COOLING/ENGINE/COOLANT RECOV-
ERY PRESS CONTAINER - INSTALLATION).
(11) Connect glow plug and coolant temperature
sensor electrical connectors.
(12) Install new cylinder head cover/intake mani-
fold gasket.
(13) Install rocker arm and lifter assemblies.Be
sure to put rocker arm and lifter assemblies in
same location as removed.
(14) Install cylinder head cover/intake manifold
(Fig. 15)(Refer to 9 - ENGINE/CYLINDER HEAD/
CYLINDER HEAD COVER(S) - INSTALLATION).
(15) Install timing belt inner cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(16) Install timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - INSTALLATION) .
(17) Install timing belt outer cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(18)Remove crankshaft and both camshaft
locking pins at this time(Refer to 9 - ENGINE/
VALVE TIMING - STANDARD PROCEDURE).
(19) Install generator (Refer to 8 - ELECTRICAL/
CHARGING/GENERATOR - INSTALLATION).
(20) Install accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(21) Install power steering belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(22) Install right engine mount (Refer to 9 -
ENGINE/ENGINE MOUNTING/RIGHT MOUNT -
INSTALLATION).
(23) Install air cleaner housing assembly.
(24) Refill cooling system (Refer to 7 - COOLING/
ENGINE/COOLANT - STANDARD PROCEDURE).
(25) Install engine cover (Refer to 9 - ENGINE -
INSTALLATION).
(26) Install front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
INSTALLATION).
(27) Connect negative battery cable.CAMSHAFT(S)
DESCRIPTION
The camshafts are made of gray cast iron with
eight machined lobes and four bearing journals (Fig.
20).
OPERATION
When the camshaft rotates the lobes actuate the
hydraulic lifters and rocker arms, forcing downward
on the rocker arms which opens the valves.
REMOVAL
(1) Disconnect negative battery cable.
(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).
(3) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(4) Drain cooling system (Refer to 7 - COOLING/
ENGINE/COOLANT - STANDARD PROCEDURE).
(5) Remove air cleaner housing.
(6) Remove power steering belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(7) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(8) Remove generator (Refer to 8 - ELECTRICAL/
CHARGING/GENERATOR - REMOVAL).
(9) Support engine and remove right engine mount
(Refer to 9 - ENGINE/ENGINE MOUNTING/RIGHT
MOUNT - REMOVAL).
Fig. 20 CAMSHAFTS
1 - INTAKE CAMSHAFT
2 - EXHAUST CAMSHAFT
9a - 22 ENGINERG
CYLINDER HEAD (Continued)
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CYLINDER HEAD COVER(S)
DESCRIPTION
The cylinder head cover is made of cast aluminum
and is also the intake manifold on this engine (Fig.
22).
REMOVAL
CAUTION: Before removing the cylinder head cover/
intake manifold the engine must put at 90É after
TDC. Failure to do so could result in valve and/or
piston damage during reassembly. (Refer to 9 -
ENGINE/VALVE TIMING - STANDARD PROCEDURE)
(1) Disconnect negative battery cable.
(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).
(3) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(4) Drain cooling system (Refer to 7 - COOLING/
ENGINE/COOLANT - STANDARD PROCEDURE).
(5) Rotate engine until 90É after TDC is reached.
Install both camshaft locking pins and the crankshaft
locking pin. (Refer to 9 - ENGINE/VALVE TIMING -
STANDARD PROCEDURE)
(6) Remove air cleaner housing assembly.
(7) Remove power steering belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).(8) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(9) Remove generator (Refer to 8 - ELECTRICAL/
CHARGING/GENERATOR - REMOVAL).
(10) Support engine and remove right engine
mount (Refer to 9 - ENGINE/ENGINE MOUNTING/
RIGHT MOUNT - REMOVAL).
(11) Remove outer timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(12) Remove timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - REMOVAL).
(13) Remove inner timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(14) Disconnect camshaft position sensor, boost
pressure/intake air temperature sensor, EGR sole-
noid, and fuel pressure sensor electrical connectors
(Fig. 23).
Fig. 22 CYLINDER HEAD COVER/INTAKE
MANIFOLD
Fig. 23 ENGINE COMPONENT LOCATIONS
1 - FUEL INJECTOR RETURN LINE
2 - FUEL INJECTOR SUPPLY LINE
3 - OIL SEPARATOR
4 - FUEL INJECTOR
5 - CAMSHAFT POSITION SENSOR
6 - BOOST PRESSURE/INTAKE AIR TEMPERATURE SENSOR
7 - EGR SOLENOID
8 - FUEL PRESSURE SENSOR
9 - CYLINDER HEAD COVER/INTAKE MANIFOL
10 - FUEL RAIL
11 - WIRING HARNESS RETAINING CLIPS
9a - 24 ENGINERG
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(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).
(3) Remove air cleaner housing assembly.
(4) Support engine and remove right engine mount
(Refer to 9 - ENGINE/ENGINE MOUNTING/RIGHT
MOUNT - REMOVAL).
(5) Remove outer timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(6) Remove timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - REMOVAL).
(7) Remove inner timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(8) Remove cylinder head cover/intake manifold
(Refer to 9 - ENGINE/CYLINDER HEAD/CYLIN-
DER HEAD COVER(S) - REMOVAL).(9) Remove rocker arm from lifter (Fig. 30).
INSTALLATION
(1) Clean and inspect gasket sealing surfaces.
(2) Install new gasket on cylinder head.
(3) Lubricate lifter ball end of lifter(s), valve(s),
and rocker arm roller(s) with MopartEngine Oil
Supplement or equivlalent.
(4) Connect rocker arm(s) to lifter and reposition
on valve(s) (Fig. 30).
(5) Install cylinder head cover/intake manifold
(Refer to 9 - ENGINE/CYLINDER HEAD/CYLIN-
DER HEAD COVER(S) - INSTALLATION).
(6) Install inner timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(7) Install timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - INSTALLATION) .
(8) Install outer timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - INSTALLATION).
(9) Install right engine mount (Refer to 9 -
ENGINE/ENGINE MOUNTING/RIGHT MOUNT -
INSTALLATION).
(10) Install air cleaner housing assembly.
Fig. 29 CYLINDER HEAD ASSEMBLY
1 - VALVE SPRING
2 - CYLINDER HEAD BOLT
3 - GLOW PLUG
4 - COOLANT TEMPERATURE SENSOR
5 - CYLINDER HEAD ALIGNMENT DOWEL
6 - CYLINDER BLOCK
7 - CYLINDER LINER
8 - ENGINE BLOCK DECK
9 - CYLINDER HEAD GASKET
10 - CYLINDER HEAD
11 - ROCKER ARM AND LIFTER ASSEMBLY
Fig. 30 ROCKER ARM ASSEMBLY
1 - ROCKER ARM ASSEMBLY
2 - CYLINDER HEAD COVER/INTAKE MANIFOLD
3 - HYDRAULIC LIFTER
4 - CYLINDER HEAD
5 - VALVE
9a - 28 ENGINERG
ROCKER ARMS (Continued)
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(11) Install front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
INSTALLATION).
(12) Connect negative battery cable.
HYDRAULIC LIFTERS
DESCRIPTION
Valve lash is controlled by hydraulic tappets
located inside the cylinder head, in tappet bores
below the camshafts (Fig. 31).
REMOVAL
(1) Disconnect negative battery cable.
(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).(3) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(4) Support engine and remove right engine mount
(Refer to 9 - ENGINE/ENGINE MOUNTING/RIGHT
MOUNT - REMOVAL).
(5) Remove outer timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
CAUTION: Before removing the cylinder head cover/
intake manifold or the timing belt the engine must
put at 90É after TDC. Failure to do so could result in
valve and/or piston damage during reassembly.
(Refer to 9 - ENGINE/VALVE TIMING - STANDARD
PROCEDURE)
(6) Remove timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - REMOVAL).
(7) Remove inner timing belt cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(8) Remove cylinder head cover/intake manifold
(Fig. 32)(Refer to 9 - ENGINE/CYLINDER HEAD/
CYLINDER HEAD COVER(S) - REMOVAL).
Fig. 31 CYLINDER HEAD ASSEMBLY
1 - VALVE SPRING
2 - CYLINDER HEAD BOLT
3 - GLOW PLUG
4 - COOLANT TEMPERATURE SENSOR
5 - CYLINDER HEAD ALIGNMENT DOWEL
6 - CYLINDER BLOCK
7 - CYLINDER LINER
8 - ENGINE BLOCK DECK
9 - CYLINDER HEAD GASKET
10 - CYLINDER HEAD
11 - ROCKER ARM AND LIFTER ASSEMBLY
Fig. 32 CYLINDER HEAD COVER/INTAKE
MANIFOLD
1 - CYLINDER HEAD COVER/INTAKE MANIFOLD BOLTS(LONG)
2 - CYLINDER HEAD COVER/INTAKE MANIFOLD
3 - CYLINDER HEAD
4 - CYLINDER HEAD COVER/INTAKE MANIFOLD GASKET
5 - CYLINDER HEAD COVER/INTAKE MANIFOLD
BOLTS(SHORT)
RGENGINE9a-29
ROCKER ARMS (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
RSFUEL INJECTION14-17
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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. 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 position²Knock sensor
²Throttle position
²A/C switch
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
²A/C control positions
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.
²All monitored components (refer to the Emission
section for On-Board Diagnostics).
14 - 18 FUEL INJECTIONRS
FUEL INJECTION (Continued)
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