2002 CHRYSLER CARAVAN air condition

(11) If oil pressure is low and pump is within spec-
ifications, inspect for worn engine bearings or other
reasons for oil pressure loss.
ASSEMBLY
(1) Assemble pump, using new parts as required.
Install the inner rotor with chamfer facing the
cast iron oil pump cover.
(2) Prime oil pump before installation by filling
rotor cavity with engine oil.
(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. 123). The lower intake manifold
is common between the two engines (Fig. 127). It alsoprovides coolant crossover between cylinder heads
and houses the coolant thermostat (Fig. 127).
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)
OPERATION
The intake manifold delivers air to the combustion
chambers. This air allows the fuel delivered by the
fuel injectors to ignite when the spark plugs fire.
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
Fig. 118 Oil Pressure Relief Valve
1 - RELIEF VALVE
2 - SPRING
3 - RETAINER CAP
9 - 146 ENGINE 3.3/3.8LRS
OIL PUMP (Continued)
ProCarManuals.com

INSPECTION
Check manifold for:
²Damage and cracks.
²Mounting surface distortion by using a straight-
edge and thickness gauge.
INSTALLATION - UPPER INTAKE MANIFOLD
(1) If the following components were removed from
manifold, install and tighten to specifications:
CAUTION: The special screws used for the compos-
ite manifold attached components 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 available. For more information and
procedure (Refer to 9 - ENGINE/MANIFOLDS/IN-
TAKE MANIFOLD - STANDARD PROCEDURE - MAN-
IFOLD STRIPPED THREAD REPAIR).²MAP sensor - 1.7 N´m (15 in. lbs.)
²Throttle cable bracket - 5.6 N´m (50 in. lbs.)
(2) Remove covering on lower intake manifold and
clean surfaces.
(3) Inspect manifold gasket condition. Gaskets can
be re-used, if not damaged. To replace, remove gasket
from upper manifold (Fig. 123). Position new gasket
in seal channel and press lightly in-place. Repeat
procedure for each gasket position.
(4) Position upper manifold on lower manifold (Fig.
123). Install and tighten bolts to 12 N´m (105 in. lbs.)
following torque sequence in (Fig. 124).
(5) Connect the MAP sensor electrical connector.
(6) Connect the brake booster and LDP vacuum
hose to intake manifold (Fig. 122).
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. 121).
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.
Fig. 123 INTAKE MANIFOLD - UPPER
1 - BOLT
2 - MAP SENSOR
3 - SCREW
4 - MANIFOLD - UPPER
5 - WIRE HARNESS
6 - GASKET (3 PER CYL. BANK)
Fig. 124 UPPER MANIFOLD TIGHTENING
SEQUENCE
RSENGINE 3.3/3.8L9 - 149
INTAKE MANIFOLD - UPPER (Continued)
ProCarManuals.com

(17) Remove battery shield.
(18) Remove charge air cooler outlet hose.
(19) Remove charge air cooler inlet hose (Fig. 6).
(20) Disconnect upper radiator hose at engine (Fig.
7).
(21) Disconnect lower radiator hose at engine (Fig.
7).
(22) Disconnet brake booster vacuum supply hose.
(23) Disconnect heater core return hose at engine.
(24) Disconnect egr solenoid vacuum line at brake
booster check valve.
(25) Disconnect fuel injector, cam sensor, boost
pressure/intake air temp sensor, fuel rail high pres-
sure, and egr solenoid connectors (Fig. 8).
(26) Disconnect generator electrical connectors.
(27) Disconnect coolant temp sensor and glow plug
electrical connectors.
(28) Disconnect injection pump and A/C compres-
sor electrical connectors.
(29) Disconnect starter electrical connectors.
(30) Disconnect ground wires at engine block.
(31) Raise vehicle on hoist.
(32) Disconnect oil temp sensor, oil pressure sen-
sor, engine speed sensor, and vehicle speed sensor
electrical connector (Fig. 9).(33) Remove front wheels.
(34) Remove the suspension cradle assembly (Refer
to 13 - FRAME & BUMPERS/FRAME/ENGINE
CRADLE CROSSMEMBER - REMOVAL).
(35) Remove both axle shaft assemblies (Refer to 3
- DIFFERENTIAL & DRIVELINE/HALF SHAFT -
REMOVAL).
(36) Disconnect the clutch slave cylinder quick dis-
connect line (RHD only)(Refer to 6 - CLUTCH/SLAVE
CYLINDER - REMOVAL).
(37) Disconnect reverse lamp connector.
(38) Disconnect shifter cables at the tranmission
(Refer to 21 - TRANSMISSION/TRANSAXLE/MAN-
UAL/GEAR SHIFT CABLE - REMOVAL).
(39) Disconnect exhaust pipe from the turbo-
charger downpipe and reposition to right side of vehi-
cle.
(40) Disconnect cabin heater coolant line (Refer to
24 - HEATING & AIR CONDITIONING/CABIN
HEATER/HEATER UNIT - REMOVAL).
(41) Remove front engine mount bracket retaining
bolts from lower radiator support
(42) Lower vehicle. Evacuate the A/C system
(Refer to 24 - HEATING & AIR CONDITIONING/
Fig. 6 CHARGE AIR COOLER HOSES
1 - COOLING MODULE
2 - BYPASS HOSE
3 - UPPER RADIATOR HOSE
4 - CHARGE AIR COOLER OULET HOSE
5 - CHARGE AIR COOLER INLET HOSE
6 - LOWER RADIATOR HOSE
7 - CHARGE AIR COOLER
Fig. 7 UPPER AND LOWER RADIATOR HOSES
1 - COOLANT BYPASS HOSE
2 - RADIATOR ASSEMBLY
3 - UPPER RADIATOR HOSE
4 - COOLING FAN
5 - LOWER RADIATOR HOSE
6 - CHARGE AIR COOLER
7 - RADIATOR BRACKET
RGENGINE9a-5
ENGINE 2.5L TURBO DIESEL (Continued)
ProCarManuals.com

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)
ProCarManuals.com

Catalyst operation is dependent on its ability to
store and release the oxygen needed to complete the
emissions-reducing chemical reactions. As a catalyst
deteriorates, its ability to store oxygen is reduced.
Since the catalyst's ability to store oxygen is some-
what related to proper operation, oxygen storage can
be used as an indicator of catalyst performance.
Refer to the appropriate Diagnostic Information for
diagnosis of a catalyst related Diagnostic Trouble
Code (DTC).
The combustion reaction caused by the catalyst
releases additional heat in the exhaust system, caus-
ing temperature increases in the area of the reactor
under severe operating conditions. Such conditions
can exist when the engine misfires or otherwise does
not operate at peak efficiency.Do notremove spark
plug wires from plugs or by any other means short
out cylinders, if exhaust system is equipped with a
catalytic converter. Failure of the catalytic converter
can occur due to temperature increases caused by
unburned fuel passing through the converter. This
deterioration of the catalyst core can result in exces-
sively high emission levels, noise complaints, and
exhaust restrictions.
Unleaded gasoline must be used to avoid ruining
the catalyst core. Do not allow engine to operate
above 1200 RPM in neutral for extended periods over
5 minutes. This condition may result in excessive
exhaust system/floor pan temperatures because of no
air movement under the vehicle.
The flex joint allows flexing as the engine moves,
preventing breakage that could occur from the back-
and-forth motion of a transverse mounted engine.
CAUTION: Due to exterior physical similarities of
some catalytic converters with pipe assemblies,
extreme care should be taken with replacement
parts. There are internal converter differences
required in some parts of the country (particularly
vehicles built for States with strict emission
requirements) and between model years.
REMOVAL
(1) Loosen clamp and disconnect the muffler/reso-
nator assembly from catalytic converter pipe.
(2) Disconnect downstream oxygen sensor electri-
cal connector (Fig. 4). For removal of downstream
oxygen sensor, (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/O2 SENSOR - REMOVAL).
(3) Remove catalytic converter to exhaust manifold
attaching fasteners (Fig. 5).
(4) Remove catalytic converter and gasket (Fig. 5).
Fig. 4 Downstream Oxygen Sensor
1 - OXYGEN SENSOR CONNECTOR
2 - CATALYTIC CONVERTER
3 - DOWNSTREAM OXYGEN SENSOR
4 - ENGINE HARNESS CONNECTOR
Fig. 5 Catalytic Converter to Exhaust Manifold
1 - FLAG NUT
2 - GASKET
3 - BOLT
4 - CATALYTIC CONVERTER
RSEXHAUST SYSTEM11-5
CATALYTIC CONVERTER (Continued)
ProCarManuals.com

(6) Prior to connecting quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean parts with a lint-free cloth.
Lubricate with clean engine oil.
(7) Insert quick-connect fitting to component being
serviced and into plastic retainer. When a connection
is made, a click will be heard.
(8) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(9) Connect negative cable to battery or auxiliary
jumper terminal.
(10) Use the DRB IIItscan tool ASD Fuel System
Test to pressurize the fuel system. Check for leaks.
PLASTIC RETAINER RING TYPE FITTING
This type of fitting can be identified by the use of a
full-round plastic retainer ring (Fig. 25) usually black
in color.CAUTION: The interior components (O-rings, spac-
ers, retainers) of this type of quick-connect fitting
are not serviced separately. Do not attempt to repair
damaged fittings or fuel lines/tubes. If repair is nec-
essary, replace the complete fuel tube assembly.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING ANY FUEL SYSTEM HOSES,
FITTINGS OR LINES, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED. REFER TO THE FUEL
SYSTEM PRESSURE RELEASE PROCEDURE IN
THIS GROUP.
DISCONNECTION/CONNECTION
(1) Perform fuel pressure release procedure. Refer
to Fuel Pressure Release Procedure in this section.
(2) Disconnect negative battery cable from battery
or auxiliary jumper terminal.
(3) Clean fitting of any foreign material before dis-
assembly.
(4) To release fuel system component from quick-
connect fitting, firmly push fitting towards compo-
nent being serviced while firmly pushing plastic
retainer ring into fitting (Fig. 25). With plastic ring
depressed, pull fitting from component.The plastic
retainer ring must be pressed squarely into fit-
ting body. If this retainer is cocked during
removal, it may be difficult to disconnect fit-
ting. Use an open-end wrench on shoulder of
plastic retainer ring to aid in disconnection.
(5) After disconnection, plastic retainer ring will
remain with quick-connect fitting connector body.
(6) Inspect fitting connector body, plastic retainer
ring and fuel system component for damage. Replace
as necessary.
(7) Prior to connecting quick-connect fitting to
component being serviced, check condition of fitting
and component. Clean parts with a lint-free cloth.
Lubricate with clean engine oil.
(8) Insert quick-connect fitting into component
being serviced until a click is felt.
(9) Verify a locked condition by firmly pulling on
fuel tube and fitting (15-30 lbs.).
(10) Connect negative battery cable to battery or
auxiliary jumper terminal.
(11) Use the DRB IIItscan tool ASD Fuel System
Test to pressurize the fuel system. Check for leaks.
Fig. 25 Plastic Retainer Ring Type Fitting
1 - FUEL TUBE
2 - QUICK CONNECT FITTING
3 - PUSH
4 - PLASTIC RETAINER
5 - PUSH
6 - PUSH
7 - PUSH
8 - PUSH
RSFUEL DELIVERY14-15
QUICK CONNECT FITTING (Continued)
ProCarManuals.com

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
ProCarManuals.com

The PCM compares the upstream and downstream
heated oxygen sensor inputs to measure catalytic con-
vertor efficiency. If the catalyst efficiency drops below
the minimum acceptable percentage, the PCM stores a
diagnostic trouble code in memory, after 2 trips.
During certain idle conditions, the PCM may enter
a variable idle speed strategy. During variable idle
speed strategy the PCM adjusts engine speed based
on the following inputs.
²A/C sense
²Battery voltage
²Battery temperature or Calculated Battery Tem-
perature
²Engine coolant temperature
²Engine run time
²Inlet/Intake air temperature
²Vehicle mileage
ACCELERATION MODE
This is a CLOSED LOOP mode. The PCM recog-
nizes an abrupt increase in Throttle Position sensor
output voltage or MAP sensor output voltage as a
demand for increased engine output and vehicle
acceleration. The PCM increases injector pulse width
in response to increased fuel demand.
²Wide Open Throttle-open loop
DECELERATION MODE
This is a CLOSED LOOP mode. During decelera-
tion the following inputs are received by the PCM:
²A/C sense
²Battery voltage
²Inlet/Intake air temperature
²Engine coolant temperature
²Crankshaft position (engine speed)
²Exhaust gas oxygen content (upstream heated
oxygen sensor)
²Knock sensor
²Manifold absolute pressure
²Throttle position sensor
²IAC motor (solenoid) control changes in response
to MAP sensor feedback
The PCM may receive a closed throttle input from
the Throttle Position Sensor (TPS) when it senses an
abrupt decrease in manifold pressure. This indicates a
hard deceleration (Open Loop). In response, the PCM
may momentarily turn off the injectors. This helps
improve fuel economy, emissions and engine braking.
WIDE-OPEN-THROTTLE MODE
This is an OPEN LOOP mode. During wide-open-
throttle operation, the following inputs are used by
the PCM:
²Inlet/Intake air temperature
²Engine coolant temperature
²Engine speed
²Knock sensor²Manifold absolute pressure
²Throttle position
When the PCM senses a wide-open-throttle condi-
tion through the Throttle Position Sensor (TPS) it de-
energizes the A/C compressor clutch relay. This
disables the air conditioning system and disables
EGR (if equipped).
The PCM adjusts injector pulse width to supply a
predetermined amount of additional fuel, based on
MAP and RPM.
IGNITION SWITCH OFF MODE
When the operator turns the ignition switch to the
OFF position, the following occurs:
²All outputs are turned off, unless 02 Heater
Monitor test is being run. Refer to the Emission sec-
tion for On-Board Diagnostics.
²No inputs are monitored except for the heated
oxygen sensors. The PCM monitors the heating ele-
ments in the oxygen sensors and then shuts down.
FUEL CORRECTION or ADAPTIVE MEMORIES
DESCRIPTION
In Open Loop, the PCM changes pulse width with-
out feedback from the O2 Sensors. Once the engine
warms up to approximately 30 to 35É F, the PCM
goes into closed loopShort Term Correctionand
utilizes feedback from the O2 Sensors. Closed loop
Long Term Adaptive Memoryis maintained above
170É to 190É F unless the PCM senses wide open
throttle. At that time the PCM returns to Open Loop
operation.
OPERATION
Short Term
The first fuel correction program that begins func-
tioning is the short term fuel correction. This system
corrects fuel delivery in direct proportion to the read-
ings from the Upstream O2 Sensor.
The PCM monitors the air/fuel ratio by using the
input voltage from the O2 Sensor. When the voltage
reaches its preset high or low limit, the PCM begins
to add or remove fuel until the sensor reaches its
switch point. The short term corrections then begin.
The PCM makes a series of quick changes in the
injector pulse-width until the O2 Sensor reaches its
opposite preset limit or switch point. The process
then repeats itself in the opposite direction.
Short term fuel correction will keep increasing or
decreasing injector pulse-width based upon the
upstream O2 Sensor input. The maximum range of
authority for short term memory is 25% (+/-) of base
pulse-width. Short term is violated and is lost when
ignition is turned OFF.
RSFUEL INJECTION14-19
FUEL INJECTION (Continued)
ProCarManuals.com