sensor CHRYSLER CARAVAN 2005 Service Manual

(5) Insert a screwdriver between the fuel pump
module and the top of the level sensor housing (Fig.
5). Push level sensor down slightly.
(6) Slide level sensor wires through opening fuel
pump module (Fig. 6).
(7) Slide level sensor out of installation channel in
module.INSTALLATION
(1) Insert level sensor wires into bottom of opening
in module.
(2) Wrap wires into groove in back of level sensor
(Fig. 7).
(3) While feeding wires into guide grooves, slide
level sensor up into channel until it snaps into place
(Fig. 8). Ensure tab at bottom of sensor locks in
place.
Fig. 5 Loosening Level Sensor
1 - LEVEL SENSOR
2 - PRY DOWN ON LEVEL SENSOR
Fig. 6 Level Sensor Removal/Installation
1 - OPENING IN MODULE
2 - FUEL LEVEL SENSOR
Fig. 7 Groove in Back Side of Level Sensor
1 - WRAP WIRES IN GROOVE
2 - REAR VIEW OF LEVEL SENSOR
Fig. 8 Installation Channel
1 - CHANNEL FOR LEVEL SENSOR
2 - PUMP MODULE
14 - 6 FUEL DELIVERYRS
FUEL LEVEL SENDING UNIT / SENSOR (Continued)

(4) Install level sensor wires in connector. Push
the wires up through the connector and then pull
them down until they lock in place. Ensure signal
and ground wires are installed in the correct posi-
tion.
(5) Install locking wedge on connector.
(6) Push connector up into bottom of fuel pump
module electrical connector.
(7) Install fuel pump module. Refer to Fuel Pump
Module in this section.
FUEL LINES
DESCRIPTION - FUEL LINES/HOSES AND
CLAMPS
Also refer to Quick-Connect Fittings.
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. THIS MAY RESULT IN PERSONAL
INJURY OR DEATH.
The lines/tubes/hoses used on fuel injected vehicles
are of a special construction. This is due to the
higher fuel pressures and the possibility of contami-
nated fuel in this system. If it is necessary to replace
these lines/tubes/hoses, use new original equipment
lines/tubes/hoses.
If equipped:The hose clamps used to secure rub-
ber hoses on vehicles are of a special rolled edge con-
struction. This construction is used to prevent the
edge of the clamp from cutting into the hose. Only
these rolled edge type clamps may be used in this
system. All other types of clamps may cut into the
hoses and cause leaks.
Use new original equipment type hose clamps.
STANDARD PROCEDURE - HOSES AND CLAMP
Inspect all hose connections (clamps and quick con-
nect fittings) for completeness and leaks. Replace
cracked, scuffed, or swelled hoses. Replace hoses that
rub against other vehicle components or show sign of
wear.
Fuel injected vehicles use specially constructed
hoses. When replacing hoses, only use hoses marked
EFM/EFI.
When installing hoses, ensure that they are routed
away from contact with other vehicle components
that could rub against them and cause failure. Avoid
contact with clamps or other components that causeabrasions or scuffing. Ensure that rubber hoses are
properly routed and avoid heat sources.
The hose clamps have rolled edges to prevent the
clamp from cutting into the hose. Only use clamps
that are original equipment or equivalent. Other
types of clamps may cut into the hoses and cause
high pressure fuel leaks. Tighten hose clamps to 1
N´m (9 in. lbs.) torque.
Inspect all hose connections such as clamps, cou-
plings and fittings to make sure they are secure and
leaks are not present. The component should be
replaced immediately if there is any evidence of deg-
radation that could result in failure.
Never attempt to repair a plastic fuel line/tube.
Replace as necessary.
Avoid contact of any fuel tubes/hoses with other
vehicle components that could cause abrasions or
scuffing. Be sure that the plastic fuel lines/tubes are
properly routed to prevent pinching and to avoid heat
sources.
FUEL PRESSURE REGULATOR
OPERATION
The fuel system uses a nonadjustable pressure reg-
ulator that maintains fuel system pressure at
approximately 400  34 kPa (58  5 psi). The fuel
pressure regulator contains a diaphragm, calibrated
spring and a fuel return valve. The spring pushes
down on the diaphragm and closes off the fuel return
port. System fuel pressure reflects the amount of fuel
pressure required to open the return port.
The pressure regulator is a mechanical device that
is NOT controlled by the PCM or engine vacuum.
REMOVAL
The fuel pressure regulator is part of the fuel
pump module (Fig. 9). Remove the fuel pump module
from the fuel tank to access the fuel pressure regula-
tor. Refer to the Fuel Pump Module removal in this
section.
(1) Squeeze tangs on pressure regulator retainer
and pull to remove retainer.
(2) Pry fuel pressure regulator out of housing.
(3) Ensure both upper and lower O-rings were
removed with regulator.
INSTALLATION
The fuel pressure regulator is part of the fuel
pump module. Remove the fuel pump module from
the fuel tank to access the fuel pressure regulator.
Refer to the Fuel Pump Module removal in this sec-
tion.
RSFUEL DELIVERY14-7
FUEL LEVEL SENDING UNIT / SENSOR (Continued)

(1) Lightly lubricate the O-rings with clean engine
oil and place them into opening in pump module (Fig.
9).
(2) Push regulator into opening in pump module.
(3) Retaining tabs snap into housing.
FUEL PUMP
DESCRIPTION
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor. The fuel pump module is sus-
pended in fuel in the fuel tank.
OPERATION
The pump draws fuel through a strainer and
pushes it through the motor to the outlet. The pump
contains a check valve. The valve, in the pump out-
let, maintains pump pressure during engine off con-
ditions, for a short while. It is normal for fuel
pressure to drop to zero after cooldown. The fuel
pump relay provides voltage to the fuel pump. The
fuel pump has a maximum deadheaded pressure out-
put of approximately 880 kPa (130 psi). The regula-
tor adjusts fuel system pressure to approximately
400 kpa  34 kpa (58 psi   5 psi).
FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the top of the
fuel tank (Fig. 10), (Fig. 11), and (Fig. 12).The fuel pump module contains the following:
²Electric fuel pump
²Fuel pump reservoir
²Inlet strainer
²Fuel pressure regulator
²Fuel gauge sending unit
Fig. 9 Fuel Pressure Regulator O-rings
1 - UPPER O-RING
2 - LOWER 0-RING
Fig. 10 LEVEL SENSOR - FOLD-IN-FLOOR
2 - FUEL PUMP MODULE
3 - PRESSURE REGULATOR
4 - FUEL LEVEL SENDER
Fig. 11 REGULATOR AND WIRING - FOLD-IN-FLOOR
2 - FUEL RESERVOIR
3 - PRESSURE REGULATOR
6 - GROUND STRAPS
14 - 8 FUEL DELIVERYRS
FUEL PRESSURE REGULATOR (Continued)

²Fuel supply line connection
The inlet strainer, fuel pressure regulator
and fuel level sensor are the only serviceable
items. If the fuel pump or electrical wiring har-
ness requires service, replace the fuel pump
module.
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor.
OPERATION
The pump draws fuel through a strainer and
pushes it through the motor to the outlet. The pump
contains one check valve. The check valve, in the
pump outlet, maintains pump pressure during engine
off conditions. The fuel pump relay provides voltage
to the fuel pump.
The fuel pump has a maximum deadheaded pres-
sure output of approximately 880 kPa (130 psi). The
regulator adjusts fuel system pressure to approxi-
mately 400  34 kPa (58  5 psi).
FUEL PUMP ELECTRICAL CONTROL
Voltage to operate the electric pump is supplied
through the fuel pump relay. For an electrical opera-
tional description of the fuel pump refer to fuel Pump
RelayÐPCM Output.
ELECTRICAL PUMP REPLACEMENT
The electric fuel pump is not serviceable. If the
fuel pump or electrical wiring harness needs replace-
ment, the complete fuel pump module must be
replaced. Perform the Fuel System Pressure Release
procedure before servicing the fuel pump.
REMOVAL
REMOVAL
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.
(1) Remove fuel filler cap and perform Fuel Sys-
tem Pressure Release procedure.
(2) Disconnect negative cable from auxiliary
jumper terminal.
(3) Drain fuel tank, refer to the Fuel Tank proce-
dure in the Fuel Delivery section.
(4) Remove fuel tank, refer to the Fuel Tank
removal section.
(5) Clean top of tank to remove loose dirt and
debris.
(6) Using a brass punch and hammer remove lock-
nut to release pump module (Fig. 13).
Fig. 12 FUEL PUMP MODULE Ð NON FOLD-IN-
FLOOR
1 - INLET STRAINER
2 - FUEL RESERVOIR
3 - FUEL PRESSURE REGULATOR
4 - FUEL LEVEL SENSOR
5 - FILTER
6 - GROUND STRAPS
Fig. 13 FUEL PUMP MODULE LOCKING RING
RSFUEL DELIVERY14-9
FUEL PUMP MODULE (Continued)

FUEL INJECTION
TABLE OF CONTENTS
page page
FUEL INJECTION
OPERATION
OPERATION - INJECTION SYSTEM.......22
OPERATION - MODES OF OPERATION....22
FUEL CORRECTION or ADAPTIVE
MEMORIES..........................24
PROGRAMMABLE COMMUNICATIONS
INTERFACE (PCI) BUS.................25
SYSTEM DIAGNOSIS..................26
SPECIFICATIONS
TORQUE............................26
SPECIAL TOOLS
FUEL...............................27
ACCELERATOR PEDAL
REMOVAL.............................28
INSTALLATION.........................28
CRANKSHAFT POSITION SENSOR
DESCRIPTION.........................29
OPERATION...........................29
REMOVAL.............................30
INSTALLATION - 2.4L....................30
ENGINE SPEED SENSOR
DESCRIPTION.........................30
OPERATION...........................30
FUEL INJECTOR
DESCRIPTION.........................30
OPERATION...........................31
REMOVAL
REMOVAL - 2.4L......................31
REMOVAL - 3.3/3.8L...................31
INSTALLATION
INSTALLATION - 2.4L..................32
INSTALLATION - 3.3/3.8L................32
FUEL PUMP RELAY
DESCRIPTION.........................32
OPERATION...........................32
IDLE AIR CONTROL MOTOR
DESCRIPTION.........................33
OPERATION...........................33REMOVAL.............................33
INSTALLATION.........................33
INLET AIR TEMPERATURE SENSOR
DESCRIPTION.........................34
MAP SENSOR
DESCRIPTION.........................34
OPERATION...........................34
REMOVAL
REMOVAL - 2.4L......................35
REMOVAL - 3.3/3.8L...................35
INSTALLATION
INSTALLATION - 2.4L..................36
INSTALLATION - 3.3/3.8L................36
O2 SENSOR
DESCRIPTION.........................36
OPERATION...........................36
REMOVAL
REMOVAL - UPSTREAM 1/1 - 2.4L........37
REMOVAL - UPSTREAM 1/1 - 3.3/3.8L.....38
REMOVAL - DOWNSTREAM 1/2 - 2.4/3.3/
3.8L................................38
INSTALLATION
INSTALLATION - UPSTREAM 1/1 - 2.4L.....38
INSTALLATION - UPSTREAM 1/1 - 3.3/3.8L . . 39
INSTALLATION DOWNSTREAM 2/1 -
2.4/3.3/3.8L..........................39
THROTTLE BODY
DESCRIPTION.........................39
OPERATION...........................39
REMOVAL.............................40
INSTALLATION.........................40
THROTTLE CONTROL CABLE
REMOVAL.............................40
INSTALLATION.........................40
THROTTLE POSITION SENSOR
DESCRIPTION.........................40
OPERATION...........................41
REMOVAL - 3.3/3.8L.....................41
INSTALLATION - 3.3/3.8L.................41
RSFUEL INJECTION14-21

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

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 INJECTION14-23
FUEL INJECTION (Continued)

²All monitored components (refer to the Emission
section for On-Board Diagnostics).
The PCM compares the upstream and downstream
heated oxygen sensor inputs to measure catalytic
convertor 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 status
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 status
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 sensor
²Manifold 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
14 - 24 FUEL INJECTIONRS
FUEL INJECTION (Continued)

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.
Long Term
The second fuel correction program is the long
term adaptive memory. In order to maintain correct
emission throughout all operating ranges of the
engine, a cell structure based on engine rpm and load
(MAP) is used.
Ther number of cells varies upon the driving con-
ditions. Two cells are used only during idle, based
upon TPS and Park/Neutral switch inputs. There
may be two other cells used for deceleration, based
on TPS, engine rpm, and vehicle speed. The other
twelve cells represent a manifold pressure and an
rpm range. Six of the cells are high rpm and the
other six are low rpm. Each of these cells has a spe-
cific MAP voltage range Typical Adaptive Memory
Fuel Cells.As the engine enters one of these cells the PCM
looks at the amount of short term correction being
used. Because the goal is to keep short term at 0 (O2
Sensor switching at 0.5 volt), long term will update
in the same direction as short term correction was
moving to bring the short term back to 0. Once short
term is back at 0, this long term correction factor is
stored in memory.
The values stored in long term adaptive memory
are used for all operating conditions, including open
loop and cold starting. However, the updating of the
long term memory occurs after the engine has
exceeded approximately 170É-190É F, with fuel control
in closed loop and two minutes of engine run time.
This is done to prevent any transitional temperature
or start-up compensations from corrupting long term
fuel correction.
Long term adaptive memory can change the pulse-
width by as much as 25%, which means it can correct
for all of short term. It is possible to have a problem
that would drive long term to 25% and short term to
another 25% for a total change of 50% away from
base pulse-width calculation.
TYPICAL ADAPTIVE MEMORY FUEL CELLS
Open
ThrottleOpen
ThrottleOpen
ThrottleOpen
ThrottleOpen
ThrottleOpen
Throttle Idle Decel
Vacuum 20 17 13 9 5 0
Above 1,984
rpm1 3 5 7 9 11 13 Drive 15
Below 1,984
rpm02 4 6 8 1012
Neutral14
MAP volt =0 1.4 2.0 2.6 3.3 3.9
Fuel Correction Diagnostics
There are two fuel correction diagnostic routines:
²Fuel System Rich
²Fuel System Lean
A DTC is set and the MIL is illuminated if the
PCM detects either of these conditions. This is deter-
mined based on total fuel correction, short term
times long term.
PROGRAMMABLE COMMUNICATIONS
INTERFACE (PCI) BUS
DESCRIPTION
The Programmable Communication Interface Mul-
tiplex system (PCI Bus) consist of a single wire. The
Body Control Module (BCM) acts as a splice to con-nect each module and the Data Link Connector
(DLC) together. Each module is wired in parallel to
the data bus through its PCI chip set and uses its
ground as the bus reference. The wiring is a mini-
mum 20 gage wire.
OPERATION
Various modules exchange information through a
communications port called the PCI Bus. The Power-
train Control Module (PCM) transmits the Malfunc-
tion Indicator Lamp (Check Engine) On/Off signal
and engine RPM on the PCI Bus. The PCM receives
the Air Conditioning select input, transaxle gear
position inputs over the PCI Bus. The PCM also
receives the air conditioning evaporator temperature
signal from the PCI Bus.
RSFUEL INJECTION14-25
FUEL INJECTION (Continued)

The following components access or send informa-
tion on the PCI Bus.
²Instrument Panel
²Body Control Module
²Air Bag System Diagnostic Module
²Full ATC Display Head (if equipped)
²ABS Module
²Transmission Control Module
²Powertrain Control Module
²Travel Module
²SKIMSYSTEM DIAGNOSIS
OPERATION
The PCM can test many of its own input and out-
put circuits. If the PCM senses a fault in a major
system, the PCM stores a Diagnostic Trouble Code
(DTC) in memory.
For DTC information see On-Board Diagnostics
(Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/POWERTRAIN CONTROL MOD-
ULE - DESCRIPTION) .
SPECIFICATIONS
TORQUE
DESCRIPTION N´m Ft. Lbs. In. Lbs.
MAP SENSOR PLASTIC
MANIFOLD1.7 15
MAP SENSOR
ALUMINUM MANIFOLD3.3 30
POWER STEERING
RESERVOIR PLASTIC
MANIFOLD5.7 50
POWER STEERING
RESERVOIR ALUMINUM
MANIFOLD11.9 105
THROTTLE CABLE
BRACKET PLASTIC
MANIFOLD5.7 50
THROTTLE CABLE
BRACKET ALUMINUM
MANIFOLD11.9 105
EGR TUBE PLASTIC
MANIFOLD5.7 50
EGR TUBE ALUMINUM
MANIFOLD11.9 105
THROTTLE BODY BOLTS
2.4L28 20.65 250  50
THROTTLE BODY BOLTS
3.3/3.8L11.8 8.7 105  20
O2 Sensors 27 20
The composite manifolds uses special Plastic screws. The factory installed Plastic screws can be removed and
installed up to 5 times. Do not exceed the specified torque. These screws must be installed slowly (less than 600
rpms) to avoid melting the parent material. There are service repair screws avialable for repair. They require a
higher torque than the original screws..
14 - 26 FUEL INJECTIONRS
FUEL INJECTION (Continued)