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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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 is a specific
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 updatein 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.
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
²SKIM
14 - 20 FUEL INJECTIONRS
FUEL INJECTION (Continued)
ProCarManuals.com
OPERATION
The Transmission Control Module (TCM) supplies
the road speed and distance traveled inputs to the
PCM. From these inputs and the throttle position
sensor input, the PCM determines when a decelera-
tion condition occurs.
FUEL INJECTOR
DESCRIPTION
The injectors are positioned in the intake manifold
or cylinder head with the nozzle ends directly above
the intake valve port (Fig. 9).
OPERATION
The fuel injectors are 12 volt electrical solenoids
(Fig. 10). The injector contains a pintle that closes off
an orifice at the nozzle end. When electric current is
supplied to the injector, the armature and needle
move a short distance against a spring, allowing fuel
to flow out the orifice. Because the fuel is under high
pressure, a fine spray is developed in the shape of a
hollow cone or two streams. The spraying action
atomizes the fuel, adding it to the air entering the
combustion chamber. Fuel injectors are not inter-
changeable between engines.
The PCM provides battery voltage to each injector
through the ASD relay. Injector operation is con-
trolled by a ground path provided for each injector by
the PCM. Injector on-time (pulse-width) is variable,
and is determined by the PCM processing all the
data previously discussed to obtain the optimum
injector pulse width for each operating condition. Thepulse width is controlled by the duration of the
ground path provided.
REMOVAL
REMOVAL - 2.4L
The fuel rail must be removed first (Fig. 11). Refer
to Fuel Rail Removal in this section.
(1) Disconnect injector wiring connector from injec-
tor.
(2) Position fuel rail assembly so that the fuel
injectors are easily accessible (Fig. 12).
(3) Rotate injector and pull injector out of fuel rail.
The clip will stay on the injector.
(4) Check injector O-ring for damage. If O-ring is
damaged, it must be replaced. If injector is reused, a
protective cap must be installed on the injector tip to
Fig. 9 Fuel Injector Location - Typical
1 - FUEL RAIL
2 - INTAKE MANIFOLD
3 - FUEL INJECTORS
Fig. 10 FUEL INJECTOR - TYPICAL
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
Fig. 11 FUEL RAIL AND INJECTORS 2.4L
1 - Fuel Injectors
2 - Fuel Rail
RSFUEL INJECTION14-25
ENGINE SPEED SENSOR (Continued)
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prevent damage. Replace the injector clip if it is dam-
aged.
(5) Repeat for remaining injectors.
REMOVAL - 3.3/3.8L
(1) Disconnect the negative battery cable.
(2) Remove the Intake Manifold, (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL)
(3) Disconnect injector wiring connector from injec-
tor.
(4) Position fuel rail assembly so that the fuel
injectors are easily accessible (Fig. 12).
(5) Rotate injector and pull injector out of fuel rail.
The clip will stay on the injector.
(6) Check injector O-ring for damage. If O-ring is
damaged, it must be replaced. If injector is reused, a
protective cap must be installed on the injector tip to
prevent damage. Replace the injector clip if it is dam-
aged.
(7) Repeat for remaining injectors.
INSTALLATION
INSTALLATION - 2.4L
The fuel rail must be removed first. Refer to Fuel
Injector Rail Removal in this section.(1) Before installing an injector the rubber O-ring
must be lubricated with a drop of clean engine oil to
aid in installation.
(2) Install injector clip by sliding open end into the
top slot of the injector. The edge of the receiver cup
will slide into the side slots of clip.
(3) Install injector top end into fuel rail receiver
cap. Be careful not to damage O-ring during installa-
tion (Fig. 13).
(4) Repeat steps for remaining injectors.
(5) Connect fuel injector wiring.
INSTALLATION - 3.3/3.8L
(1) Before installing an injector the rubber O-ring
must be lubricated with a drop of clean engine oil to
aid in installation.
(2) Install injector clip by sliding open end into the
top slot of the injector. The edge of the receiver cup
will slide into the side slots of clip (Fig. 12).
(3) Install injector top end into fuel rail receiver
cap. Be careful not to damage O-ring during installa-
tion (Fig. 12).
(4) Repeat steps for remaining injectors.
(5) Install fuel rail, refer to Fuel Rail in the Fuel
Delivery section.
(6) Connect fuel injector wiring.
(7) Install the Intake Manifold, (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION)
(8) Connect the negative battery cable.
Fig. 12 FUEL INJECTOR AND RAIL TYPICAL
1 - FUEL RAIL ASSEMBLY
2 - FUEL INJECTOR
3 - FUEL RAIL RECEIVER
Fig. 13 SERVICING FUEL INJECTOR TYPICAL
1 - FUEL INJECTOR
2 - LOCKING SLOT
3 - FUEL RAIL RECEIVER CUP
14 - 26 FUEL INJECTIONRS
FUEL INJECTOR (Continued)
ProCarManuals.com
INSTALLATION - FUEL RAIL
(1) Install fuel rail to intake manifold/cylinder
head cover (Fig. 2). Torque retaining bolts to
27.5N´m.
(2) Install engine electrical harness retainers from
the fuel rail retaining bolts/studs. (Fig. 2)
(3) Connect fuel rail high pressure sensor electri-
cal connector. (Fig. 2)
(4) Connect fuel rail return line. (Fig. 2)
(5) Connect fuel rail supply line. (Fig. 2)
(6) Connect fuel injector high pressure lines. (Fig.
2)
(7) Install engine cover (Refer to 9 - ENGINE -
INSTALLATION).
(8) Connect negative battery cable.
FUEL FILTER / WATER
SEPARATOR
DESCRIPTION
The fuel filter/water separator assembly is located
under the vehicle in front of the rear axle assembly
(Fig. 3). The assembly also includes the fuel heater
and Water-In-Fuel (WIF) sensor.
OPERATION
The fuel filter/water separator protects the fuel
injection pump by removing water and contaminants
from the fuel. The construction of the filter/separator
allows fuel to pass through it, but helps prevent
moisture (water) from doing so. Moisture collects at
the bottom of the canister.
Fig. 2 FUEL RAIL COMPONENTS
1 - FUEL INJECTOR RETURN LINE
2 - FUEL INJECTOR HIGH PRESSURE 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 MANIFOLD
10 - FUEL RAIL
Fig. 3 FUEL FILTER/WATER SEPARATOR
1 - LIFT PUMP RETAINING BOLTS
2 - LIFT PUMP
3 - FUEL FILTER/WATER SEPARATOR HOUSING
4 - FUEL HEATER
5 - CHECK BALL
6 - O-RING
7 - FLOW DIVERTER
8 - FUEL FILTER
9 - O-RING
10 - FUEL FILTER BOWL ASSEMBLY
RGFUEL DELIVERY14a-5
FUEL RAIL (Continued)
ProCarManuals.com
Refer to the maintenance schedules for the recom-
mended fuel filter replacement intervals.
For draining of water from canister, refer to Fuel
Filter/Water Separator Removal/Installation section.
A Water-In-Fuel (WIF) sensor is part of the fuel fil-
ter cap. Refer to Water-In-Fuel Sensor Description/
Operation.
The fuel heater is installed into the filter/separator
housing above the fuel filter. Refer to Fuel Heater
Description/Operation.
FUEL LINES
DESCRIPTION
DESCRIPTION
All fuel lines up to the fuel injection pump are con-
sidered low-pressure. This includes the fuel lines
from: the fuel tank to the fuel transfer pump, and
the fuel transfer pump to the fuel injection pump.
The fuel return lines and the fuel drain lines are also
considered low-pressure lines. High-pressure lines
are used between the fuel injection pump and the
fuel injectors. Also refer to High-Pressure Fuel Lines
Description/Operation.
DESCRIPTION - HIGH PRESSURE FUEL LINES
The high-pressure fuel lines are the 4 lines located
between the fuel injection pump and the fuel injec-
torsctor tubes. All other fuel lines are considered low-
pressure lines.
OPERATION - HIGH PRESSURE FUEL LINES
CAUTION: The high-pressure fuel lines cannot con-
tact each other or other components. Do not
attempt to weld high-pressure fuel lines or to repair
lines that are damaged. If lines are ever kinked or
bent, they must be replaced. Use only the recom-
mended lines when replacement of high-pressure
fuel line is necessary.
High-pressure fuel lines deliver fuel under
extremely high pressure from the injection pump to
the fuel injectors. The lines expand and contract from
the high-pressure fuel pulses generated during the
injection process. All high-pressure fuel lines are of
the same length and inside diameter. Correct high-
pressure fuel line usage and installation is critical to
smooth engine operation.
WARNING: USE EXTREME CAUTION WHEN
INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH
A SHEET OF CARDBOARD. HIGH FUEL INJECTIONPRESSURE CAN CAUSE PERSONAL INJURY IF
CONTACT IS MADE WITH THE SKIN.
DIAGNOSIS AND TESTING - HIGH PRESSURE
FUEL LINES
High-pressure fuel line leaks can cause starting
problems and poor engine performance.
WARNING: DUE TO EXTREME FUEL PRESSURES,
USE EXTREME CAUTION WHEN INSPECTING FOR
HIGH-PRESSURE FUEL LEAKS. DO NOT GET YOUR
HAND NEAR A SUSPECTED LEAK. INSPECT FOR
HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF
CARDBOARD. HIGH FUEL INJECTION PRESSURE
CAN CAUSE PERSONAL INJURY IF CONTACT IS
MADE WITH THE SKIN.
Start the engine. Move the cardboard over the
high-pressure fuel lines and check for fuel spray onto
the cardboard (Fig. 4). If a high-pressure line connec-
tion is leaking, bleed the system and tighten the con-
nection. Refer to the Air Bleed Procedure in this
group for procedures. Replace damaged, restricted or
leaking high-pressure fuel lines with the correct
replacement line.
Fig. 4 Typical Test for Leaks with Cardboard
1 - HIGH-PRESSURE LINE
2 - CARDBOARD
3 - FITTING
14a - 6 FUEL DELIVERYRG
FUEL FILTER / WATER SEPARATOR (Continued)
ProCarManuals.com
CAUTION: The high-pressure fuel lines cannot con-
tact each other or other components. Do not
attempt to weld high-pressure fuel lines or to repair
lines that are damaged. Only use the recommended
lines when replacement of high-pressure fuel line is
necessary.
FUEL TRANSFER PUMP
DESCRIPTION
The fuel transfer pump (fuel lift pump) is located
under the vehicle in front of the rear axle assembly
(Fig. 5). The 12±volt electric vane-type pump is oper-
ated and controlled by the Engine Control Module
(ECM).
OPERATION
The purpose of the fuel transfer pump is to supply
(transfer) a low-pressure fuel source:fromthe fuel
tank,throughthe fuel filter/water separator andto
the fuel injection pump. Here, the low-pressure is
raised to a high-pressure by the fuel injection pump
for operation of the high-pressure fuel injectors.
The fuel transfer pump is controlled by the Engine
Control Module(ECM). The ECM turns the fuel
transfer pump on for 30 seconds when the ignition
ket is turned ªONº.
With the ignition ªONº and fuel tranfer pump run-
ning, the low-pressure fuel pressure should be 13-17
psi.
FUEL INJECTION PUMP
DESCRIPTION
A radial-piston pump is used as the high pressure
pump for fuel pressure generation (Fig. 6).
REMOVAL
(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL)
(3) Remove air cleaner housing assembly.
(4) Remove power steering belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(5) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
Fig. 5 FUEL TRANSFER(LIFT) PUMP LOCATION
1 - LIFT PUMP RETAINING BOLTS
2 - LIFT PUMP
3 - FUEL FILTER/WATER SEPARATOR HOUSING
4 - FUEL HEATER
5 - CHECK BALL
6 - O-RING
7 - FLOW DIVERTER
8 - FUEL FILTER
9 - O-RING
10 - FUEL FILTER BOWL ASSEMBLY
Fig. 6 FUEL INJECTION PUMP
1 - FUEL INJECTION PUMP
2 - INJECTION PUMP PRESSURE SOLENOID
RGFUEL DELIVERY14a-7
FUEL LINES (Continued)
ProCarManuals.com
Assemble hoses on Power Steering Analyzer, Spe-
cial Tool 6815, as shown. Install Pressure Hose, Spe-
cial Tool 6905 (in 6893 kit), in the inlet fitting on
Power Steering Analyzer. Install Pressure Hose, Spe-
cial Tool 6713 (in 6815 kit) on Pressure Hose, Special
Tool 6905. Install Pressure Hose, Special Tool 6959,
in the outlet fitting on Power Steering Analyzer.
Install the following adapters from Adapter Set,
Special Tool 6893 (Fig. 2), on the analyzer hose ends:
Install Adapter Fitting, Special Tool 6844, on Pres-
sure Hose, Special Tool 6713. Install Adapter Fitting,
Special Tool 6826, on Pressure Hose, Special Tool
6959.
CAUTION: To prevent personal injury, safety gog-
gles should be worn at all times when performing
any test procedures on the power steering pump or
power steering gear.
The following procedure is to be used to test the
operation of the power steering system on the vehi-
cle.
(1) Check belt tension and adjust as necessary.
(2) Disconnect the power steering fluid pressure
hose from the power steering pump (Fig. 3) (Fig. 4).
(3) Connect Adapter Fitting, Special Tool 6844,
attached to pressure hose from inlet (gauge end) of
Power Steering Analyzer to the pressure fitting on
the power steering pump.
(4) Connect vehicle power steering fluid pressure
hose to Adapter Fitting, Special Tool 6826, which
should be already installed in the outlet hose (valve
end) of Power Steering Analyzer.NOTE: During the next few steps, do not steer vehi-
cle as air will be forced into the steering gear.
(5) Completely open valve on Power Steering Ana-
lyzer.
Fig. 2 Power Steering Analyzer Adapters 6893
Fig. 3 Pressure Hose Connection To Power Steering
Pump - 2.4L Engine
1 - POWER STEERING FLUID RETURN HOSE
2 - POWER STEERING PUMP
3 - POWER STEERING FLUID PRESSURE HOSE
Fig. 4 Supply & Pressure Hoses At Pump - 3.3L/3.8L
Engine
1 - PRESSURE HOSE AND FITTING
2 - SUPPLY HOSE AND CLAMP
3 - POWER STEERING PUMP
19 - 2 STEERINGRS
STEERING (Continued)
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