2003 CHRYSLER CARAVAN check engine

FUEL INJECTION
OPERATION
OPERATION - INJECTION SYSTEM
All engines used in this section have a sequential
Multi-Port Electronic Fuel Injection system. The MPI
system is computer regulated and provides precise
air/fuel ratios for all driving conditions. The Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
The PCM can adapt its programming to meet
changing operating conditions.
Fuel is injected into the intake port above the
intake valve in precise metered amounts through
electrically operated injectors. The PCM fires the
injectors in a specific sequence. Under most operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening
and closing the ground path to the injector. Engine
RPM (speed) and manifold absolute pressure (air
density) are theprimaryinputs that determine
injector pulse width.
OPERATION - MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.
There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCM
programming. Inputs from the upstream and down-
stream heated oxygen sensors are not monitored dur-
ing OPEN LOOP modes, except for heated oxygensensor diagnostics (they are checked for shorted con-
ditions at all times).
During CLOSED LOOP modes the PCM monitors
the inputs from the upstream and downstream
heated oxygen sensors. The upstream heated oxygen
sensor input tells the PCM if the calculated injector
pulse width resulted in the ideal air-fuel ratio of 14.7
to one. By monitoring the exhaust oxygen content
through the upstream heated oxygen sensor, the
PCM can fine tune injector pulse width. Fine tuning
injector pulse width allows the PCM to achieve opti-
mum fuel economy combined with low emissions.
For the PCM to enter CLOSED LOOP operation,
the following must occur:
(1) Engine coolant temperature must be over 35ÉF.
²If the coolant is over 35ÉF the PCM will wait 38
seconds.
²If the coolant is over 50ÉF the PCM will wait 15
seconds.
²If the coolant is over 167ÉF the PCM will wait 3
seconds.
(2) For other temperatures the PCM will interpo-
late the correct waiting time.
(3) O2 sensor must read either greater than 0.745
volts or less than 0.29 volt.
(4) The multi-port fuel injection systems has the
following modes of operation:
²Ignition switch ON (Zero RPM)
²Engine start-up
²Engine warm-up
²Cruise
²Idle
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
(5) The engine start-up (crank), engine warm-up,
deceleration with fuel shutoff and wide open throttle
modes are OPEN LOOP modes. Under most operat-
ing conditions, the acceleration, deceleration (with
A/C on), idle and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
²The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input. The
PCM determines basic fuel injector pulse width from
this input.
²The PCM determines atmospheric air pressure
from the MAP sensor input to modify injector pulse
width.
When the key is in the ON position and the engine
is not running (zero rpm), the Auto Shutdown (ASD)
and fuel pump relays de-energize after approximately
14 - 18 FUEL INJECTIONRS
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1 second. Therefore, battery voltage is not supplied to
the fuel pump, ignition coil, fuel injectors and heated
oxygen sensors.
ENGINE START-UP MODE
This is an OPEN LOOP mode. If the vehicle is in
park or neutral (automatic transaxles) or the clutch
pedal is depressed (manual transaxles) the ignition
switch energizes the starter relay when the engine is
not running. The following actions occur when the
starter motor is engaged.
²If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the Auto Shutdown (ASD) relay and fuel pump relay.
If the PCM does not receive both signals within
approximately one second, it will not energize the
ASD relay and fuel pump relay. The ASD and fuel
pump relays supply battery voltage to the fuel pump,
fuel injectors, ignition coil, (EGR solenoid and PCV
heater if equipped) and heated oxygen sensors.
²The PCM energizes the injectors (on the 69É
degree falling edge) for a calculated pulse width until
it determines crankshaft position from the camshaft
position sensor and crankshaft position sensor sig-
nals. The PCM determines crankshaft position within
1 engine revolution.
²After determining crankshaft position, the PCM
begins energizing the injectors in sequence. It adjusts
injector pulse width and controls injector synchroni-
zation by turning the individual ground paths to the
injectors On and Off.
²When the engine idles within  64 RPM of its
target RPM, the PCM compares current MAP sensor
value with the atmospheric pressure value received
during the Ignition Switch On (zero RPM) mode.
Once the ASD and fuel pump relays have been
energized, the PCM determines injector pulse width
based on the following:
²MAP
²Engine RPM
²Battery voltage
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)
²Throttle position
²The number of engine revolutions since cranking
was initiated
During Start-up the PCM maintains ignition tim-
ing at 9É BTDC.
ENGINE WARM-UP MODE
This is an OPEN LOOP mode. The following inputs
are received by the PCM:
²Manifold Absolute Pressure (MAP)
²Crankshaft position (engine speed)
²Engine coolant temperature
²Inlet/Intake air temperature (IAT)²Camshaft position
²Knock sensor
²Throttle position
²A/C switch status
²Battery voltage
²Vehicle speed
²Speed control
²O2 sensors
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts ignition timing and engine idle
speed. Engine idle speed is adjusted through the idle
air control motor.
CRUISE OR IDLE MODE
When the engine is at operating temperature this
is a CLOSED LOOP mode. During cruising or idle
the following inputs are received by the PCM:
²Manifold absolute pressure
²Crankshaft position (engine speed)
²Inlet/Intake air temperature
²Engine coolant temperature
²Camshaft position
²Knock sensor
²Throttle position
²Exhaust gas oxygen content (O2 sensors)
²A/C switch status
²Battery voltage
²Vehicle speed
The PCM adjusts injector pulse width and controls
injector synchronization by turning the individual
ground paths to the injectors On and Off.
The PCM adjusts engine idle speed and ignition
timing. The PCM adjusts the air/fuel ratio according
to the oxygen content in the exhaust gas (measured
by the upstream and downstream heated oxygen sen-
sor).
The PCM monitors for engine misfire. During
active misfire and depending on the severity, the
PCM either continuously illuminates or flashes the
malfunction indicator lamp (Check Engine light on
instrument panel). Also, the PCM stores an engine
misfire DTC in memory, if 2nd trip with fault.
The PCM performs several diagnostic routines.
They include:
²Oxygen sensor monitor
²Downstream heated oxygen sensor diagnostics
during open loop operation (except for shorted)
²Fuel system monitor
²EGR monitor (if equipped)
²Purge system monitor
²Catalyst efficiency monitor
²All inputs monitored for proper voltage range,
rationality.
RSFUEL INJECTION14-19
FUEL INJECTION (Continued)
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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.
The following components access or send informa-
tion on the PCI Bus.
RSFUEL INJECTION14-21
FUEL INJECTION (Continued)
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(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
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. 13).
(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. 14).
(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.
Fig. 12 FUEL RAIL AND INJECTORS 2.4L
1 - Fuel Injectors
2 - Fuel Rail
Fig. 13 FUEL INJECTOR AND RAIL TYPICAL
1 - FUEL RAIL ASSEMBLY
2 - FUEL INJECTOR
3 - FUEL RAIL RECEIVER
Fig. 14 SERVICING FUEL INJECTOR TYPICAL
1 - FUEL INJECTOR
2 - LOCKING SLOT
3 - FUEL RAIL RECEIVER CUP
RSFUEL INJECTION14-27
FUEL INJECTOR (Continued)
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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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(6) Start engine and let idle just long enough to
circulate power steering fluid through the analyzer
and hoses. Shut off engine.
(7) Check power steering fluid level and add fluid
as necessary. Start engine again and let idle until the
air is out of the fluid.
(8) Gauge should read below 300 psi (2068 kPa). If
above, inspect the hoses for restrictions and repair as
necessary. The initial pressure should be in the range
of 100-275 psi (689-1896 kPa) depending on fluid
temperature. The flow meter should read above 1.5
GPM.
CAUTION: The following test procedure involves
testing maximum pump pressure output and flow
control valve operation. Do not leave valve closed
for more than four seconds as the pump could be
damaged.
NOTE:
Power steering pump maximum pressure for
2.4L engines is 1,200 ± 1,350 psi (8,274 ± 9,308 kPa).
Power steering pump maximum pressure for all other
engines is 1,400 ± 1,500 psi (9,653 ± 10,342 kPa).
(9) Close analyzer valve fully three times and
record highest pressure indicated each time. All three
readings must be within specifications. If any of the
three power steering pump pressures are above orbelow specifications, replace pump. (Refer to 19 -
STEERING/PUMP - REMOVAL)
CAUTION: Do not force the steering to operate
against the stops for more than 4 seconds at a time
because pump damage can result.
(10) Once the pump has been verified as working
correctly, completely open the valve on the Power
Steering Analyzer. Turn the steering wheel to the
extreme left until the stop in the steering gear is
met. Hold it there for 2±4 seconds, then release it.
Now turn the steering wheel to the right until the
right stop is met. Hold it there for 2±4 seconds, then
release it. Record the stabilized pressure at each
position. Compare the recorded readings to the spec-
ifications. If the output pressures are not within 100
psi (689 kPa) of one another against either stop or
are below specifications, the steering gear is leaking
internally and must be replaced. (Refer to 19 -
STEERING/GEAR - REMOVAL)
DIAGNOSIS AND TESTING - STEERING
SYSTEM DIAGNOSIS CHARTS
NOTE: There are three diagnosis charts following
that cover POWER STEERING NOISE, STEERING
WHEEL FEEL, and POWER STEERING FLUID.
POWER STEERING NOISE
CONDITION POSSIBLE CAUSES CORRECTION
OBJECTIONABLE HISS
OR WHISTLE*1. Damaged or mispositioned
steering column shaft/coupling dash
panel seal.1. Reposition or replace steering column
shaft/coupling dash panel seal.
2. Noisy valve in power steering
gear.2. Replace power steering gear.
3. Mis-routed power steering hose. 3. Check routing of power steering
hoses. Ensure hoses do not come in
unwanted contact with other components
and objects.
RATTLE OR EXCESSIVE
CLUNK**1. Power steering gear loose on front
suspension crossmember.1. Inspect power steering gear mounting
bolts. Replace as necessary. Tighten to
the specified torque.
2. Front suspension crossmember
mounting fasteners loose at frame.2. Tighten the front suspension
crossmember mounting fasteners to the
specified torque.
3. Loose tie rod (outer or inner). 3. Check tie rod pivot points for wear.
Replace worn/loose parts as required.
4. Loose lower control arm mounting
bolts at front suspension
crossmember.4. Tighten control arm mounting bolts to
the specified torques.
RSSTEERING19-3
STEERING (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
STEERING WHEEL, DASH
OR VEHICLE VIBRATES
DURING LOW SPEED OR
STANDSTILL STEERING
MANEUVERS.1. Air in the fluid of the power
steering system.1. Bleed air from system following the
power steering pump initial operation
service procedure.*
2. Tires not properly inflated. 2. Inflate tires to the specified pressure.
3. Excessive engine vibration. 3. Ensure that the engine is tuned properly.
4. Loose tie rod end jam nut. 4. Tighten the inner to outer tie rod jam nut
to the specified torque.
5.Overcharged air conditioning
system.5.Check air conditioning pump head
pressure and correct as necessary.
6. Grounded engine mount. 6. Repair as necessary.
7. Loose outer tie rod. 7. Replace outer tie rod.
STEERING CATCHES,
SURGES OR STICKS IN
CERTAIN POSITIONS OR
IS DIFFICULT TO TURN.
***1. Low power steering fluid level. 1. Fill power steering fluid reservoir to
specified level and check for leaks.
2. Tires not inflated to specified
pressure.2. Inflate tires to the specified pressure.
3. Lack of lubrication in front lower
control arm ball joints.3. Lubricate ball joints if ball joints are not a
lubricated-for-life type ball joint. If ball joint
is a lubricated-for-life ball joint, replace ball
joint.
4. Worn or binding lower control arm
ball joint.4. Replace lower control arm ball joint.
5. Lack of lubrication in steering gear
outer tie rod ends.5. Lubricate tie rod ends if they are not a
lubricated-for-life type. If tie rod end is a
lubricated-for-life type, replace tie rod end.
6. Loose power steering pump drive
belt.6. Tighten the power steering pump drive
belt to specifications or replace automatic
tensioner where applicable. If drive belt is
worn or glazed, replace belt.
7. Faulty power steering pump
(Perform Power Steering Flow and
Pressure Test).7. Replace power steering pump.
8. Faulty power steering gear
(Perform Power Steering Flow and
Pressure Test).8. Replace power steering gear.
9. Excessive friction in steering
column or intermediate shaft/coupler.9. Isolate and correct condition.
10. Excessive friction in power
steering gear.10. Replace power steering gear.
11. Worn or binding seat and bearing
in front strut assembly.11. Replace seat and bearing in front strut
assembly.
19 - 6 STEERINGRS
STEERING (Continued)
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OPERATION
Turning of the steering wheel is converted into lin-
ear (side-to-side) travel through the meshing of the
helical pinion teeth with the rack teeth in the steer-
ing gear. This travel pushes and pulls the tie rods to
change the direction of the vehicle's front wheels.
Power assist steering provided by the power steer-
ing pump is controlled by an open center, rotary type
control valve which directs oil from the pump to
either side of the integral rack piston upon demand.
Road feel is controlled by the diameter of a torsion
bar which initially steers the vehicle. As required
steering effort increases, as in a turn, the torsion bar
twists, causing relative rotary motion between the
rotary valve body and the valve spool. This move-
ment directs oil behind the integral rack piston
which, in turn, builds hydraulic pressure and assists
in the turning effort.
Manual steering control of the vehicle can be main-
tained if power steering assist is lost. However,
under this condition, steering effort is significantly
increased.
WARNING
WARNINGS AND CAUTIONS
WARNING: POWER STEERING FLUID, ENGINE
PARTS AND EXHAUST SYSTEM MAY BE
EXTREMELY HOT IF ENGINE HAS BEEN RUNNING.
DO NOT START ENGINE WITH ANY LOOSE OR DIS-
CONNECTED HOSES. DO NOT ALLOW HOSES TO
TOUCH HOT EXHAUST MANIFOLD OR CATALYST.
WARNING: FLUID LEVEL SHOULD BE CHECKED
WITH THE ENGINE OFF TO PREVENT PERSONAL
INJURY FROM MOVING PARTS.
CAUTION: When the system is open, cap all open
ends of the hoses, power steering pump fittings or
power steering gear ports to prevent entry of for-
eign material into the components.
REMOVAL
REMOVAL - LHD GEAR
(1) Remove cap from power steering fluid reser-
voir.
(2) Using a siphon pump, remove as much fluid as
possible from the power steering fluid reservoir.Use
care not to damage the filter mesh below the
fluid surface.
CAUTION: Locking the steering column in the
straight-ahead position will prevent the clockspring
from being accidentally over-extended when the
steering column is disconnected from the interme-
diate steering coupler.
(3) Position the steering wheel in the STRAIGHT-
AHEAD position. Lock the steering wheel in place
using a steering wheel holding tool.
(4) With the vehicle on the ground, disconnect the
steering column shaft coupler from the steering gear
intermediate coupler (Fig. 2).
Fig. 2 Steering Column Shaft To Intermediate Shaft
Attachment
1 - STEERING COLUMN SHAFT COUPLER
2 - NUT
3 - SAFETY PIN
4 - INTERMEDIATE SHAFT
5 - PINCH BOLT
RSGEAR19-27
GEAR (Continued)
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