gas mileage DODGE TOWN AND COUNTRY 2001 Service Manual

DIAGNOSIS AND TESTING - ENGINE COOLANT
THERMOSTAT
The thermostat is operated by a wax filled cham-
ber (pellet) which is sealed. When heated coolant
reaches a predetermined temperature the wax pellet
expands enough to overcome the closing spring and
water pump pressure, which forces the valve to open.
Coolant leakage into the pellet will cause a thermo-
stat to fail open. Do not attempt to free up a thermo-
stat with a screwdriver.
Thermostat diagnostics is included in powertrain
control module's (PCM) programing for on-board
diagnosis. The malfunction indicator light (MIL) will
illuminate and a diagnostic trouble code (DTC) will
be set when an ªopen too soonº condition occurs. Do
not change a thermostat for lack of heater perfor-
mance or temperature gauge position, unless a DTC
is present. For other probable causes, (Refer to 7 -
COOLING/ENGINE - DIAGNOSIS AND TESTING) .
Thermostat failing shut is the normal long term
mode of failure, and normally, only on high mileage
vehicles. The temperature gauge will indicate this
(Refer to 7 - COOLING/ENGINE - DIAGNOSIS AND
TESTING) .
ENGINE COOLANT
THERMOSTAT - 2.4L
REMOVAL
(1) Drain cooling system below the thermostat
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
(2) Remove radiator upper hose from the coolant
outlet housing (Fig. 7).
(3) Remove coolant outlet housing bolts and hous-
ing (Fig. 8).
(4) Remove thermostat. Discard gasket and clean
both gasket sealing surfaces.
INSTALLATION
(1) Place a new gasket (dipped in clean water) on
the coolant outlet connector surface. Position thermo-
stat with air bleed at the 12 o'clock position in ther-
mostat housing (Fig. 8).
(2) Position the coolant outlet connector and gas-
ket over the thermostat, making sure thermostat is
seated in the thermostat housing.
(3) Position outlet connector to thermostat housing
and install bolts (Fig. 8). Tighten bolts to 28 N´m
(250 in. lbs.).
(4) Install the radiator upper hose to coolant outlet
housing (Fig. 7).
(5) Refill the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
Fig. 7 RADIATOR HOSES TO ENGINE - 2.4L
1 - UPPER HOSE
2 - LOWER HOSE
Fig. 8 Thermostat and Outlet Connector - 2.4L
Engine
1 - THERMOSTAT
2 - GASKET
3 - COOLANT OUTLET CONNECTOR
4 - BOLT
7 - 22 ENGINERS
ENGINE COOLANT THERMOSTAT (Continued)
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CONDITION POSSIBLE CAUSES CORRECTION
6. Freeze point of antifreeze not
correct. Mixture may be too rich.6. Check antifreeze. Adjust
antifreeze-to-water ratio as
required.
7. Coolant not flowing through
system.7. Check for coolant flow in
coolant tank with engine warm
and thermostat open. Coolant
should be observed flowing
through the tank. If flow is not
observed, determine reason for
lack of flow and repair as
necessary.
8. Radiator or A/C condensor fins
are dirty or clogged.8. Clean debris from radiator or
A/C condensor
9. Radiator core is corroded or
plugged.9. Have radiator re-cored or
replaced.
10. Aftermarket A/C installed without
proper A/C condensor.10. Install proper A/C
condensor.
11. Dragging Brakes. 11. Check and correct as
necessary.
12. Non-factory bug screen is being
used reducing airflow.12. Only a factory screen
should be used.
13. Thermostat partially or
completely shut. This is more
prevalent on high mileage vehicles.13. Check thermostat and
replace if necessary.
14. Cylinder head gasket leaking. 14. Check cylinder head gasket
for leaks.
15. Heater core leaking. 15. Check heater cor for leaks.
Repair as necessary.
TEMPERATURE GAUGE
READING IS
INCONSISTENT
(FLUCTUATES, CYCLES
OR IS ERRATIC)1. During cold weather operation,
with the heater blower in the high
position, the gauge reading may
drop slightly. Fluctuation is also
influenced by loads, outside
temperature and extended idle time
with diesel engines.1. A normal condition. No
correction is necessary.
2. Temperature gauge or engine
mounted gauge sensor defective or
shorted. Also, corroded or loose
wiring in this circuit.2. Check operation of gauge
and repair as necessary.
3. Gauge reading rises when vehicle
is brought to a stop after heavy use
(engine still running).3. A normal condition. No
correction needed. Gauge
should return to normal range
after vehicle is driven.
4. Gauge reading high after starting
a warm-iup (hot) engine.4. A normal condition. No
correction needed. Gauge
should return to normal after a
few minutes of engine
operation.
RGCOOLING 2.5L TURBO DIESEL7a-3
COOLING 2.5L TURBO DIESEL (Continued)
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²Throttle Position Sensor
²Torque Management Input (From TCM)
²Transaxle Control Module (TCM)
²Transaxle Gear Engagement (From TCM)
²Vehicle Speed (from transmission control mod-
ule)
NOTE: PCM Outputs:
²Air Conditioning Clutch Relay
²Automatic Shut Down (ASD) and Fuel Pump
Relays
²Data Link Connector (PCI and SCI Transmit)
²Double Start Override
²EGR Solenoid
²Fuel Injectors
²Generator Field
²High Speed Fan Relay
²Idle Air Control Motor
²Ignition Coils
²Leak Detection Pump
²Low Speed Fan Relay
²MTV Actuator
²Proportional Purge Solenoid
²SRV Valve
²Speed Control Relay
²Speed Control Vent Relay
²Speed Control Vacuum Relay
²8 Volt Output
²5 Volt Output
Based on inputs it receives, the powertrain control
module (PCM) adjusts fuel injector pulse width, idle
speed, ignition timing, and canister purge operation.
The PCM regulates the cooling fans, air conditioning
and speed control systems. The PCM changes gener-
ator charge rate by adjusting the generator field.
The PCM adjusts injector pulse width (air-fuel
ratio) based on the following inputs.
²Battery Voltage
²Intake Air Temperature Sensor
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Exhaust Gas Oxygen Content (heated oxygen
sensors)
²Manifold Absolute Pressure
²Throttle Position
The PCM adjusts engine idle speed through the
idle air control motor based on the following inputs.
²Brake Switch
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
²Vehicle Speed (from Transmission Control Mod-
ule)The PCM adjusts ignition timing based on the fol-
lowing inputs.
²Intake Air Temperature
²Engine Coolant Temperature
²Engine Speed (crankshaft position sensor)
²Knock Sensor
²Manifold Absolute Pressure
²Park/Neutral (transmission gear selection)
²Transaxle Gear Engagement
²Throttle Position
The automatic shut down (ASD) and fuel pump
relays are mounted externally, but turned on and off
by the powertrain control module through the same
circuit.
The camshaft and crankshaft signals are sent to
the powertrain control module. If the PCM does not
receive both signals within approximately one second
of engine cranking, it deactivates the ASD and fuel
pump relays. When these relays are deactivated,
power is shut off to the fuel injectors, ignition coils,
fuel pump and the heating element in each oxygen
sensor.
The PCM contains a voltage converter that
changes battery voltage to a regulated 8.0 volts. The
8.0 volts power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5.0 volts supply for the engine
coolant temperature sensor, intake air temperature
sensor, manifold absolute pressure sensor and throt-
tle position sensor.
The PCM engine control strategy prevents reduced
idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage in new PCM. Use
the DRB scan tool to change the mileage in the PCM.
Refer to the appropriate Powertrain Diagnostic Man-
ual and the DRB scan tool.
DIAGNOSTIC TROUBLE CODE
DESCRIPTION
A Diagnostic Trouble Code (DTC) indicates the
PCM has recognized an abnormal condition in the
system.
Remember that DTC's are the results of a sys-
tem or circuit failure, but do not directly iden-
tify the failed component or components.
NOTE: For a list of DTC's, refer to the charts in this
section.
RSELECTRONIC CONTROL MODULES8E-9
POWERTRAIN CONTROL MODULE (Continued)
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²Fuel system monitor
²EGR monitor
²Purge system monitor
²All inputs monitored for proper voltage range.
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.
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
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.
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
²IAC motor 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. 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.
The PCM does not monitor the heated oxygen sen-
sor inputs during wide-open-throttle operation except
for downstream heated oxygen sensor and both
shorted diagnostics. The PCM adjusts injector pulse
width to supply a predetermined amount of addi-
tional fuel.
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.
STANDARD PROCEDURES - OBTAINING
DIAGNOSTIC TROUBLE CODES
BULB CHECK
Each time the ignition key is turned to the ON
position, the malfunction indicator (check engine)
lamp on the instrument panel should illuminate for
approximately 2 seconds then go out. This is done for
a bulb check. When the key is in the power on, but
engine off position, the MIL will remain illuminated
for regulatory purposes.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
ªRead Faultº screen.
(3) Record all the DTC's and ªfreeze frameº infor-
mation shown on the DRB scan tool.
RSELECTRONIC CONTROL MODULES8E-21
POWERTRAIN CONTROL MODULE (Continued)
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(3) Start engine and record oil pressure. Refer to
Specifications for correct oil pressure requirements.
(Refer to 9 - ENGINE - SPECIFICATIONS)
CAUTION: If oil pressure is 0 at idle, do not perform
the 3000 RPM test
(4) If oil pressure is 0 at idle. Shut off engine,
check for pressure relief valve stuck open, a clogged
oil pick-up screen or a damaged oil pick-up tube
O-ring.
(5) After test is complete, remove test gauge and
fitting.
(6) Install oil pressure switch and connector. (Refer
to 9 - ENGINE/LUBRICATION/OIL PRESSURE
SENSOR/SWITCH - INSTALLATION)
OIL
ENGINE OIL LEVEL CHECK
The best time to check engine oil level is after it
has sat overnight, or if the engine has been running,
allow the engine to be shut off for at least 5 minutes
before checking oil level.
Checking the oil while the vehicle is on level
ground will improve the accuracy of the oil level
reading. Remove dipstick and observe oil level. Add
oil only when the level is at or below the ADD mark
(Fig. 88).
STANDARD PROCEDURE - ENGINE OIL AND
FILTER CHANGE
Change engine oil at mileage and time intervals
described in the Maintenance Schedule. (Refer to
LUBRICATION & MAINTENANCE/MAINTE-
NANCE SCHEDULES - DESCRIPTION)
WARNING: NEW OR USED ENGINE OIL CAN BE
IRRITATING TO THE SKIN. AVOID PROLONGED OR
REPEATED SKIN CONTACT WITH ENGINE OIL.
CONTAMINANTS IN USED ENGINE OIL, CAUSED BY
INTERNAL COMBUSTION, CAN BE HAZARDOUS TO
YOUR HEALTH. THOROUGHLY WASH EXPOSED
SKIN WITH SOAP AND WATER. DO NOT WASH
SKIN WITH GASOLINE, DIESEL FUEL, THINNER, OR
SOLVENTS, HEALTH PROBLEMS CAN RESULT. DONOT POLLUTE, DISPOSE OF USED ENGINE OIL
PROPERLY. CONTACT YOUR DEALER OR GOVERN-
MENT AGENCY FOR LOCATION OF COLLECTION
CENTER IN YOUR AREA.
Run engine until achieving normal operating tem-
perature.
(1) Position the vehicle on a level surface and turn
engine off.
(2) Hoist and support vehicle on safety stands.
Refer to Hoisting and Jacking Recommendations.
(Refer to LUBRICATION & MAINTENANCE/HOIST-
ING - STANDARD PROCEDURE)
(3) Remove oil fill cap.
(4) Place a suitable drain pan under crankcase
drain.
(5) Remove drain plug from crankcase and allow
oil to drain into pan. Inspect drain plug threads for
stretching or other damage. Replace drain plug and
gasket if damaged.
(6) Remove oil filter. (Refer to 9 - ENGINE/LUBRI-
CATION/OIL FILTER - REMOVAL)
(7) Install and tighten drain plug in crankcase.
(8) Install new oil filter. (Refer to 9 - ENGINE/LU-
BRICATION/OIL FILTER - INSTALLATION)
(9) Lower vehicle and fill crankcase with specified
type and amount of engine oil. (Refer to LUBRICA-
TION & MAINTENANCE/FLUID TYPES -
DESCRIPTION)
(10) Install oil fill cap.
(11) Start engine and inspect for leaks.
(12) Stop engine and inspect oil level.
NOTE: Care should be exercised when disposing
used engine oil after it has been drained from a
vehicle engine. Refer to the WARNING listed above.
OIL FILTER
DESCRIPTION
The engine oil filter (Fig. 89) is a high quality full-
flow, disposable type. Replace the oil filter with a
Mopartor the equivalent.
REMOVAL
(1) Raise vehicle on hoist.
(2) Position an oil collecting container under oil fil-
ter location.
CAUTION: When servicing the oil filter avoid
deforming the filter can by installing the remove/in-
stall tool band strap against the can to base lock
seam. The lock seam joining the can to the base is
reinforced by the base plate.
Fig. 88 Oil Level
1 - ENGINE OIL LEVEL DIPSTICK
RSENGINE 2.4L9-51
LUBRICATION (Continued)
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OIL
STANDARD PROCEDURE - ENGINE OIL AND
FILTER CHANGE
Change engine oil at mileage and time intervals
described in the Maintenance Schedule. (Refer to
LUBRICATION & MAINTENANCE/MAINTE-
NANCE SCHEDULES - DESCRIPTION)
WARNING: NEW OR USED ENGINE OIL CAN BE
IRRITATING TO THE SKIN. AVOID PROLONGED OR
REPEATED SKIN CONTACT WITH ENGINE OIL.
CONTAMINANTS IN USED ENGINE OIL, CAUSED BY
INTERNAL COMBUSTION, CAN BE HAZARDOUS TO
YOUR HEALTH. THOROUGHLY WASH EXPOSED
SKIN WITH SOAP AND WATER. DO NOT WASH
SKIN WITH GASOLINE, DIESEL FUEL, THINNER, OR
SOLVENTS, HEALTH PROBLEMS CAN RESULT. DO
NOT POLLUTE, DISPOSE OF USED ENGINE OIL
PROPERLY. CONTACT YOUR DEALER OR GOVERN-
MENT AGENCY FOR LOCATION OF COLLECTION
CENTER IN YOUR AREA.
Fig. 98 Engine Oiling System
1 - OIL SUPPLY FOR BALL SOCKET THROUGH PUSH ROD 7 - OUTER ROTOR
2 - OIL SUPPLY PASSAGE FROM SHAFT TO ROCKER ARM 8 - INNER ROTOR
3 - ROCKER SHAFT 9 - RELIEF VALVE
4 - OIL FLOWS TO ONLY ONE PEDASTAL ON EACH HEAD; THIRD
FROM REAR ON RIGHT HEAD, THIRD FROM FRONT ON LEFT
HEAD10 - OIL PAN
5 - ROCKER SHAFT TOWER 11 - OIL SCREEN
6 - CRANKSHAFT 12 - OIL PUMP CASE
Fig. 99 Checking Oil Pressure
1 - OIL FILTER
2 - OIL PRESSURE GAUGE
9 - 132 ENGINE 3.3/3.8LRS
LUBRICATION (Continued)
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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:
²Engine coolant temperature
²Manifold Absolute Pressure (MAP)
²Inlet/Intake air temperature (IAT)
²Crankshaft position (engine speed)
²Camshaft position
²Knock 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:
²Inlet/Intake air temperature
²Engine coolant temperature
²Manifold absolute pressure
²Crankshaft position (engine speed)
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.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
²Purge system monitor
²All inputs monitored for proper voltage range.
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.
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
²Engine coolant temperature
²Engine run time
²Inlet/Intake air temperature
²Vehicle mileageACCELERATION 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.
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
²IAC motor 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. In response, the PCM may
14 - 18 FUEL INJECTIONRS
FUEL INJECTION (Continued)
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The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 19).
OPERATION
Separate controlled ground circuits are run
through the PCM for the upstream O2 sensors.
As vehicles accumulate mileage, the catalytic con-
vertor deteriorates. The deterioration results in a
less efficient catalyst. To monitor catalytic convertor
deterioration, the fuel injection system uses two
heated oxygen sensors. One sensor upstream of the
catalytic convertor, one downstream of the convertor.
The PCM compares the reading from the sensors to
calculate the catalytic convertor oxygen storage
capacity and converter efficiency. Also, the PCM uses
the upstream heated oxygen sensor input when
adjusting injector pulse width.
When the catalytic converter efficiency drops below
emission standards, the PCM stores a diagnostic
trouble code and illuminates the malfunction indica-
tor lamp (MIL).
The O2S produce voltages from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air/fuel mixture), the
sensors produces a low voltage. When there is a
lesser amount present (rich air/fuel mixture) it pro-
duces a higher voltage. By monitoring the oxygen
content and converting it to electrical voltage, the
sensors act as a rich-lean switch.The oxygen sensors are equipped with a heating
element that keeps the sensors at proper operating
temperature during all operating modes. Maintaining
correct sensor temperature at all times allows the
system to enter into closed loop operation sooner.
Also, it allows the system to remain in closed loop
operation during periods of extended idle.
In Closed Loop operation the PCM monitors the
O2S input (along with other inputs) and adjusts the
injector pulse width accordingly. During Open Loop
operation the PCM ignores the O2 sensor input. The
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to both the upstream and downstream
heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating ele-
ments reduce the time required for the sensors to
reach operating temperature.
UPSTREAM OXYGEN SENSOR
The input from the upstream heated oxygen sensor
tells the PCM the oxygen content of the exhaust gas.
Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor input switches from 0 to 1 volt, depend-
ing upon the oxygen content of the exhaust gas in
the exhaust manifold. When a large amount of oxy-
gen is present (caused by a lean air-fuel mixture), the
sensor produces voltage as low as 0.1 volt. When
there is a lesser amount of oxygen present (rich air-
fuel mixture) the sensor produces a voltage as high
as 1.0 volt. By monitoring the oxygen content and
converting it to electrical voltage, the sensor acts as
a rich-lean switch.
The heating element in the sensor provides heat to
the sensor ceramic element. Heating the sensor
allows the system to enter into closed loop operation
sooner. Also, it allows the system to remain in closed
loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse
width based on the upstream heated oxygen sensor
input along with other inputs. In Open Loop, the
PCM adjusts injector pulse width based on prepro-
grammed (fixed) values and inputs from other sen-
sors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor input is
used to detect catalytic convertor deterioration. As
the convertor deteriorates, the input from the down-
stream sensor begins to match the upstream sensor
input except for a slight time delay. By comparing
the downstream heated oxygen sensor input to the
Fig. 19 O2 SENSOR DOWNSTREAM 1/2 - 2.4/3.3/
3.8L
1 - 1/2 02S
2 - 1/1 02S
RSFUEL INJECTION14-31
O2 SENSOR (Continued)
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CLEANING - TIRES
Before delivery of a vehicle, remove the protective
coating on the tires with white sidewalls or raised
white letters. To remove the protective coating, apply
warm water and let it soak for a few minutes. After-
wards, scrub the coating away with a soft bristle
brush. Steam cleaning may also be used to remove
the coating.
CAUTION: DO NOT use gasoline, mineral oil, oil-
based solvent or a wire brush for cleaning.
WHEELS
DESCRIPTION - WHEEL
Original equipment wheels are designed for proper
operation at all loads up to the specified maximum
vehicle capacity.
All models use either steel or aluminum drop-cen-
ter wheels. Every wheel has raised sections between
the rim flanges and rim drop well called safety
humps (Fig. 23). Initial inflation of the tires forces
the bead over these raised sections. In case of air
loss, the safety humps hold the tire in position on the
wheel until the vehicle can be brought to a safe stop.
Cast aluminum wheels require special balance
weights to fit on the flange of the rim (Fig. 24).
When wheel alignment is necessary on a vehicle
with cast aluminum wheels, special wheel clamps are
required to avoid damage to the wheel's finish.The wheel studs and nuts are designed for specific
wheel applications and must be replaced with equiv-
alent parts.
All aluminum wheels have wheel mounting (lug)
nuts with an enlarged nose. This enlarged nose is
necessary to ensure proper retention of the wheels.
DIAGNOSIS AND TESTING - WHEEL
INSPECTION
Inspect wheels for:
²Excessive runout
²Dents, cracks or irregular bends
²Damaged wheel stud (lug) holes
²Air Leaks
NOTE: Do not attempt to repair a wheel by hammer-
ing, heating or welding.
If a wheel is damaged, an original equipment
replacement wheel should be used. When obtaining
replacement wheels, they should be equivalent in
load carrying capacity. The diameter, width, offset,
pilot hole and bolt circle of the wheel should be the
same as the original wheel.
WARNING: FAILURE TO USE EQUIVALENT
REPLACEMENT WHEELS MAY ADVERSELY
AFFECT THE SAFETY AND HANDLING OF THE
VEHICLE.
WARNING: REPLACEMENT WITH USED WHEELS IS
NOT RECOMMENDED. THE SERVICE HISTORY OF
THE WHEEL MAY HAVE INCLUDED SEVERE TREAT-
MENT OR VERY HIGH MILEAGE. THE RIM COULD
FAIL WITHOUT WARNING.
Fig. 23 Safety Rim
1 - TIRE
2 - WELL
3 - SAFETY HUMPS
4 - FLANGE
Fig. 24 Styled Aluminum Wheel Weight
1 - TIRE
2 - WHEEL
3 - STYLED WHEEL WEIGHT
RSTIRES/WHEELS22-13
TIRES (Continued)
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