THROTTLE POSITION SENSOR (TPS)
The TPS mounts to the side of the throttle body
(Fig. 13).
The TPS connects to the throttle blade shaft. The
TPS is a variable resistor that provides the Power-
train Control Module (PCM) with an input signal
(voltage). The signal represents throttle blade posi-
tion. As the position of the throttle blade changes,
the resistance of the TPS changes.
The PCM supplies approximately 5 volts to the
TPS. The TPS output voltage (input signal to the
powertrain control module) represents throttle blade
position. The TPS output voltage to the PCM varies
from approximately 0.40 volt at minimum throttle
opening (idle) to a maximum of 3.80 volts at wide
open throttle.
Along with inputs from other sensors, the PCM
uses the TPS input to determine current engine oper-
ating conditions. The PCM also adjusts fuel injector
pulse width and ignition timing based on these
inputs.
LOCK KEY CYLINDER
The lock cylinder is inserted in the end of the
housing opposite the ignition switch. The ignition key
rotates the cylinder to 5 different detents (Fig. 14):
²Accessory
²Off (lock)
²Unlock
²On/Run
²Start
KNOCK SENSOR
The knock sensor threads into the side of the cyl-
inder block in front of the starter motor. When the
knock sensor detects a knock in one of the cylinders,
it sends an input signal to the PCM. In response, the
PCM retards ignition timing for all cylinders by a
scheduled amount.
Knock sensors contain a piezoelectric material
which constantly vibrates and sends an input voltage
(signal) to the PCM while the engine operates. As the
intensity of the crystal's vibration increase, the knock
sensor output voltage also increases.
Fig. 12 Engine Coolant Temperature SensorÐ3.3/
3.8LFig. 13 Throttle Position Sensor and Idle Air Control
Motor
Fig. 14 Ignition Lock Cylinder Detents
NSIGNITION SYSTEM 8D - 7
GENERAL INFORMATION (Continued)
either the crankshaft position sensor/camshaft posi-
tion sensor 8 volt supply circuit, or the camshaft
position sensor output or ground circuits. Use the
DRB scan tool to test the camshaft position sensor
and the sensor circuits. Refer to the appropriate Pow-
ertrain Diagnostics Procedure Manual. Refer to the
wiring diagrams section for circuit information.
IGNITION TIMING PROCEDURE
The engines for this vehicle, use a fixed ignition
system. The PCM regulates ignition timing. Basic
ignition timing is not adjustable.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST
Refer to Group 14, Fuel System for Diagnosis and
Testing.
CAMSHAFT POSITION SENSOR AND CRANKSHAFT
POSITION SENSOR
The output voltage of a properly operating cam-
shaft position sensor or crankshaft position sensor
switches from high (5.0 volts) to low (0.3 volts). By
connecting an Moper Diagonostic System (MDS) and
engine analyzer to the vehicle, technicians can view
the square wave pattern.
ENGINE COOLANT TEMPERATURE SENSOR
Refer to Group 14, Fuel System for Diagnosis and
Testing.
INTAKE AIR TEMPERATURE SENSOR
Refer to Group 14, Fuel System, for Diagnosis and
Testing.
SPARK PLUG CONDITION
NORMAL OPERATING CONDITIONS
The few deposits present will be probably light tan
or slightly gray in color with most grades of commer-
cial gasoline (Fig. 23). There will not be evidence of
electrode burning. Gap growth will not average more
than approximately 0.025 mm (.001 in) per 1600 km
(1000 miles) of operation for non platinum spark
plugs. Non-platnium spark plugs that have normal
wear can usually be cleaned, have the electrodes filed
and regapped, and then reinstalled.
CAUTION: Never attempt to file the electrodes or
use a wire brush for cleaning platinum spark plugs.
This would damage the platinum pads which would
shorten spark plug life.
Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with MMT
may coat the entire tip of the spark plug with a rustcolored deposit. The rust color deposits can be misdi-
agnosed as being caused by coolant in the combustion
chamber. Spark plug performance is not affected by
MMT deposits.
COLD FOULING (CARBON FOULING)
Cold fouling is sometimes referred to as carbon
fouling because the deposits that cause cold fouling
are basically carbon (Fig. 23). A dry, black deposit on
one or two plugs in a set may be caused by sticking
valves or misfire conditions. Cold (carbon) fouling of
the entire set may be caused by a clogged air cleaner.
Cold fouling is normal after short operating peri-
ods. The spark plugs do not reach a high enough
operating temperature during short operating peri-
ods.Replace carbon fouled plugs with new
spark plugs.
FUEL FOULING
A spark plug that is coated with excessive wet fuel
is called fuel fouled. This condition is normally
observed during hard start periods.Clean fuel
fouled spark plugs with compressed air and
reinstall them in the engine.
OIL FOULING
A spark plug that is coated with excessive wet oil
is oil fouled. In older engines, wet fouling can be
caused by worn rings or excessive cylinder wear.
Break-in fouling of new engines may occur before
normal oil control is achieved.Replace oil fouled
spark plugs with new ones.
OIL OR ASH ENCRUSTED
If one or more plugs are oil or ash encrusted, eval-
uate the engine for the cause of oil entering the com-
bustion chambers (Fig. 24). Sometimes fuel additives
can cause ash encrustation on an entire set of spark
Fig. 23 Normal Operation and Cold (Carbon) Fouling
NSIGNITION SYSTEM 8D - 11
DIAGNOSIS AND TESTING (Continued)
2.4L ENGINE
INDEX
page page
DESCRIPTION AND OPERATION
CAMSHAFT POSITION SENSOR............ 17
CRANKSHAFT POSITION SENSOR.......... 16
FIRING ORDERÐ2.4L.................... 16
INTAKE AIR TEMPERATURE SENSORÐ2.4L . . . 17
REMOVAL AND INSTALLATION
CAMSHAFT POSITION SENSOR............ 19
CRANKSHAFT POSITION SENSOR.......... 19
ENGINE COOLANT TEMPERATURE SENSORÐ
2.4L................................. 20
IGNITION COILÐ2.4L..................... 18
INTAKE AIR TEMPERATURE SENSORÐ2.4L . . . 21KNOCK SENSORÐ2.4L................... 21
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ2.4/3.3/3.8L.................. 20
SPARK PLUG CABLE SERVICEÐ2.4L........ 18
SPARK PLUG SERVICE................... 18
THROTTLE POSITION SENSOR............ 20
SPECIFICATIONS
IGNITION COIL......................... 22
SPARK PLUG CABLE RESISTANCEÐ2.4L..... 22
SPARK PLUG........................... 22
TORQUE.............................. 22
DESCRIPTION AND OPERATION
FIRING ORDERÐ2.4L
CRANKSHAFT POSITION SENSOR
The PCM determines what cylinder to fire from the
crankshaft position sensor input and the camshaft
position sensor input. The second crankshaft counter-
weight has machined into it two sets of four timing
reference notches and a 60 degree signature notch
(Fig. 1). From the crankshaft position sensor input
the PCM determines engine speed and crankshaft
angle (position).The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltage
goes low (less than 0.3 volts). When a notch aligns
with the sensor, voltage switches high (5.0 volts). As
a group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.
If available, an oscilloscope can display the square
wave patterns of each voltage pulse. From the width
of the output voltage pulses, the PCM calculates
engine speed. The width of the pulses represent the
amount of time the output voltage stays high before
switching back to low. The period of time the sensor
output voltage stays high before switching back to
low is referred to as pulse width. The faster the
FIRING ORDERÐ2.4L
Fig. 1 Timing Reference Notches
8D - 16 IGNITION SYSTEMNS
(1) Install target magnet in end of camshaft.
Tighten mounting screw to 5.65 N´m (50 in. lbs.)
torque.
(2) Install a new O-ring on sensor.
(3) Install camshaft position sensor. Tighten sensor
mounting screws to 9.6 N´m (85 in. lbs.) torque.
(4) Attach engine harness connector to camshaft
position sensor.
(5) Install air cleaner inlet tube and filtered air
tube.
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ2.4/3.3/3.8L
REMOVAL
(1) Disconnect electrical connector from MAP sen-
sor (Fig. 12).
(2) Remove two screws holding sensor to the
intake manifold.
INSTALLATION
(1) Reverse the above procedure for installation.
THROTTLE POSITION SENSOR
Refer to Group 14, Fuel Injection Section, for
Removal/Installation.
ENGINE COOLANT TEMPERATURE SENSORÐ2.4L
The coolant sensor threads into the top of the ther-
mostat housing (Fig. 13). New sensors have sealant
applied to the threads.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7- COOLING.
Fig. 10 Target Magnet
Fig. 11 Target Magnet Installation
Fig. 12 Map Absolute Pressure Sensor
Fig. 13 Engine Coolant Temperature SensorÐ2.4L
8D - 20 IGNITION SYSTEMNS
REMOVAL AND INSTALLATION (Continued)
REMOVAL
(1) With the engine cold, drain coolant until level
drops below cylinder head. Refer to Group 7, Cooling
System.
(2) Disconnect coolant sensor electrical connector.
(3) Remove coolant sensor.
INSTALLATION
(1) Install coolant sensor. Tighten sensor to 7 N´m
(60 in. lbs.) torque.
(2) Attach electrical connector to sensor.
(3) Fill cooling system. Refer to Group 7, Cooling
System.
KNOCK SENSORÐ2.4L
The knock sensor threads into the side of the cyl-
inder block in front of the starter (Fig. 14).
REMOVAL
(1) Disconnect electrical connector from knock sen-
sor.
(2) Use a crow foot socket to remove the knock
sensors.
INSTALLATION
(1) Install knock sensor. Tighten knock sensor to
10 N´m (7 ft. lbs.) torque.Over or under tighten-
ing effects knock sensor performance, possibly
causing improper spark control.
(2) Attach electrical connector to knock sensor.
INTAKE AIR TEMPERATURE SENSORÐ2.4L
The intake air temperature sensor threads into the
intake manifold plenum (Fig. 15).
REMOVAL
(1) Remove electrical connector from sensor.
(2) Remove sensor.
INSTALLATION
(1) Install sensor. Tighten sensor to 28 N´m (20 ft.
lbs.) torque.
(2) Attach electrical connector to sensor.
Fig. 14 Knock Sensor
Fig. 15 Intake Air Temperature Sensor
NSIGNITION SYSTEM 8D - 21
REMOVAL AND INSTALLATION (Continued)
3.0L ENGINE
INDEX
page page
DESCRIPTION AND OPERATION
CAMSHAFT POSITION SENSOR............ 23
FIRING ORDERÐ3.0L.................... 23
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR............................. 23
REMOVAL AND INSTALLATION
CRANKSHAFT POSITION SENSOR.......... 25
ENGINE COOLANT TEMPERATURE SENSORÐ
3.0L................................. 25
IGNITION COILÐ3.OL.................... 24
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSORÐ3.0L........................ 24SPARK PLUG SERVICE................... 24
THROTTLE POSITION SENSOR............ 25
DISASSEMBLY AND ASSEMBLY
DISTRIBUTORÐ3.0L..................... 26
CLEANING AND INSPECTION
DISTRIBUTOR CAP...................... 26
DISTRIBUTOR ROTORÐ3.0L............... 27
SPECIFICATIONS
SPARK PLUG CABLE RESISTANCEÐ3.0L..... 27
SPARK PLUG........................... 27
TORQUE.............................. 27
DESCRIPTION AND OPERATION
FIRING ORDERÐ3.0L
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
The MAP sensor reacts to absolute pressure in the
intake manifold and provides an input voltage to the
Powertrain Control Module (PCM). As engine load
changes, manifold pressure varies. The changes in
engine load cause the MAP sensors resistance to
change. The change in MAP sensor resistance results
in a different input voltage to the PCM.
The input voltage level supplies the PCM with
information relating to ambient barometric pressure
during engine start-up (cranking) and engine load
while its operating. Based on MAP sensor voltage
and inputs from other sensors, the PCM adjusts
spark advance and the air-fuel mixture.
CAMSHAFT POSITION SENSOR
The PCM determines fuel injection synchronization
and cylinder identification from inputs provided by
the camshaft position sensor and crankshaft position
sensor. From the two inputs, the PCM determines
crankshaft position.
The 3.0L engine is equipped with a camshaft
driven mechanical distributor, containing a shaft
driven distributor rotor. The distributor is also
equipped with an internal camshaft position (fuel
sync) sensor (Fig. 1). This sensor provides fuel injec-
tion synchronization and cylinder identification to
the PCM.
The camshaft position sensor contains a hall effect
device callled a sync signal generator. This sync sig-
nal generator detects a rotating pulse ring (shutter)
on the distributor shaft. The pulse ring rotates 180
through the sync signal generator. Its signal is used
in conjunction with the crankshaft position sensor to
differentiate between fuel injection and spark events.
It is also used to synchronize the fuel injectors with
their respective cylinders.
When the leading edge of the shutter enters the
sync signal generator, the interruption of magnetic
field causes the voltage to switch high. This causes a
sync signal of approximately 5 volts.
When the trailing edge of the shutter leaves the
sync signal generator, the change of magnetic field
causes the sync signal voltage to switch low to 0
volts.
Since the shutter rotates at half crankshaft speed,
it may take 1 engine revolution during cranking for
the PCM to determine the position of piston number
6.
SPARK PLUG WIRE ROUTINGÐ3.0L ENGINE
NSIGNITION SYSTEM 8D - 23
INSTALLATION
(1) Reverse the above procedure for installation.
ENGINE COOLANT TEMPERATURE SENSORÐ3.0L
The sensor is installed next to the thermostat
housing (Fig. 3).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7- COOLING.
REMOVAL
(1) With the engine cold, drain coolant until level
drops below cylinder head. Refer to Group 7, Cooling
System.
(2) Disconnect coolant sensor electrical connector.
(3) Remove coolant sensor.
INSTALLATION
(1) Install coolant sensor. Tighten sensor to 7 N´m
(60 in. lbs.) torque.
(2) Attach electrical connector to sensor.
(3) Fill cooling system. Refer to Group 7, Cooling
System.
CRANKSHAFT POSITION SENSOR
REMOVAL
(1) Raise and support vehicle.
(2) Disconnect crankshaft position sensor electrical
connector from the wiring harness connector (Fig. 4).
(3) Remove crankshaft position sensor retaining
bolt.
(4) Pull crankshaft position sensor straight up out
of the transaxle housing.
INSTALLATION
NOTE: If the removed sensor is to be reinstalled,
clean off the old spacer on the sensor face. A NEW
SPACER must be attached to the sensor face before
installation. If the sensor is being replaced, confirm
that the paper spacer is attached to the face of the
new sensor (Fig. 5).
(1) Install sensor in transaxle and push sensor
down until contact is made with the drive plate.
While holding the sensor in this position, and install
and tighten the retaining bolt to 11.9 N´m (105 in.
lbs.) torque.
(2) Raise and support vehicle.
(3) Connect crankshaft position sensor electrical
connector to the wiring harness connector.
THROTTLE POSITION SENSOR
Refer to Group 14, Fuel Injection Section, for
Removal/Installation.
Fig. 3 Manifold Absolute Pressure Sensor
Fig. 4 Crankshaft Position Sensor Connector
Fig. 5 Crankshaft Position Sensor and Spacer
NSIGNITION SYSTEM 8D - 25
REMOVAL AND INSTALLATION (Continued)
3.3/3.8L ENGINE
INDEX
page page
DESCRIPTION AND OPERATION
FIRING ORDERÐ3.3/3.8L................. 28
REMOVAL AND INSTALLATION
CAMSHAFT POSITION SENSOR............ 31
CRANKSHAFT POSITION SENSOR.......... 30
ENGINE COOLANT TEMPERATURE SENSOR . . 32
IGNITION COIL......................... 30
KNOCK SENSORÐ3.3/3.8L................ 32
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR............................. 32SPARK PLUG CABLE SERVICEÐ3.3/3.8L
ENGINES............................ 28
SPARK PLUG SERVICEÐ3.3/3.8L ENGINES . . . 29
THROTTLE POSITION SENSOR............ 32
SPECIFICATIONS
IGNITION COIL......................... 33
SPARK PLUG CABLE RESISTANCEÐ3.3/3.8L . . 34
SPARK PLUG........................... 33
TORQUE.............................. 34
DESCRIPTION AND OPERATION
FIRING ORDERÐ3.3/3.8L
The firing order for 3.3L and 3.8L engines is 1-2-3-
4-5-6.
REMOVAL AND INSTALLATION
SPARK PLUG CABLE SERVICEÐ3.3/3.8L ENGINES
WARNING: The ignition cables should not be
removed while the engine is hot. This could cause
sever injury/burns and can cause damage to the
ignition cables.
The spark plug boot heat shield needs to be
installed correctly on the boot before being installed
on the engine (Fig. 1). If it is not installed correctly
engine misfire would occur.
Do not use pliers to pull the boot/heat shield
assembly from the spark plugs. This will damage the
shield assembly.
Spark plug boot heat shields must be replaced if
they are bent or damaged. It is extremely important
the shield is reinstalled correctly as shown. The bot-
tom of the spark plug heat shield must make contact
with the spark plug socket hex.
Firing OrderÐ3.3/3.8L
Fig. 1 Spark Plug Boot/Heat Shield Orientation
8D - 28 IGNITION SYSTEMNS