light CHEVROLET DYNASTY 1993 Manual Online

(4) Drive the vehicle 1 to 3 complete circles. The
CAL light will then go off, showing the compass is
calibrated. If the compass portion of the display:
² It does not display.
² Readings are not accurate after calibration.
² The vehicle may have too much magnetism for the
compass to be accurate.
² The compass circuitry is not working properly.
² Refer to Variance Procedure, Demagnetizing Pro-
cedure and/or Compass Diagnostics.
VARIANCE PROCEDURE
Variance is the difference between magnetic North
and geographic North. In some areas the difference
between magnetic and geographic North is great
enough to cause the compass to give false readings. If
this occurs, the variance must be set. To set the variance, depress and hold down both
the Comp/Temp button and the U.S./Metric button.
The display will go off and after 5 seconds the VAR
light will come on. Release both buttons. Using the
zone map (Fig. 5) to find your geographic location,
note the zone which, you are in. Press the U.S./Met-
ric button until the zone number appears on the dis-
play. Press the Comp/Temp button to enter your zone
number. Do not attach magnetic devices, such as magnetic
CB antennas to the vehicle roof, as they can cause
the compass to give false readings.
DEMAGNETIZING PROCEDURE
Every vehicle has its own magnetic field. This
magnetic field is created by the various processes a
steel roof goes through when the vehicle is built. A
magnetic field also can be created if the roof is sub-
jected to a magnet, example:
² Magnetic c.b. antenna
² Magnetic tipped screwdriver and etc.
If the roof becomes magnetized use a demagnetizer
tool 6029 to demagnetize the roof. In this demagnetizing procedure you will use the
demagnetizing tool to demagnetize the roof and
mounting screws in the overhead console. It is impor-
tant that you follow the instructions below exactly.
The mounting screws and the mounting brackets
around the compass area are steel, and therefore aid
in the demagnetizing of the roof panel. (1) Be sure the ignition switch is in the OFF posi-
tion before you begin the demagnetize procedure. (2) Open the sun glass compartment to gain access
to the overhead console mounting screws. (3) Plug the demagnetizing tool into a standard
110/115 volt AC outlet, keeping the demagnetizing
tool at least 12 inches away from the compass area
when plugging it in. (4) Slowly approach the console mounting screw
with the plastic coated tip of the tool for at least 2
seconds. (5) With the demagnetizing tool still energized,
slowly back it away from the screw until the tip is at
least 12 inches from the screw head. (6) After you have pulled at least 12 inches from
the last screw, remove the demagnetizing tool from
inside of the vehicle and disconnect it from the elec-
trical outlet. (7) Place an 8 1/2 X 11 inch piece of paper length-
wise on the roof of vehicle directly above compass.
The purpose of the paper is to protect the roof panel
from scratches and define the area to be demagne-
tized. (8) Plug in the demagnetizing tool, keeping it at
least 2 feet away from the compass unit. (9) Slowly approach the center of the roof panel at
the windshield with the demagnetizing tool plugged
in. (10) Contact the roof panel with the tip of the tool.
Using slow sweeping motions of 1/2 inch between
sweeps. Move the tool approximately 4 inches either
side of the centerline and at least 11 inch back from
the windshield. (11) With the demagnetizing tool still energized,
slowly back away from the roof panel until the tip is
at least 2 feet from the roof before unplugging the
tool.
Fig. 5 Variance Zone Map
Ä OVERHEAD CONSOLE 8C - 17

AP BODY INDEX
page page
Ambient Temperature Sensor Removal ........ 25
Compass Calibration ...................... 21
Compass Diagnostics ..................... 23
Compass Module Replacement .............. 25
Demagnetizing Procedure .................. 22 Map Reading Lamps Operation
.............. 21
Overhead Console Replacement ............. 25
Thermometer and Compass ................ 21
Variance Procedure ....................... 22
MAP READING LAMPS OPERATION
The map lamps are actuated by pressing on the
lens (Fig. 1).
LAMP REPLACEMENT
(1) Remove lens by inserting a screw driver or
knife blade into slot located along-side of lens. Once
screwdriver is inserted pry lens to the side and swing
down as it unhooks from housing edge. (2) Remove lamp by pulling straight down.
(3) Install new lamp by pushing firmly into recep-
tacle. (4) Snap lens into position taking care to orient
the tabs on the lens with the slots in the housing.
MAP LAMP TEST
(1) Press each lamp switch. Right hand switch
should light passenger lamp and left hand switch
should light drivers lamp. (2) If lamp does not illuminate check for a burned
out lamp, voltage, defective switch or faulty wiring.
THERMOMETER AND COMPASS
The ignition switch must be in the ON or ACCES-
SORY position before the temperature and compass
reading can be displayed. The Comp/Temp switch
turns the compass display on and off. The US/Metric
switch changes the temperature reading from Fahr-
enheit to Celsius (Fig. 2). When the vehicle is standing still, engine compart-
ment temperatures may be radiated to the tempera-
ture sensor. Therefore the most accurate ambient
temperature readings are displayed when the vehicle
is moving in a forward motion. When the ignition switch is in the ON position the
temperature display is updated every 5 minutes.
When the ignition switch is turned off the last dis-
played temperature reading stays in memory. When
the ignition switch is turned on again the thermom-
eter will display the memory temperature for 1
minute; then update the display to the actual tem-
perature within 5 minutes.
COMPASS CALIBRATION
Do not attempt to set the compass near large metal
objects, such as, other vehicles, large buildings, or
bridges. The compass unit automatically calibrates itself as
the vehicle is driven; therefore, no calibration should
be required. When the compass is first powered up,
the CAL light on the display should be on. The CAL
light will go off and the compass will be accurate af-
ter the vehicle completes one to three complete cir-
cles. If the vehicle's compass headings are inaccurate,
the compass also can be manually calibrated using
the following procedures: (1) Depress and hold down both the Comp/Temp
button and the U.S./Metric button. (2) The display will go off and after 5 seconds the
VAR light will come on. Continue to hold both but-
tons down. (3) In approximately 10 seconds, the CAL light
will come on. Release both buttons and the display
will show the heading and outside temperature. (4) Drive the vehicle 1 to 3 complete circles, with-
out turning ignition OFF. The CAL light will then
go off, showing the compass is calibrated.
Fig. 1 Overhead Console Lamp Replacement
Ä OVERHEAD CONSOLE 8C - 21

(5) The variation may need to be adjusted. The
variation is the difference between magnetic north
and true north. To set variation refer the to Varia-
tion Setting Procedure. If the compass portion of the display is not lit or
compass readings are not accurate after calibration.
The vehicle may have too much magnetism for the
compass to be accurate or the compass circuitry is
not working properly. Refer to Variance Procedure,
Demagnetizing Procedure and/or Compass Diagnos-
tics.
VARIANCE PROCEDURE
Variance is the difference between magnetic North
and geographic North. In some areas the difference
between magnetic and geographic North is great
enough to cause the compass to give false readings. If
this occurs, the variance must be set.
VARIANCE SETTING PROCEDURE
To set the variance, depress and hold down both
the Comp/Temp button and the U.S./Metric button.
The display will go off and after 5 seconds the VAR
light will come on. Release both buttons. Using the
zone map (Fig. 3) to find your geographic location,
note the zone which you are in. Press the U.S./Metric button until the zone number appears on the display.
Press the Comp/Temp button to enter your zone
number. Do not attach magnetic devices, such as magnetic
CB antennas to the vehicle roof, as they can cause
the compass to give false readings.
DEMAGNETIZING PROCEDURE
Every vehicle has its own magnetic field. This
magnetic field is created by the various processes a
steel roof goes through when the vehicle is built. A
magnetic field also can be created if the roof is sub-
jected to a magnet, example:
² Magnetic c.b. antenna
² Magnetic tipped screwdriver, etc.
If the roof becomes magnetized use a demagnetiz-
ing tool 6029 to demagnetize the roof. In this demagnetizing procedure you will use the
demagnetizing tool to demagnetize the roof and
mounting screws in the overhead console. It is impor-
tant that you follow the instructions below exactly.
The mounting screws and the mounting brackets
around the compass area are steel, and therefore aid
in the demagnetizing of the roof panel. (1) Be sure the ignition switch is in the OFF posi-
tion before you begin the demagnetize procedure. (2) Open the sun glass compartment to gain access
to the overhead console mounting screws.
Fig. 2 Overhead Console
8C - 22 OVERHEAD CONSOLE Ä

Light scaling of the terminals can be cleaned with
a sharp knife. If the terminals are heavily scaled, re-
place the distributor cap. A cap that is greasy, dirty or has a powder-like
substance on the inside should be cleaned with a so-
lution of warm water and a mild detergent. Scrub
the cap with a soft brush. Thoroughly rinse the cap
and dry it with a clean soft cloth.
ROTOR
Replace the rotor if it is cracked, the tip is exces-
sively burned or heavily scaled (Fig. 4). If the spring
terminal does not have adequate tension, replace the
rotor.
SPARK PLUG CABLES
Spark Plug cables are sometimes referred to as sec-
ondary ignition wires. They transfer electrical cur-
rent from the distributor to individual spark plugs at
each cylinder. 2.2L TBI, 2.5L TBI, 2.5L MPI, Turbo
III and 3.0L engines use resistance type cables. The
cables suppress radio frequency emissions from the
ignition system. Check the spark plug cable connections for good
contact at the coil and distributor cap towers and at
the spark plugs. Terminals should be fully seated.
The nipples and spark plug covers should be in good condition. Nipples should fit tightly on the coil and
distributor cap towers and spark plug cover should fit
tight around spark plug insulators. Loose cable connec-
tions can cause ignition malfunctions by permitting
water to enter the towers, corroding, and increasing
resistance. To maintain proper sealing at the ter-
minal connections, the connections should not
be broken unless testing indicates high resis-
tance, an open circuit or other damage.
CAUTION: Do not pull spark plug cables from dis-
tributor cap of four cylinder engines. The cables must
be released from inside the distributor cap (Fig. 5).
Clean high tension cables with a cloth moistened
with a non-flammable solvent and wipe dry. Check for
brittle or cracked insulation.
Fig. 2 Engine Firing OrderÐ2.2L TBI, 2.5L TBI, 2.5L MPI and Turbo III Engines
Fig. 3 Engine Firing OrderÐ3.0L Engine
Fig. 4 Rotor InspectionÐTypical
Fig. 5 Spark Plug Cable Removal/InstallationÐ2.2L and 2.5L TBI Engines
8D - 2 IGNITION SYSTEMS Ä

When testing secondary cables for punctures and
cracks with an oscilloscope follow the equipment
manufacturers instructions. If an oscilloscope is not available, secondary cables
can be tested as follows:
CAUTION: Do not leave any one spark plug cable
disconnected any longer than necessary during test-
ing. Excessive heat could damage the catalytic con-
verter. Total test time must not exceed ten minutes.
(a) With the engine not running, connect one end
of a test probe to a good ground. Use a probe made of
insulated wire with insulated alligator clips on each
end. (b) With engine running, move test probe along
entire length of all cables (approximately 0 to 1/8
inch gap). If punctures or cracks are present there
will be a noticeable spark jump from the faulty area
to the probe. Check the coil cable the same way.
Replace cracked, leaking or faulty cables.
When replacing cables, install the new high
tension cable and nipple assembly over cap or
coil tower. When entering the terminal into the
tower, push lightly, then pinch the large diam-
eter of nipple to release air trapped between the
nipple and tower. Continue pushing on the cable
and nipple until cables are properly seated in the
cap towers. A snap should be heard as terminal
goes into place. Use the same procedure to install cable in coil tower.
Wipe the spark plug insulator clean before reinstalling
cable and cover. Use the following procedure when removing the high
tension cable from the spark plug. First, remove the
cable from the retaining bracket. Then grasp the ter-
minal as close as possible to the spark plug. Rotate the
cover and pull the cable straight back. Pulling on the
cable itself will damage the conductor and termi-
nal connection. Do not use pliers and do not pull
the cable at an angle. Doing so will damage the
insulation, cable terminal or the spark plug in-
sulator. Wipe spark plug insulator clean before
reinstalling cable and cover. Resistance type cable is identified by the words
Electronic Suppression printed on the cable jacket.
Use an ohmmeter to check resistance type cable for
open circuits, loose terminals or high resistance as
follows: (a) Remove cable from spark plug.
(b) Lift distributor cap from distributor with
cables intact. Do not remove cables from cap. The
cables must be removed from the spark plugs. (c) Connect the ohmmeter between spark plug end
terminal and the corresponding electrode inside the
cap, make sure ohmmeter probes are in good contact.
Resistance should be within tolerance shown in the cable resistance chart. If resistance is
not within tolerance, remove cable at cap tower
and check the cable. If resistance is still not within
tolerance, replace cable assembly. Test all spark
plug cables in same manner.
To test coil to distributor cap high tension cable,
remove distributor cap with the cable intact. Do not
remove cable from the cap. Connect the ohmmeter
between center contact in the cap and remove the ca-
ble at coil tower and check cable resistance. If resis-
tance is not within tolerance, replace the cable.
SPARK PLUGS
Resistor spark plugs are used in all engines and
have resistance values of 6,000 to 20,000 ohms when
checked with at least a 1000 volt tester. Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. An iso-
lated plug displaying an abnormal condition indi-
cates that a problem exists in the corresponding
cylinder. Replace spark plugs at the intervals recom-
mended in Group O. Undamaged low milage spark plugs can be cleaned
and reused. Refer to the Spark Plug Condition sec-
tion of this group. After cleaning, file the center elec-
trode flat with a small point file or jewelers file.
Adjust the gap between the electrodes (Fig. 6) to the
dimensions specified in the chart at the end of this
section. Always tighten spark plugs to the specified torque.
Over tightening can cause distortion and change
spark plug gap. Tighten spark plugs to 28 N Im (20 ft.
lbs.) torque.
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. 7). 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. Spark plugs that have nor-
mal wear can usually be cleaned, have the electrodes
filed and regapped, and then reinstalled. Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
CABLE RESISTANCE CHART
Ä IGNITION SYSTEMS 8D - 3

pick-up (a Hall Effect device and magnet) through
which the shutter blades rotate. As the shutter
blades pass through the pick-up, they interrupt the
magnetic field. The Hall effect device in the pick-up
senses the change in the magnetic field and switches
on and off (which creates pulses), generating the in-
put signal to the PCM. The PCM calculates engine
speed through the number of pulses generated. On 2.5L MPI (flexible fuel AA-Body) engines, one
of the shutter blades has a window cut into it. The
PCM determines injector synchronization from the
window. Also, the PCM uses the input for detonation
control.
DISTRIBUTOR PICK-UPÐ3.0L ENGINE
The distributor pick-up provides two inputs to the
powertrain control module (PCM). From one input
the PCM determines RPM (engine speed). From the
other input it derives crankshaft position. The PCM
regulates injector synchronization and adjusts igni-
tion timing and engine speed based on these inputs. The distributor pick-up contains two signal gener-
ators. The pick-up unit consists of 2 light emitting
diodes (LED), 2 photo diodes, and a separate timing
disk. The timing disk contains two sets of slots. Each
set of slots rotates between a light emitting diode
and a photo diode (Fig. 17). The inner set contains 6
large slots, one for each cylinder. The outer set con-
tains several smaller slots. The outer set of slots on the rotating disk repre-
sents 2 degrees of crankshaft rotation. Up to 1200
engine RPM, the PCM uses the input from the outer
set of slots to increase ignition timing accuracy. The outer set of slots contains a 10 degree flat spot.
This area is not slotted (Fig. 17). The flat spot tells
the PCM that the next piston at TDC will be number
6. Each piston's position is referenced by one of the
six inner slots (Fig. 18). As each slot on the timing disk passes between the
diodes, they interrupt the beam from the light emit-
ting diode. This creates an alternating voltage in
each photo diode which is converted into on-off
pulses. The pulses are the input to the PCM. During cranking, the PCM cannot determine which
cylinder will be at TDC until the 10 degree flat spot
on the outer set of slots rotates through the optical
unit. Once the flat spot is detected, the PCM knows
piston number 6 will be the next piston at TDC. Since the disk rotates at half crankshaft speed, it
may take up to 2 engine revolutions during cranking
before the PCM determines the position of piston
number 6. For this reason the PCM energizes all six
injectors at the same time until it senses the position
of piston number 6.
COOLANT TEMPERATURE SENSOR
On 2.2L TBI, 2.5L TBI and 2.5L MPI engines, the
coolant temperature sensor is installed behind the
thermostat housing and ignition coil in the hot box
(Fig. 19). On 3.0L engines the sensor is located next
Fig. 16 DistributorÐ2.5L MPI (Flexible Fuel AA-Body)Fig. 17 Distributor Pick-upÐ3.0L Engine
Fig. 18 Inner and Outer Slots of Rotating DiskÐ3.0L Engine
Ä IGNITION SYSTEMS 8D - 7

to the thermostat housing (Fig. 20). The sensor pro-
vides an input voltage to the powertrain control mod-
ule (PCM). The sensor is a variable resistance
(thermistor) with a range of -40ÉF to 265ÉF. As cool-
ant temperature varies, the sensors resistance
changes, resulting in a different input voltage to the
PCM. The PCM contains different spark advance sched-
ules for cold and warm engine operation. The sched-
ules reduce engine emissions and improve
driveability. Because spark advance changes at dif-
ferent engine operating temperatures during warm-
up, all spark advance testing should be done with the
engine fully warmed. The PCM demands slightly richer air-fuel mixtures
and higher idle speeds until the engine reaches nor-
mal operating temperature. The coolant sensor input is also used for radiator
fan control.
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 causes the MAP sensors output voltage
to change. The change in MAP sensor output voltage
results in a different input voltage to the PCM. The input voltage level supplies the PCM with in-
formation relating to ambient barometric pressure
during engine start-up (cranking) and engine load
while its operating. The PCM uses this input along
with inputs from other sensors to adjust air-fuel mix-
ture. On 2.2L TBI, 2.5L TBI and 2.5L MPI (flexible fuel
AA-body) engines, the MAP sensor is mounted to the
dash panel (Fig. 21 or Fig. 22). On 3.0L engines, the
sensor is mounted to a bracket across from the dis-
tributor (Fig. 23). The sensor is connected to the
throttle body or intake manifold with a vacuum hose
and to the PCM electrically.
AUTO SHUTDOWN (ASD) RELAY AND FUEL PUMP
RELAY
The powertrain control module (PCM) operates the
auto shutdown (ASD) relay and fuel pump relay
through one ground path. The PCM operates the re-
lays by switching the ground path on and off. Both
relays turn on and off at the same time. The ASD relay connects battery voltage to the fuel
injector and ignition coil. The fuel pump relay con-
nects battery voltage to the fuel pump and oxygen
sensor heating element. The PCM turns the ground path off when the igni-
tion switch is in the Off position. Both relays are off.
When the ignition switch is in the On or Crank po-
sition, the PCM monitors the distributor pick-up sig-
Fig. 19 Coolant Temperature SensorÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 20 Coolant Temperature SensorÐ3.0L Engines
Fig. 21 MAP SensorÐ2.2L and 2.5L TBI Engines
8D - 8 IGNITION SYSTEMS Ä

(3) Inspect the spark plug condition. Refer to Spark
Plug Condition in this section.
SPARK PLUG GAP ADJUSTMENT
Check the spark plug gap with a gap gauge. If the
gap is not correct, adjust it by bending the ground
electrode (Fig. 6).
SPARK PLUG INSTALLATION
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading. (2) Tighten spark plugs to 28 N Im (20 ft. lbs.)
torque. (3) Install spark plug cables over spark plugs.
IDLE RPM TESTÐ2.5L AND 3.0L ENGINES
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING IDLE CHECK OR
ADJUSTMENT, OR ANY TESTS WITH A RUNNING
ENGINE.
Engine idle set rpmshould be recorded when the
vehicle is first brought into shop for testing. This
will assist in diagnosing complaints of engine stalling,
creeping and hard shifting on vehicles equipped with
automatic transaxles. Proceed to the Throttle Body Minimum Airflow pro-
cedures in Group 14.
IGNITION TIMING PROCEDUREÐ2.2L TBI, 2.5L
TBI, 2.5L MPI, AND 3.0L ENGINES
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING SETTING IGNITION
TIMING OR PERFORMING ANY TEST ON AN OPER-
ATING ENGINE.
Proper ignition timing is required to obtain optimum
engine performance. The distributor must be correctly
indexed to provide correct initial ignition timing. (1) Set the gearshift selector in park or neutral and
apply the parking brake. All lights and accessories
must be off. (2) If using a magnetic timing light, insert the
pickup probe into the open receptacle next to the
timing scale window. If a magnetic timing unit is not
available, use a conventional timing light connected to
the number one cylinder spark plug cable. Do not puncture cables, boots or nipples with
test probes. Always use proper adapters. Punc-
turing the spark plug cables with a probe will
damage the cables. The probe can separate the
conductor and cause high resistance. In addition
breaking the rubber insulation may permit sec-
ondary current to arc to ground. (3) Turn selector switch to the appropriate cylinder
position. (4) Start engine and run until operating tempera-
ture is obtained. (5) With the engine at normal operating tempera-
ture, connect the DRBII scan tool to the data link
connector (diagnostic connector). Access the State Dis-
play screen. Refer to the appropriate Powertrain Diag-
nostics Procedures Manual. If not using the DRBII
scan tool, disconnect the coolant temperature
sensor electrical connector. The electric radiator
fan will operate and the malfunction indicator lamp
(instrument panel Check Engine light) will turn on
after disconnecting the coolant sensor or starting the
DRBII scan tool procedure. (6) Aim Timing Light at timing scale (Fig. 7 or Fig.
8) or read magnetic timing unit. If flash occurs when
timing mark is before specified degree mark, timing is
advanced. To adjust, turn distributor housing in direc-
tion of rotor rotation. If flash occurs when timing mark is after specified
degree mark, timing is retarded. To adjust, turn dis-
tributor housing against direction of rotor rotation.
Refer to Vehicle Emission Control Information label for
correct timing specification. If timing is within 62É of
value specified on the label, proceed to step (8). If
outside specified tolerance, proceed to next step. (7) Loosen distributor hold-down arm screw
enough to rotate the distributor housing (Fig. 9 or
Fig. 6 Setting Spark Plug GapÐTypical
8D - 16 IGNITION SYSTEMS Ä

Fig. 10). Turn distributor housing to adjust timing.
Tighten the hold-down arm screw and recheck timing.
(8) Turn the engine off. Remove timing light or
magnetic timing unit and tachometer. If the coolant
temperature sensor was disconnected, connect the sen-
sor and erase fault codes using the Erase Fault
Code Mode on the DRBII scan tool.
DISTRIBUTORÐ2.2L TBI, 2.5L TBI AND 2.5L MPI
ENGINES
REMOVAL
(1) Disconnect distributor pick-up connector from
wiring harness connector (Fig. 11).
(2) Remove splash shield retaining screws (Fig.
12). (3) Remove splash shield (Fig. 12).
(4) Loosen distributor cap retaining screws (Fig.
13). (5) Lift cap off of distributor (Fig. 14).
(6) Rotate engine crankshaft until the distributor
rotor is pointing toward the cylinder block. Use this
as reference when reinstalling distributor. (7) Remove distributor hold-down screw.
(8) Carefully lift the distributor from the engine.
Fig. 10 Distributor HolddownÐ3.0L Engine
Fig. 11 Distributor Pickup ConnectorÐ2.5L Engine
Fig. 7 Timing ScaleÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 8 Timing ScaleÐ3.0L Engine
Fig. 9 Distributor HolddownÐ2.5L Engine
Ä IGNITION SYSTEMS 8D - 17

tance. The cables provide suppression of radio fre-
quency emissions from the ignition system.Check the spark plug cable connections for good
contact at the coil and distributor cap towers and at
the spark plugs. Terminals should be fully seated.
The nipples and spark plug covers should be in good
condition. Nipples should fit tightly on the coil and
distributor cap towers and spark plug cover should
fit tight around spark plug insulators. Loose cable
connections can cause ignition malfunctions by per-
mitting water to enter the towers, corroding, and in-
creasing resistance.
SPARK PLUGS
The 2.2L Turbo III, 3.3L and 3.8L engines use re-
sistor spark plugs. They have resistance values of
6,000 to 20,000 ohms when checked with at least a
1000 volt tester. Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. An iso-
lated plug displaying an abnormal condition indi-
cates that a problem exists in the corresponding
cylinder. Replace spark plugs at the intervals recom-
mended in Group O. Spark plugs that have low milage may be cleaned
and reused if not otherwise defective. Refer to the
Spark Plug Condition section of this group. After
cleaning, file the center electrode flat with a small
point file or jewelers file. Adjust the gap between the
electrodes (Fig. 8) to the dimensions specified in the
chart at the end of this section.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion and change
spark plug gap. Tighten 2.2L Turbo III, 3.3L and
3.8L spark plugs to 28 N Im (20 ft. lbs.) torque.
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. 9). 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. Spark plugs that have nor-
Fig. 6 Spark Plug Wire RoutingÐ3.3L and 3.8L Engines
Fig. 7 Powertrain Control Module (PCM)
Fig. 8 Setting Spark Plug Electrode GapÐTypical
8D - 26 IGNITION SYSTEMS Ä