1993 CHEVROLET DYNASTY oil

make sure that the spark plugs are firing. Inspect the
distributor rotor, cap, spark plug cables, and spark
plugs. If they are in proper working order, the ignition
system is not the reason why the engine will not start.
Inspect the fuel system and engine for proper opera-
tion.
FAILURE TO START TESTÐ2.5L TBI AND 3.0L
ENGINES
Before proceeding with this test make sure
Testing For Spark At Coil has been performed.
Failure to do this may lead to unnecessary diag-
nostic time and wrong test results.
WARNING: BE SURE TO APPLY PARKING BRAKE
AND/OR BLOCK WHEELS BEFORE PERFORMING
ANY TEST WITH THE ENGINE RUNNING.
(1) Battery voltage must be at least 12.4 volts to
perform test. (2) Crank the engine for 5 seconds while monitoring
the voltage at the coil positive (+) terminal (Fig. 2 or
Fig. 3). If the voltage remains near zero during the
entire period of cranking, refer to Group 14 for On-
Board Diagnostic checks. Also, refer to the DRBII scan
tool and the appropriate Powertrain Diagnostic Proce-
dures manual. These checks will help diagnose prob-
lems with the PCM and auto shutdown relay. (3) If voltage is at near-battery voltage and drops to
zero after 1-2 seconds of cranking, refer to On-Board
Diagnostic in Group 14. Also, refer to the DRBII scan
tool and the appropriate Powertrain Diagnostic Proce-
dures manual. These tests will help check the distribu-
tor reference pickup circuit to the PCM. (4) If voltage remains at near battery voltage during
the entire 5 seconds, with the key off,remove the
PCM 60-way connector. Check the 60-way connector
for any terminals that are pushed out or loose. (5) Remove the connector to coil (+) and connect a
jumper wire between battery (+) and coil (+). (6) Using the special jumper (Fig. 4), momentarily ground terminal #19 of the 60-way connector (Fig.
5). A spark should be generated when the ground is
removed.
(7) If spark is generated, replace the PCM.
(8) If no spark is seen, use the special jumper to
ground the coil (-) terminal directly. (9) If spark is produced, inspect wiring harness for
an open condition.
Fig. 2 Coil TerminalsÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 3 Coil TerminalsÐ3.0L Engine
Fig. 4 Special Jumper to Ground Coil Negative
Fig. 1 Checking for Spark
8D - 12 IGNITION SYSTEMS Ä

(10) If no spark is produced, replace the ignition coil.
POOR PERFORMANCE TEST
To prevent unnecessary diagnostic time and
possible incorrect results, the Testing For Spark
At Coil procedure should be performed before
this test.
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
THE WHEELS BEFORE PERFORMING ANY ENGINE
RUNNING TESTS.
Check and adjust basic timing (refer to the specifica-
tion section of this group and see service procedures).
COOLANT TEMPERATURE SENSOR TEST
(1) With key off, disconnect wire connector from
coolant temperature sensor (Fig. 6). (2) Connect one lead of ohmmeter to one terminal of
coolant temperature sensor. (3) Connect the other lead of ohmmeter to remaining
terminal of coolant temperature sensor. The ohmmeter
should read as follows;
² Engine/Sensor at normal operating temperature
around 200ÉF should read approximately 700 to 1,000
ohms.
² Engine/Sensor at room temperature around 70ÉF,
ohmmeter should read approximately 7,000 to 13,000
ohms. Refer to On Board Diagnostics in the General
Diagnosis section of Group 14. Also, refer to the
DRBII scan tool and the appropriate Powertrain
Diagnostic Procedures manual for additional
test procedures.
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST
Refer to the DRB II scan tool and appropriate Pow-
ertrain Diagnostic Procedures manual for further test
procedures.
Fig. 5 60-Way Electrical Connector, Powertrain con- trol module
Fig. 6 Coolant Temperature Sensor Test
Ä IGNITION SYSTEMS 8D - 13

2.2L TBI, 2.5L TBI, 2.5L MPI AND 3.0L IGNITION SYSTEMSÐSERVICE PROCEDURES
INDEX
page page
Coolant Temperature Sensor ................ 14
Distributor Pick-UpÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines ....................... 18
Distributor ServiceÐ3.0L Engine ............. 18
DistributorÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines .............................. 17
Idle RPM TestÐ2.5L and 3.0L Engines ........ 16
Ignition CoilÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines ....................... 14 Ignition CoilÐ3.0L Engines
................. 15
Ignition Timing ProcedureÐ2.2L TBI, 2.5L TBI, 2.5L MPI, and 3.0L Engines ............... 16
Manifold Absolute Pressure (MAP) Sensor ServiceÐ2.5L TBI and 3.0L Engines ........ 22
Powertrain Control Module (PCM) ............ 14
Spark Plug Service ....................... 15
POWERTRAIN CONTROL MODULE (PCM)
The powertrain control module (PCM) is located
next to the battery (Fig. 1).
REMOVAL
(1) Remove air cleaner duct or air cleaner assem-
bly. (2) Remove battery.
(3) Remove PCM mounting screws.
(4) Remove 60-way wiring connector from the
PCM. (5) Remove PCM.
INSTALLATION
(1) Connect 60-Way electrical connector to PCM
(Fig. 1). (2) Install PCM. Tighten mounting screws.
(3) Install battery.
(4) Install air cleaner duct or air cleaner assembly.
COOLANT TEMPERATURE SENSOR
On 2.2L TBI, 2.5L TBI and 2.5L MPI (flexible fuel
AA-Body) engines, the coolant temperature sensor is
located behind the ignition coil (Fig. 2). On 3.0L en-
gines the sensor is located next to the thermostat
housing (Fig. 3).
REMOVAL
(1) Drain cooling system until coolant level is below
coolant sensor. Refer to Group 7, Cooling System. (2) Disconnect electrical connector from sensor.
(3) Remove sensor from engine.
INSTALLATION
(1) Install coolant sensor. Tighten 2.2L TBI, 2.5L
TBI or 2.5L MPI engine coolant sensor to 28 N Im (20
ft. lbs.) torque. Tighten the 3.0L engine coolant sensor
to7N Im (60 in. lbs.) torque.
(2) Connect electrical connector to sensor.
(3) Fill cooling system. Refer to Group 7, Cooling
System.
IGNITION COILÐ2.2L TBI, 2.5L TBI AND 2.5L MPI
ENGINES
The ignition coil mounts to the thermostat housing
(Fig. 4).
Fig. 1 Powertrain control module (PCM)
Fig. 2 Coolant Temperature SensorÐ2.2 TBI, 2.5L TBI and 2.5L MPI Engines
8D - 14 IGNITION SYSTEMS Ä

REMOVAL
(1) Disconnect the coil to distributor ignition cable
(Fig. 4). (2) Disconnect the wiring harness connector from
the coil. (3) Remove ignition coil mounting screws.
INSTALLATION
(1) Install ignition coil onto the bracket. Tighten
the screws to 9.5 N Im (85 in. lbs.) torque. (2) Connect the wiring harness connector.
(3) Connect the coil to distributor ignition cable.
IGNITION COILÐ3.0L ENGINES
The ignition coil is located at the back of the intake
manifold (Fig. 5).
REMOVAL
(1) Remove air cleaner assembly.
(2) Disconnect ignition cable from coil.
(3) Disconnect wiring harness connector from coil.
(4) Remove coil mounting screws.
INSTALLATION
(1) Loosely install ignition coil on intake manifold.
Tighten the intake manifold fastener to 13 N Im(115
in. lbs.) torque. Tighten ignition coil bracket fasteners
to 10 N Im (96 in. lbs.) torque.
(2) Connect the wiring harness connector.
(3) Connect the coil to distributor ignition cable.
(4) Install the air cleaner assembly. Tighten the air
cleaner fasteners to 25 N Im (225 in. lbs.) torque.
SPARK PLUG SERVICE
When replacing the spark plug and coil cables, route
the cables correctly and secure them in the appropriate
retainers. Incorrectly routed cables can cause the radio
to reproduce ignition noise. It can also cause cross
ignition of the spark plugs or short circuit the cables to
ground.
SPARK PLUG REMOVAL
Always remove cables by grasping at boot, rotating
the boot 1/2 turn, and pulling straight back in a steady
motion. (1) Prior to removing the spark plug spray com-
pressed air around the spark plug hole and the area
around the spark plug. (2) Remove the spark plug using a quality socket
with a rubber or foam insert.
Fig. 3 Coolant Temperature SensorÐ3.0L Engine
Fig. 4 Ignition CoilÐ2.2L TBI, 2.5L TBI and 2.5L MPI Engines
Fig. 5 Ignition CoilÐ3.0L Engine
Ä IGNITION SYSTEMS 8D - 15

2.2L TURBO III, 3.3L AND 3.8L IGNITION SYSTEMÐSYSTEM OPERATION INDEX
page page
Auto Shutdown (ASD) Relay and Fuel Pump Relay ................................ 32
Camshaft Position Sensor .................. 28
Coolant Temperature Sensor ................ 32
Crankshaft Position Sensor ................. 29
General Information ....................... 24 Ignition Coil
............................. 31
Knock SensorÐTurbo III Engine ............. 32
Manifold Absolute Pressure (MAP) Sensor ..... 32
Powertrain Control Module (PCM) ............ 24
Spark Plug Cables ....................... 25
Spark Plugs ............................ 26
GENERAL INFORMATION
This section describes the ignition systems for 2.2L
Turbo III, 3.3L and 3.8L engines. The Fuel Injection sections of Group 14 describe On
Board Diagnostics. Group 0, Lubrication and Maintenance, contains
general maintenance information for ignition related
items. The Owner's Manual also contains maintenance
information. 2.2L Turbo III, 3.3L and 3.8L engines uses a
fixed ignition timing system. Basic ignition tim-
ing is not adjustable. All spark advance is deter-
mined by the powertrain control module (PCM). The ignition system does not use a distributor. The
system is referred to as the Direct Ignition System. The
system's three main components are the coil pack,
crankshaft position sensor, and camshaft position sen-
sor. The crankshaft and camshaft sensors are hall
effect devices. The camshaft position and crankshaft position sen-
sors generate pulses that are the inputs sent to the
PCM. The PCM interprets crankshaft and camshaft
position from these sensors. The PCM uses crankshaft
position sensor input to determine ignition timing. The
PCM determines injector sequence from the camshaft
position sensor. The camshaft position sensor determines when a
slot in the camshaft gear passes beneath it (Fig. 1 or
Fig. 2). The crankshaft position sensor determines
when a window in the drive plate passes under it
(Fig. 3 or Fig. 4). When metal aligns with the sensor,
voltage goes low (less than 0.5 volts). When a notch
aligns with the sensor, voltage spikes high (5.0
volts). As a group of notches pass under the sensor,
the voltage switches from low (metal) to high (notch)
then back to low.
FIRING ORDER
The firing order of the 2.2L Turbo III engine direct
ignition system is 1-3-4-2 (Fig. 5). The firing order of
the 3.3L and 3.8L engines direct ignition system is
1-2-3-4-5-6 (Fig. 6).
POWERTRAIN CONTROL MODULE (PCM)
The ignition system is regulated by the powertrain
control module (PCM) (Fig. 7). The PCM supplies
battery voltage to the ignition coil through the Auto
Shutdown (ASD) Relay. The PCM also controls
ground circuit for the ignition coil. By switching the
ground path for the coil on and off, the PCM adjusts
ignition timing to meet changing engine operating
conditions.
Fig. 37 Manifold Absolute Pressure (MAP) SensorÐ3.0L Engine
8D - 24 IGNITION SYSTEMS Ä

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

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)
for unleaded fuel. During combustion, fuel with MMT
may coat the entire tip of the spark plug with a rust
colored 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. 9). A dry, black deposit on one or
two plugs in a set may be caused by sticking valves or
defective spark plug cables. Cold (carbon) fouling of the
entire set may be caused by a clogged air cleaner. Cold fouling is normal after short operating periods.
The spark plugs do not reach a high enough operating
temperature during short operating periods.
WET FOULING A spark plug that is coated with excessive wet fuel or
oil is wet fouled. In older engines, wet fouling can be
caused by worn rings or excessive cylinder wear.
Break-in fouling of new engines may occur be-
fore normal oil control is achieved. In new or
recently overhauled engines, wet fouled spark
plugs can be usually be cleaned and reinstalled.
OIL OR ASH ENCRUSTED If one or more plugs are oil or oil ash encrusted,
engine oil is entering the combustion chambers (Fig.
10). Evaluate the engine to determine the cause.
HIGH SPEED MISS When replacing spark plugs because of a high speed
miss condition; wide open throttle operation
should be avoided for approximately 80 km (50 miles) after installation of new plugs.
This will
allow deposit shifting in the combustion chamber to
take place gradually and avoid plug destroying splash
fouling shortly after the plug change.
ELECTRODE GAP BRIDGING
Loose deposits in the combustion chamber can cause
electrode gap bridging. The deposits accumulate on the
spark plugs during continuous stop-and-go driving.
When the engine is suddenly subjected to a high torque
load, the deposits partially liquefy and bridge the gap
between the electrodes (Fig. 11). This short circuits the
electrodes. Spark plugs with electrode gap bridging can
be cleaned using standard procedures.
Fig. 9 Normal Operation and Cold (Carbon) Fouling
Fig. 10 Oil or Ash Encrusted
Fig. 11 Electrode Gap Bridging
Ä IGNITION SYSTEMS 8D - 27

tion timing from the crankshaft position sensor. Once
crankshaft position has been determined, the PCM
begins energizing the injectors in sequence.On Turbo III engines, the crankshaft position sensor
is located in the transaxle housing, below the throttle
body (Fig. 26). On 3.3L and 3.8L engines, the crank-
shaft position sensor is located in the transaxle hous-
ing (Fig. 27). The bottom of the sensor is positioned next to the
drive plate. The distance between the bottom of
sensor and the drive plate is critical to the op-
eration of the system. When servicing the crank-
shaft sensor, refer to the 3.3L Ignition
SystemÐService Procedures section in this
Group.IGNITION COIL
WARNING: THE DIRECT IGNITION SYSTEM GENER-
ATES APPROXIMATELY 40,000 VOLTS. PERSONAL
INJURY COULD RESULT FROM CONTACT WITH
THIS SYSTEM.
The 3.3L and 3.8L coil assembly consists of 3 coils
molded together (Fig. 28). The assembly is mounted
on the intake manifold. The 2.2L Turbo III coil as-
sembly consists of 2 coils molded together (Fig. 29).
The assembly is mounted at the front of the engine.
For all engines, the number of each coil appears on
the front of the coil pack.
High tension leads route to each cylinder from the
coil. The coil fires two spark plugs every power
stroke. One plug is the cylinder under compression,
the other cylinder fires on the exhaust stroke. The
PCM determines which of the coils to charge and fire
at the correct time. On 3.3L and 3.8L engines, coil one fires cylinders 1
and 4, coil two fires cylinders 2 and 5, coil three fires
cylinders three and six.
Fig. 28 Coil PackÐ2.2L Turbo III Engine
Fig. 29 Coil PackÐ3.3L and 3.8L Engines
Fig. 26 Crankshaft Position Sensor LocationÐTurbo III Engines
Fig. 27 Crankshaft Position Sensor LocationÐ3.3Land 3.8L Engines
Ä IGNITION SYSTEMS 8D - 31