1998 DODGE RAM 1500 Engine firing

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
SPECIFICATIONS
SPECIFICATIONS - TORQUE - IGNITION....3
ENGINE FIRING ORDER - 3.7L V-6.........4
ENGINE FIRING ORDER ± 4.7L V-8........4
FIRING ORDER / CABLE ROUTING ± 5.7L
V-8 ENGINE...........................4
SPARK PLUG CABLE RESISTANCE........4
SPARK PLUGS........................4
IGNITION COIL RESISTANCE - 3.7L V-6.....5
IGNITION COIL RESISTANCE - 4.7L V-8.....5
IGNITION COIL RESISTANCE - 5.7L V-8.....5
IGNITION TIMING......................5
AUTOMATIC SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............5
OPERATION
OPERATION - PCM OUTPUT.............5
OPERATION - ASD SENSE - PCM INPUT....5
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS........................5
REMOVAL.............................6
INSTALLATION..........................6
CAMSHAFT POSITION SENSOR
DESCRIPTION..........................7
OPERATION............................7
REMOVAL.............................9
INSTALLATION.........................10IGNITION COIL
DESCRIPTION.........................11
OPERATION...........................12
REMOVAL.............................13
INSTALLATION.........................14
KNOCK SENSOR
DESCRIPTION.........................14
OPERATION...........................14
REMOVAL.............................15
INSTALLATION.........................15
SPARK PLUG
DESCRIPTION.........................17
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................17
REMOVAL.............................19
CLEANING
CLEANING AND ADJUSTMENT...........20
INSTALLATION.........................20
IGNITION COIL CAPACITOR
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................21
INSTALLATION.........................21
SPARK PLUG CABLE
DESCRIPTION.........................21
OPERATION...........................21
REMOVAL.............................22
INSTALLATION.........................22
IGNITION CONTROL
DESCRIPTION
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
3.7L V-6 ENGINE
The 3.7L V-6 engine uses a separate ignition coil
for each cylinder. The one-piece coil bolts directly to
the cylinder head. Rubber boots seal the secondary
terminal ends of the coils to the top of all 6 spark
plugs. A separate electrical connector is used for each
coil.
Because of coil design, spark plug cables (second-
ary cables) are not used. A distributor is not used
with the 3.7L engine.
Two knock sensors (one for each cylinder bank) are
used to help control spark knock.The Auto Shutdown (ASD) relay provides battery
voltage to each ignition coil.
The ignition system consists of:
²6 Spark Plugs
²6 Separate Ignition Coils
²2 Knock Sensors
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position, 2 knock and
MAP Sensors
4.7L V-8 ENGINE
The 4.7L V-8 engine uses a separate ignition coil
for each cylinder. The one-piece coil bolts directly to
the cylinder head. Rubber boots seal the secondary
terminal ends of the coils to the top of all 8 spark
plugs. A separate electrical connector is used for each
coil.
DRIGNITION CONTROL 8I - 1

Because of coil design, spark plug cables (second-
ary cables) are not used. A distributor is not used
with the 4.7L engine.
Two knock sensors (one for each cylinder bank) are
used to help control spark knock.
The Auto Shutdown (ASD) relay provides battery
voltage to each ignition coil.
The ignition system consists of:
²8 Spark Plugs
²8 Separate Ignition Coils
²2 Knock Sensors
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position, 2 knock and
MAP Sensors
5.7L V-8 ENGINE
For additional information, also refer to Igni-
tion Coil Description and Operation.
The 5.7L V-8 engine is equipped with 16 spark
plugs. Two plugs are used for each cylinder. The 5.7L
is also equipped with 8 separate and independent
ignition coils. The one-piece coil bolts directly to the
cylinder head cover and attaches the coils secondary
output terminal directly to a spark plug using a rub-
ber boot seal. Each coil is also equipped with a sec-
ond output terminal. This second terminal connects a
conventional spark plug cable directly to a spark
plug on the opposite cylinder bank. A separate pri-
mary electrical connector is used for each coil.
Eight conventional spark plug cables are used with
the 5.7L. These cables connect a coil on one cylinder
bank, directly to a spark plug on the opposite cylin-
der bank. The cables are placed and routed in a spe-
cial plastic loom to keep them separated. This loom is
clipped to the intake manifold. To prevent a miss-
match of cables, a corresponding spark plug / coil
number is displayed on each plug cable: 1/6, 2/3, 4/7
and 5/8. These numbers can also be found on the top
of the intake manifold to the right of the throttle
body (Fig. 1).Two knock sensors (one for each cylinder bank) are
used to help control spark knock.
The 5.7L engine will not use a conventional distrib-
utor.
The ignition system consists of:
²16 Spark Plugs (2 per cylinder)
²8 Separate, Dual-Secondary Output, Ignition
Coils
²2 Knock Sensors
²8 Secondary Ignition Cables
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position, 2 knock and
MAP Sensors
Fig. 1 FIRING ORDER / CABLE ROUTING - 5.7L V-8
ENGINE
1 - TOP OF INTAKE MANIFOLD
2 - CYLINDER FIRING ORDER (IGNITION COIL NUMBER)
3 - CORRESPONDING SPARK PLUG NUMBER
8I - 2 IGNITION CONTROLDR
IGNITION CONTROL (Continued)

ENGINE FIRING ORDER - 3.7L V-6
1-6-5-4-3-2
ENGINE FIRING ORDER ± 4.7L V-8
FIRING ORDER / CABLE ROUTING ± 5.7L V-8
ENGINE
Eight conventional spark plug cables are used with
the 5.7L. These cables connect a coil on one cylinder
bank, directly to a spark plug on the opposite cylin-
der bank. The cables are placed and routed in a spe-
cial plastic loom to keep them separated. This loom is
clipped to the intake manifold. To prevent a miss-match of cables, a corresponding spark plug / coil
number is displayed on each plug cable: 1/6, 2/3, 4/7
and 5/8. These numbers can also be found on the top
of the intake manifold to the right of the throttle
body (Fig. 2).
SPARK PLUG CABLE RESISTANCE
MINIMUM MAXIMUM
250 Ohms Per Inch 1000 Ohms Per Inch
3000 Ohms Per Foot 12,000 Ohms Per Foot
SPARK PLUGS
ENGINE PLUG TYPE ELECTRODE GAP
3.7L V-6 ZFR6F - 11G (NGK) 1.1 (0.042 in.)
4.7L V-8 RC12MCC4 1.01 mm (.040 in.)
5.7L V-8 Champion - RE14MCC4 1.14 mm (.045 in.)
Fig. 2 FIRING ORDER / CABLE ROUTING - 5.7L V-8
ENGINE
1 - TOP OF INTAKE MANIFOLD
2 - CYLINDER FIRING ORDER (IGNITION COIL NUMBER)
3 - CORRESPONDING SPARK PLUG NUMBER
8I - 4 IGNITION CONTROLDR
IGNITION CONTROL (Continued)

Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 4.7L V-8 engine.
5.7L V-8
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
A ªwasted sparkº system is used on the 5.7L
engine combining paired, or dual-firing coils, and 2
spark plugs per cylinder. The coils and spark plugs
are connected with paired, secondary high-voltage
cables.
Each cylinder is equipped with 1 dual-output coil.
Meaning one coil mounts directly over one of the
dual spark plugs for 1 high-voltage output. A second
high-voltage output is supplied directly from the
same coil (using a plug cable) to one of the dual
spark plugs on a corresponding (paired) cylinder on
the opposite cylinder bank.
Each coil fires 2 spark plugs simultaneously on
each of the cylinder banks (one cylinder on compres-
sion stroke and one cylinder on exhaust stroke).
EXAMPLE :When the #1 cylinder is on compression
stroke and ready for spark, the #1 coil will fire one of
the dual spark plugs on the #1 cylinder (directly
below the coil). The other dual spark plug on the #1
cylinder will be fired by the #6 coil. At the same
time, the #1 coil will fire a ªwasted sparkº to one of
the dual spark plugs at the #6 cylinder as coil #6 also
fires a ªwasted sparkº to one of the dual spark plugs
at the #6 cylinder.
The firing order is paired at cylinders 1/6, 2/3, 4/7,
5/8. Basic cylinder firing order is 1±8±4±3±6±5±7±2.
Battery voltage is supplied to all of the ignition
coils positive terminals from the ASD relay. If the
PCM does not see a signal from the crankshaft and
camshaft sensors (indicating the ignition key is ON
but the engine is not running), it will shut down the
ASD circuit.
Base ignition timing is not adjustable on the
5.7L V-8 engine.By controlling the coil ground cir-
cuits, the PCM is able to set the base timing and
adjust the ignition timing advance. This is done to
meet changing engine operating conditions.
The PCM adjusts ignition timing based on inputs it
receives from:
²The engine coolant temperature sensor
²The crankshaft position sensor (engine speed)²The camshaft position sensor (crankshaft posi-
tion)
²The manifold absolute pressure (MAP) sensor
²The throttle position sensor
²Transmission gear selection
REMOVAL
3.7L V-6
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 16). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connec-
tor and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 16).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
4.7L V-8
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 17). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector (Fig. 17) from
coil by pushing downward on release lock on top of
connector and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
DRIGNITION CONTROL 8I - 13
IGNITION COIL (Continued)

REMOVAL
5.7L V-8
Spark plug cables on the 5.7L engine are paired on
cylinders 1/6, 2/3, 4/7 and 5/8. Before removing or
disconnecting any spark plug cables, note their orig-
inal position (Fig. 32). Remove cables one-at-a-time.
To prevent ignition crossfire, spark plug cables
MUSTbe placed in cable tray (routing loom) into
their original position. The cable retention clips (Fig.
32) must also be securly locked.
Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
If cable tray removal is necessary, release the 4
tray-to-manifold retention clips (Fig. 32).
INSTALLATION
Install cables into the proper engine cylinder firing
order sequence. Refer to Specifications.
When replacing the spark plug and coil cables,
route the cables correctly and secure them in the
proper retainers. Failure to route the cables properly
may cause the radio to reproduce ignition noise. It
could also cause cross-ignition of the plugs, or, may
short-circuit the cables to ground.
When installing new cables, make sure a positive
connection is made. A snap should be felt when a
good connection is made.
5.7L V-8
Refer to Spark Plug Cable Removal for
information.
Fig. 32 5.7L SPARK PLUG CABLE ROUTING
1 - #8 COIL-TO- #5 SPARK PLUG (MARKED 5/8) 7 - CABLE TRAY
2 - #5 COIL-TO- #8 SPARK PLUG (MARKED 5/8) 8 - CLIPS (SPARK PLUG CABLE-TO-TRAY- RETENTION)
3 - #7 COIL-TO- #4 SPARK PLUG (MARKED 4/7) 9 - #2 COIL-TO- #3 SPARK PLUG (MARKED 2/3)
4 - #3 COIL-TO- #2 SPARK PLUG (MARKED 2/3) 10 - #6 COIL-TO- #1 SPARK PLUG (MARKED 1/6)
5 - #1 COIL-TO- #6 SPARK PLUG (MARKED 1/6) 11 - #4 COIL-TO- #7 SPARK PLUG (MARKED 4/7)
6 - CLIPS (TRAY-TO-MANIFOLD RETENTION)
8I - 22 IGNITION CONTROLDR
SPARK PLUG CABLE (Continued)

ENGINE - 3.7L
DESCRIPTION
The 3.7 liter (226 CID) six-cylinder engine is an
90É single overhead camshaft engine (Fig. 1). The
cast iron cylinder block is made up of two different
components; the first component is the cylinder bore
and upper block, the second component is the bed-
plate that comprises the lower portion of the cylinderblock and houses the lower half of the crankshaft
main bearings. The cylinders are numbered from
front to rear with the left bank being numbered 1,3,
and 5 and the right bank being numbered 2,4, and 6.
The firing order is 1±6±5±4±3±2. The engine serial
number is located at the right front side of the
engine block
Fig. 1 3.7 L ENGINE
DRENGINE - 3.7L 9 - 3

(17) Connect the engine to body ground straps at
the left side of the cowl.
(18) Install the intake manifold.
(19) Install the engine oil dipstick tube.
(20) Install the power brake booster vacuum hose.
(21) Install the breather hoses.
(22) Install the PCV hose.
(23) Install the fuel rail.
(24) Install the coil over plugs.
(25) Connect the engine wiring harness at the fol-
lowing points:
²Intake air temperature (IAT) sensor
²Fuel Injectors
²Throttle Position (TPS) Switch
²Idle Air Control (IAC) Motor
²Engine Oil Pressure Switch
²Engine Coolant Temperature (ECT) Sensor
²Manifold Absolute Pressure MAP) Sensor
²Camshaft Position (CMP) Sensor
²Coil Over Plugs
²Crankshaft Position Sensor
(26) Reinstall the radiator/cooling module assem-
bly.
(27) Connect lower radiator hose.
(28) Connect upper radiator hose.
(29) Connect throttle and speed control cables.
(30) Install the heater hose assembly.
(31) Install coolant recovery bottle.
(32) Install the power steering pump.
(33) Install the generator.
(34) Install the A/C compressor.
(35) Install the drive belt.
(36) Install the fan shroud with the viscous fan
assembly.
(37) Install the radiator core support bracket.
(38) Install the air cleaner assembly.
(39) Refill the engine cooling system.
(40) Recharge the air conditioning.
(41) Install the hood.
(42) Check and fill engine oil.
(43) Connect the battery negative cable.
(44) Start the engine and check for leaks.SPECIFICATIONS
SPECIFICATIONS - 3.7L ENGINE
GENERAL SPECIFICATIONS
DESCRIPTION SPECIFICATION
Type 90É SOHC V6 12 Valve
Number of
Cylinders4
Firing Order 1-6-5-4-3-2
Lead Cylinder No. 1 Left Bank
Compression
Ratio9.1:1
Max. Variation
Between
Cylinders25%
Metric Standard
Displacement 3.7 Liters 226 Cubic
Inches
Bore 93.0 mm 3.66 in.
Stroke 90.8 mm 3.40 in.
Horsepower 210@5200 RPM
Torque 225ft. lbs.@4200 PRM
Compression
Pressure1172-1551 kPa 170-225 psi
CYLINDER BLOCK
DESCRIPTION SPECIFICATION
Metric Standard
Bore Diameter 93.0   .0075
mm3.6619   0.0003
in.
Out of Round
(MAX)0.076 mm 0.003 in.
Taper (MAX) 0.051 mm 0.002 in.
9 - 12 ENGINE - 3.7LDR
ENGINE - 3.7L (Continued)

AIR CLEANER ELEMENT
REMOVAL
Filter Element Only
Housing removal is not necessary for element (fil-
ter) replacement.
(1) Loosen clamp (Fig. 3) and disconnect air duct
at air cleaner cover.
(2) Pry over 4 spring clips (Fig. 3) from housing
cover (spring clips retain cover to housing).
(3) Release housing cover from locating tabs on
housing (Fig. 3) and remove cover.
(4) Remove air cleaner element (filter) from hous-
ing.
(5) Clean inside of housing before replacing ele-
ment.
Housing Assembly
(1) Loosen clamp (Fig. 3) and disconnect air duct
at air cleaner cover.
(2) Lift entire housing assembly from 4 locating
pins (Fig. 4).
INSTALLATION
(1) Install filter element into housing.
(2) Position housing cover into housing locating
tabs (Fig. 3).(3) Pry up 4 spring clips (Fig. 3) and lock cover to
housing.
(4) Install air duct to air cleaner cover and tighten
hose clamp to 3 N´m (30 in. lbs.) torque.
(5) If any other hose clamps were removed from
air intake system, tighten them to 3.4 N´m (30 in.
lbs.) torque.
(6) If any bolts were removed from air resonator
housing or air intake tubing, tighten them to 4.5 N´m
(40 in. lbs.) torque.
CYLINDER HEAD - LEFT
DIAGNOSIS AND TESTING - CYLINDER HEAD
GASKET
A cylinder head gasket leak can be located between
adjacent cylinders or between a cylinder and the
adjacent water jacket.
Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
²Loss of engine power
²Engine misfiring
²Poor fuel economy
Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
²Engine overheating
²Loss of coolant
Fig. 3 AIR CLEANER HOUSING COVER
1 - CLAMP
2 - AIR DUCT
3 - AIR CLEANER COVER
4 - LOCATING TABS
5 - CLIPS (4)
Fig. 4 AIR CLEANER HOUSING
1 - AIR CLEANER HOUSING ASSEMBLY
2 - LOCATING PINS (4)
DRENGINE - 3.7L 9 - 21