Crank DODGE RAM 1500 1998 2.G Workshop Manual

(6) Reconnect cable end to attachment stud. Then
with aid of a helper, observe movement of transmis-
sion throttle lever and lever on throttle body.
²If both levers move simultaneously from idle to
half-throttle and back to idle position, adjustment is
correct.
²If transmission throttle lever moves ahead of, or
lags behind throttle body lever, cable adjustment will
be necessary. Or, if throttle body lever prevents
transmission lever from returning to closed position,
cable adjustment will be necessary.
ADJUSTMENT PROCEDURE
(1) Turn ignition switch to OFF position.
(2) Remove air cleaner if necessary.
(3) Disconnect cable end from attachment stud.
Carefully slide cable off stud. Do not pry or pull
cable off.
(4) Verify that transmission throttle lever is in
fully closed position. Then be sure lever on throttle
body is at curb idle position.
(5) Pry the T.V. cable lock (A) into the UP position
(Fig. 226). This will unlock the cable and allow for
readjustment.
(6) Apply just enough tension on the T.V. cable (B)
to remove any slack in the cable.Pulling too tight
will cause the T.V. lever on the transmission to
move out of its idle position, which will result
in an incorrect T.V. cable adjustment.Slide the
sheath of the T.V. cable (D) back and forth until the
centerlines of the T.V. cable end (B) and the throttle
bell crank lever (C) are aligned within one millimeter
(1mm) (Fig. 226).
(7) While holding the T.V. cable in the set position
push the T.V. cable lock (A) into the down position
(Fig. 226). This will lock the present T.V. cable
adjustment.
NOTE: Be sure that as the cable is pulled forward
and centered on the throttle lever stud, the cable
housing moves smoothly with the cable. Due to the
angle at which the cable housing enters the spring
housing, the cable housing may bind slightly and
create an incorrect adjustment.
(8) Reconnect the T.V. cable (B) to the throttle
bellcrank lever (C).
(9) Check cable adjustment. Verify transmission
throttle lever and lever on throttle body move simul-
taneously.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 227) is a hydraulic
device that couples the engine crankshaft to the
transmission. The torque converter consists of an
outer shell with an internal turbine, a stator, an
overrunning clutch, an impeller and an electronically
applied converter clutch. The converter clutch pro-
vides reduced engine speed and greater fuel economy
when engaged. Clutch engagement also provides
reduced transmission fluid temperatures. The torque
converter hub drives the transmission oil (fluid)
pump.
The torque converter is a sealed, welded unit that
is not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid. If the fluid
is contaminated, flush the all transmission fluid
cooler(s) and lines.
Fig. 227 Torque Converter Assembly
1 - TURBINE
2 - IMPELLER
3 - HUB
4-STATOR
5 - FRONT COVER
6 - CONVERTER CLUTCH DISC
7 - DRIVE PLATE
DRAUTOMATIC TRANSMISSION - 48RE 21 - 255
THROTTLE VALVE CABLE (Continued)

(10) Remove the starter motor.
(11) Rotate crankshaft in clockwise direction until
converter bolts are accessible. Then remove bolts one
at a time. Rotate crankshaft with socket wrench on
dampener bolt.
(12) Disengage the output speed sensor connector
from the output speed sensor (Fig. 9).
(13) Disengage the input speed sensor connector
from the input speed sensor (Fig. 10).(14) Disengage the transmission solenoid/TRS
assembly connector from the transmission solenoid/
TRS assembly (Fig. 11).
(15) Disengage the line pressure sensor connector
from the line pressure sensor (Fig. 12).
Fig. 9 Disconnect Output Speed Sensor
1 - TRANSMISSION
2 - OUTPUT SPEED SENSOR
Fig. 10 Disconnect Input Speed Sensor
1 - TRANSMISSION
2 - INPUT SPEED SENSOR
Fig. 11 Disconnect Transmission Solenoid/TRS
Assembly
1 - TRANSMISSION
2 - TRANSMISSION SOLENOID/TRS ASSEMBLY
Fig. 12 Disconnect Line Pressure Sensor
1 - TRANSMISSION
2 - LINE PRESSURE SENSOR
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 319
AUTOMATIC TRANSMISSION - 45RFE/545RFE (Continued)

o-ring is properly installed and is free of any debris.
The hub must be smooth to avoid damaging pump
seal at installation.
(2) If a replacement transmission is being
installed, transfer any components necessary, such as
the manual shift lever and shift cable bracket, from
the original transmission onto the replacement trans-
mission.
(3) Lubricate oil pump seal lip with transmission
fluid.
(4) Align converter and oil pump.(5) Carefully insert converter in oil pump. Then
rotate converter back and forth until fully seated in
pump gears.
(6) Check converter seating with steel scale and
straightedge (Fig. 53). Surface of converter lugs
should be at least 13mm (1/2 in.) to rear of straight-
edge when converter is fully seated.
(7) Temporarily secure converter with C-clamp.
(8) Position transmission on jack and secure it
with chains.
(9) Check condition of converter driveplate.
Replace the plate if cracked, distorted or damaged.
Also be sure transmission dowel pins are seated
in engine block and protrude far enough to
hold transmission in alignment.
(10) Apply a light coating of MopartHigh Temp
Grease to the torque converter hub pocket in the rear
pocket of the engine's crankshaft.
(11) Raise transmission (Fig. 54) and align the
torque converter with the drive plate and transmis-
sion converter housing with the engine block.
(12) Move transmission forward. Then raise, lower
or tilt transmission to align the converter housing
with engine block dowels.
(13) Carefully work transmission forward and over
engine block dowels until converter hub is seated in
crankshaft. Verify that no wires, or the transmission
vent hose, have become trapped between the engine
block and the transmission.
(14) Install two bolts to attach the transmission to
the engine.
(15) Install remaining torque converter housing to
engine bolts. Tighten to 68 N´m (50 ft.lbs.).
Fig. 51 Install Primary Oil and Cooler Filters
1 - PRIMARY OIL FILTER
2 - COOLER RETURN FILTER
3 - COOLER RETURN FILTER BYPASS VALVE
4 - VALVE BODY
Fig. 52 Install Input, Output, and Line Pressure
Sensors
1 - OUTPUT SPEED SENSOR
2 - LINE PRESSURE SENSOR
3 - INPUT SPEED SENSOR
Fig. 53 Checking Torque Converter Seating - Typical
1 - SCALE
2 - STRAIGHTEDGE
21 - 334 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR
AUTOMATIC TRANSMISSION - 45RFE/545RFE (Continued)

SPECIFICATIONS
TRANSMISSION
GENERAL
Component Metric Inch
Output Shaft End Play 0.22-0.55
mm0.009-0.021
in.
Input Shaft End Play 0.46-0.89
mm0.018-0.035
in.
2C Clutch Pack
Clearance0.455-1.335
mm0.018-0.053
in.
4C Clutch Pack
Clearance0.770-1.390
mm0.030-0.055
in.
L/R Clutch Pack
Clearance1.00-1.74
mm0.039-0.069
in.
OD Clutch Pack
Clearance1.103-1.856
mm0.043-0.073
in.
Component Metric Inch
UD Clutch Pack
Clearance0.84-1.54
mm0.033-0.061
in.
Reverse Clutch Pack
Clearance0.81-1.24
mm0.032-0.049
in.
Recommended fluid MoparTAT F + 4
GEAR RATIOS
1ST 3.00:1
2ND 1.67:1
2ND Prime 1.50:1
3RD 1.0:1
4TH 0.75:1
5TH 0.67:1
REVERSE 3.00:1
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Fitting, cooler line at trans 17.5 - 155
Bolt, torque convertor 31 23 -
Bolt/nut, crossmember 68 50 -
Bolt, driveplate to crankshaft 75 55 -
Bolt, oil pan 11.8 - 105
Screw, primary fluid filter 4.5 - 40
Bolt, oil pump 28.2 - 250
Bolt, oil pump body to cover 4.5 - 40
Screw, plate to oil pump body 4.5 - 40
Bolt, valve body to case 11.8 - 105
Plug, pressure test port 5.1 - 45
Bolt, reaction shaft support 11.8 - 105
Screw, valve body to transfer plate 5.6 - 50
Screw, solenoid module to transfer plate 5.7 - 50
Screw, accumulator cover 8 - 70
Screw, detent spring 4.5 - 40
Bolt, input speed sensor 11.8 - 105
Bolt, output speed sensor 11.8 - 105
Bolt, line pressure sensor 11.8 - 105
Bolt, extension housing 54 40 -
Valve, cooler return filter bypass 4.5 - 40
Screw, manual valve cam retaining 4.5 - 40
Bolt, manual lever 28.2 - 250
21 - 358 AUTOMATIC TRANSMISSION - 45RFE/545RFEDR
AUTOMATIC TRANSMISSION - 45RFE/545RFE (Continued)

A solenoid can also be described by the method by
which it is controlled. Some of the possibilities
include variable force, pulse-width modulated, con-
stant ON, or duty cycle. The variable force and pulse-
width modulated versions utilize similar methods to
control the current flow through the solenoid to posi-
tion the solenoid plunger at a desired position some-
where between full ON and full OFF. The constant
ON and duty cycled versions control the voltage
across the solenoid to allow either full flow or no flow
through the solenoid's valve.
OPERATION
When an electrical current is applied to the sole-
noid coil, a magnetic field is created which produces
an attraction to the plunger, causing the plunger to
move and work against the spring pressure and the
load applied by the fluid the valve is controlling. The
plunger is normally directly attached to the valve
which it is to operate. When the current is removed
from the coil, the attraction is removed and the
plunger will return to its original position due to
spring pressure.
The plunger is made of a conductive material and
accomplishes this movement by providing a path for
the magnetic field to flow. By keeping the air gap
between the plunger and the coil to the minimum
necessary to allow free movement of the plunger, the
magnetic field is maximized.
TORQUE CONVERTER
DESCRIPTION
The torque converter (Fig. 117) is a hydraulic
device that couples the engine crankshaft to the
transmission. The torque converter consists of an
outer shell with an internal turbine, a stator, anoverrunning clutch, an impeller and an electronically
applied converter clutch. The converter clutch pro-
vides reduced engine speed and greater fuel economy
when engaged. Clutch engagement also provides
reduced transmission fluid temperatures. The torque
converter hub drives the transmission oil (fluid)
pump and contains an o-ring seal to better control oil
flow.
The torque converter is a sealed, welded unit that
is not repairable and is serviced as an assembly.
CAUTION: The torque converter must be replaced if
a transmission failure resulted in large amounts of
metal or fiber contamination in the fluid.
Fig. 117 Torque Converter Assembly
1 - TURBINE ASSEMBLY
2-STATOR
3 - CONVERTER HUB
4 - O-RING
5 - IMPELLER ASSEMBLY
6 - CONVERTER CLUTCH PISTON
7 - TURBINE HUB
DRAUTOMATIC TRANSMISSION - 45RFE/545RFE 21 - 399
SOLENOIDS (Continued)

ADJUSTMENTS
ADJUSTMENT
(1) Using a grease pencil or equivalent, mark the
position of the striker to aid in adjustment.
(2) Loosen the striker bolts.
(3) Change the striker position to adjust the rear
gap and flush measurement. (Refer to 23 - BODY/
BODY STRUCTURE/GAP AND FLUSH - SPECIFI-
CATIONS)
(4) Tighten the bolts to 28 N´m (21 ft. lbs.).
LOCK CYLINDER
REMOVAL
(1) Remove the exterior handle. (Refer to 23 -
BODY/DOOR - FRONT/EXTERIOR HANDLE -
REMOVAL)
(2) Remove the clip and remove the lock cylinder
lever and switch, if equipped.
(3) Remove the screw and remove the lock cylin-
der. (Fig. 11)
INSTALLATION
(1) Install the lock cylinder and install the screw.
(2) Install the lock cylinder switch, if equipped,
lever and retaining clip.
(3) Install the exterior handle. (Refer to 23 -
BODY/DOOR - FRONT/EXTERIOR HANDLE -
INSTALLATION)
TRIM PANEL
REMOVAL
(1) Remove the window crank, if equipped. (Fig.
13)
(2) Remove the interior handle. (Refer to 23 -
BODY/DOOR - FRONT/INSIDE HANDLE ACTUA-
TOR - REMOVAL)
(3) Remove the screws at the mirror flag and near
the inside handle. (Fig. 12)
CAUTION: Trim panel is attached to the door using
hooks molded into the panel. Do not pull the trim
panel straight off or damage to the panel and/or
power switch assembly may occur.
(4) Lift the trim panel up off the belt seal and
attachment hooks and separate the panel from the
door slightly.
(5) Disconnect the power window switch electrical
connector, if equipped, and remove the trim panel.
INSTALLATION
(1) Install the window switch into the trim panel,
if equipped.
(2) Position the trim panel onto the lower hooks
and connect the power window switch electrical con-
nector, if equipped.
(3) Position the remaining trim panel attachment
hooks into the door panel and seat the trim panel
into the belt seal fully.
(4) Install the screws near the inside handle and
at the mirror flag.
Fig. 11 LOCK CYLINDER
1 - LOCK CYLINDER
2 - EXTERIOR HANDLE
3 - SCREW
4 - LOCK SWITCH WIRE HARNESS
Fig. 12 TRIM PANEL ASSEMBLY
1 - SCREW INSERT (2)
2 - SCREWS (2)
3 - DOOR TRIM PANEL
4 - LOWER SCREWS (3)
5 - ATTACHMENT HOOKS
23 - 24 DOOR - FRONTDR
LATCH STRIKER (Continued)

(5) Install the interior handle. (Refer to 23 -
BODY/DOOR - FRONT/INSIDE HANDLE ACTUA-
TOR - INSTALLATION)
(6) Install the window crank, if equipped.
WATERDAM
REMOVAL
CAUTION: Do not allow the waterdam or adhesive
to become contaminated with dirt or other foreign
substances.
Do not damage the waterdam during removal and
installation.
If the waterdam becomes contaminated or dam-
aged, replace the waterdam.
(1) Remove the inside handle actuator. (Refer to 23
- BODY/DOOR - FRONT/INSIDE HANDLE ACTUA-
TOR - REMOVAL)
(2) Remove the speaker. (Refer to 8 - ELECTRI-
CAL/AUDIO/SPEAKER - REMOVAL)
(3) Separate the waterdam from the inner door
panel and off of the latch linkages.
INSTALLATION
CAUTION: Do not allow the waterdam or adhesive
to become contaminated with dirt or other foreign
substances.
Do not damage the waterdam during removal and
installation.
If the waterdam becomes contaminated or dam-
aged, replace the waterdam.(1) Position the wire harness and actuator rods
through the holes in the waterdam.
(2) Secure the waterdam to the inner door panel.
(3) Install the speaker. (Refer to 8 - ELECTRICAL/
AUDIO/SPEAKER - INSTALLATION)
(4) Install the inside handle actuator. (Refer to 23 -
BODY/DOOR - FRONT/INSIDE HANDLE ACTUA-
TOR - INSTALLATION)
WINDOW REGULATOR -
POWER
REMOVAL
(1) Remove the waterdam. (Refer to 23 - BODY/
DOOR - FRONT/WATERDAM - REMOVAL)
(2) Remove the window switch from the door trim
panel and reconnect it to the door harness.
(3) Raise the window to the position shown and
remove the nuts. (Fig. 14)
(4) Disengage the door glass from the regulator lift
plate and position into the full up position.
(5) Secure the glass in the up position using a
wood wedge or equivalent.
(6) Lower the regulator.
(7) Remove the stabilizer nuts.
(8) Remove the forward regulator bolt and loosen
the other two. (Fig. 15)
(9) Slide the regulator up and out of the keyhole
slots in the door panel.
(10) Disconnect the electrical connector and
remove the regulator.Fig. 13 WINDOW CRANK REMOVAL TOOL
1 - WINDOW CRANK REMOVAL TOOL
2 - WINDOW CRANK
Fig. 14 DOOR GLASS POSITIONING
1 - SIGHT WINDOW
2 - WIDOW REGULATOR
3 - SIGHT WINDOW
4 - REGULATOR STABILIZER
DRDOOR - FRONT 23 - 25
TRIM PANEL (Continued)

ADJUSTMENTS
ADJUSTMENT
(1) Locate access hole and remove the mylar tape
covering it. (Fig. 8)
(2) Insert a 5/32-inch hex-wrench through hole and
into adjustment screw. Loosen screw.
(3) Operate outside handle several times to release
any restriction because of mis-alignment.
(4) Tighten adjustment screw to 3 N´m (30 in.
lbs.).
(5) Test handle for proper operation.
LATCH STRIKER
REMOVAL
(1) Using a grease pencil or equivalent, mark the
position of the striker.
(2) Remove the bolts and remove the striker.
INSTALLATION
(1) Install the striker and install the bolts.
(2) Tighten the bolts to 28 N´m (21 ft. lbs.).
(3) Adjust the striker if needed. (Refer to 23 -
BODY/DOOR - FRONT/LATCH STRIKER - ADJUST-
MENTS)
ADJUSTMENTS
ADJUSTMENT
(1) Using a grease pencil or equivalent, mark the
position of the striker to aid in adjustment.
(2) Loosen the striker bolts.
(3) Change the striker position to adjust the rear
gap and flush measurement. (Refer to 23 - BODY/BODY STRUCTURE/GAP AND FLUSH - SPECIFI-
CATIONS)
(4) Tighten the bolts to 28 N´m (21 ft. lbs.).
TRIM PANEL
REMOVAL
(1) Remove the window crank, if equipped. (Fig.
10)
(2) Remove the interior handle. (Refer to 23 -
BODY/DOORS - REAR/INSIDE HANDLE ACTUA-
TOR - REMOVAL)
(3) Remove the screw near the inside handle. (Fig.
9)
CAUTION: Trim panel is attached to the door using
hooks molded into the panel. Do not pull the trim
panel straight off or damage to the panel and/or
power switch assembly may occur.
(4) Lift the trim panel up off the belt seal and
attachment hooks and separate the panel from the
door slightly.
(5) Disconnect the power window switch electrical
connector, if equipped, and remove the trim panel.
INSTALLATION
(1) Position the trim panel onto the lower hooks
and connect the power window switch electrical con-
nector, if equipped.
(2) Position the remaining trim panel attachment
hooks into the door panel and seat the trim panel
into the belt seal fully.
(3) Install the screw near the inside handle.
Fig. 8 LATCH ADJUSTMENT SCREW - TYPICAL
1 - DOOR LATCH
2 - MYLAR TAPE
3 - ADJUSTMENT SCREW
Fig. 9 TRIM PANEL
1 - DOOR
2 - ELECTRICAL CONNECTOR
3 - ATTACHMENT HOOKS
4 - SCREW
5 - TRIM PANEL
DRDOORS - REAR 23 - 33
LATCH (Continued)

(4) Install the interior handle. (Refer to 23 -
BODY/DOORS - REAR/INSIDE HANDLE ACTUA-
TOR - INSTALLATION)
(5) Install the window crank, if equipped.
WATERDAM
REMOVAL
(1) Remove the inside handle actuator. (Refer to 23
- BODY/DOORS - REAR/INSIDE HANDLE ACTUA-
TOR - REMOVAL)
(2) Remove the speaker. (Refer to 8 - ELECTRI-
CAL/AUDIO/SPEAKER - REMOVAL)
(3) Separate the waterdam from the inner door
panel and off of the latch linkages.
INSTALLATION
(1) Position the wire harness and actuator rods
through the holes in the waterdam.
(2) Secure the waterdam to the inner door panel.
(3) Install the speaker. (Refer to 8 - ELECTRICAL/
AUDIO/SPEAKER - INSTALLATION)
(4) Install the inside handle actuator. (Refer to 23 -
BODY/DOORS - REAR/INSIDE HANDLE ACTUA-
TOR - INSTALLATION)
WINDOW REGULATOR -
POWER
REMOVAL
(1) Remove the waterdam. (Refer to 23 - BODY/
DOORS - REAR/WATERDAM - REMOVAL)
(2) Remove the window switch from the door trim
panel and reconnect it to the door wire harness.(3) Raise the window to the position shown and
remove the two nuts attaching the glass to the win-
dow regulator. (Fig. 11)
(4) Remove the stabilizer nut.
(5) Disengage the door glass from the regulator lift
plate and position into the full up position.
(6) Secure the glass in the up position using a
wood wedge or equivalent.
(7) Lower the regulator.
(8) Disconnect the electrical connector. (Fig. 12)
(9) Remove the lower regulator bolt and loosen the
upper two. (Fig. 12)
(10) Slide the regulator up and out of the keyhole
slots in the door panel.
(11) Remove the regulator through the hole in the
inner door panel.
INSTALLATION
(1) Install the regulator through the hole in the
inner door panel.
(2) Position the regulator bolts into the keyhole
slots and slide into place.
(3) Install the lower regulator bolt and tighten all
three to 10 N´m (89 in. lbs.).
(4) Connect the electrical connector.
(5) Position the stabilizer, install the nut and
tighten to 10 N´m (89 in. lbs.).
(6) Raise the regulator to the position shown in
(Fig. 11).
(7) Remove the glass support and connect to the
regulator lift plate.
(8) Install the glass nuts and tighten to 10 N´m
(89 in. lbs.).
(9) Disconnect the window switch and install into
the door trim panel.
Fig. 10 WINDOW CRANK REMOVAL TOOL
1 - WINDOW CRANK REMOVAL TOOL
2 - WINDOW CRANK
Fig. 11 GLASS POSITIONING
1 - SIGHT WINDOW
2 - STABILIZER NUT
3 - GLASS LIFT PLATE
23 - 34 DOORS - REARDR
TRIM PANEL (Continued)

Immediately after a cold start, between predeter-
mined temperature thresholds limits, the three port
solenoid is briefly energized. This initializes the
pump by drawing air into the pump cavity and also
closes the vent seal. During non test conditions the
vent seal is held open by the pump diaphragm
assembly which pushes it open at the full travel posi-
tion. The vent seal will remain closed while the
pump is cycling due to the reed switch triggering of
the three port solenoid that prevents the diaphragm
assembly from reaching full travel. After the brief
initialization period, the solenoid is de-energized
allowing atmospheric pressure to enter the pump
cavity, thus permitting the spring to drive the dia-
phragm which forces air out of the pump cavity and
into the vent system. When the solenoid is energized
and de energized, the cycle is repeated creating flow
in typical diaphragm pump fashion. The pump is con-
trolled in 2 modes:
Pump Mode: The pump is cycled at a fixed rate to
achieve a rapid pressure build in order to shorten the
overall test length.
Test Mode: The solenoid is energized with a fixed
duration pulse. Subsequent fixed pulses occur when
the diaphragm reaches the Switch closure point.
The spring in the pump is set so that the system
will achieve an equalized pressure of about 7.5º H20.
The cycle rate of pump strokes is quite rapid as the
system begins to pump up to this pressure. As the
pressure increases, the cycle rate starts to drop off. If
there is no leak in the system, the pump would even-
tually stop pumping at the equalized pressure. If
there is a leak, it will continue to pump at a rate rep-
resentative of the flow characteristic of the size of the
leak. From this information we can determine if the
leak is larger than the required detection limit (cur-
rently set at .040º orifice by CARB). If a leak is
revealed during the leak test portion of the test, the
test is terminated at the end of the test mode and no
further system checks will be performed.
After passing the leak detection phase of the test,
system pressure is maintained by turning on the
LDP's solenoid until the purge system is activated.
Purge activation in effect creates a leak. The cycle
rate is again interrogated and when it increases due
to the flow through the purge system, the leak check
portion of the diagnostic is complete.
The canister vent valve will unseal the system
after completion of the test sequence as the pump
diaphragm assembly moves to the full travel position.
Evaporative system functionality will be verified by
using the stricter evap purge flow monitor. At an
appropriate warm idle the LDP will be energized to
seal the canister vent. The purge flow will be clocked
up from some small value in an attempt to see a
shift in the 02 control system. If fuel vapor, indicatedby a shift in the 02 control, is present the test is
passed. If not, it is assumed that the purge system is
not functioning in some respect. The LDP is again
turned off and the test is ended.
MISFIRE MONITOR
Excessive engine misfire results in increased cata-
lyst temperature and causes an increase in HC emis-
sions. Severe misfires could cause catalyst damage.
To prevent catalytic convertor damage, the PCM
monitors engine misfire.
The Powertrain Control Module (PCM) monitors
for misfire during most engine operating conditions
(positive torque) by looking at changes in the crank-
shaft speed. If a misfire occurs the speed of the
crankshaft will vary more than normal.
FUEL SYSTEM MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
reduce the emission of hydrocarbons, oxides of nitro-
gen and carbon monoxide. The catalyst works best
when the Air Fuel (A/F) ratio is at or near the opti-
mum of 14.7 to 1.
The PCM is programmed to maintain the optimum
air/fuel ratio of 14.7 to 1. This is done by making
short term corrections in the fuel injector pulse width
based on the O2S sensor output. The programmed
memory acts as a self calibration tool that the engine
controller uses to compensate for variations in engine
specifications, sensor tolerances and engine fatigue
over the life span of the engine. By monitoring the
actual fuel-air ratio with the O2S sensor (short term)
and multiplying that with the program long-term
(adaptive) memory and comparing that to the limit,
it can be determined whether it will pass an emis-
sions test. If a malfunction occurs such that the PCM
cannot maintain the optimum A/F ratio, then the
MIL will be illuminated.
CATALYST MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
reduce the emission of hydrocarbons, oxides of nitro-
gen and carbon monoxide.
Normal vehicle miles or engine misfire can cause a
catalyst to decay. This can increase vehicle emissions
and deteriorate engine performance, driveability and
fuel economy.
The catalyst monitor uses dual oxygen sensors
(O2S's) to monitor the efficiency of the converter. The
dual O2S's sensor strategy is based on the fact that
as a catalyst deteriorates, its oxygen storage capacity
and its efficiency are both reduced. By monitoring
the oxygen storage capacity of a catalyst, its effi-
ciency can be indirectly calculated. The upstream
DREMISSIONS CONTROL 25 - 3
EMISSIONS CONTROL (Continued)