injector DODGE RAM 2002 Service Manual Online

lines before opening up any fuel system component.
Always cover or cap any open fuel connections before
a fuel system repair is performed.
Each fuel injector connector tube contains an edge
filter (Fig. 13) that breaks up small contaminants
that enter the injector. The edge filter uses the injec-
tors pulsating high-pressure to break up most parti-
cles so they are small enough to pass through the
injector.The edge filters are not a substitute for
proper cleaning and covering of all fuel system
components during repair.
The bottom of each fuel injector is sealed to the
cylinder head with a1.5mmthick copper shim (gas-
ket) (Fig. 12). The correct thickness shim must
always be re-installed after removing an injector.
Fuel pressure in the injector circuit decreases after
injection. The injector needle valve is immediately
closed by the needle valve spring and fuel flow into
the combustion chamber is stopped. Exhaust gases
are prevented from entering the injector nozzle by
the needle valve.
DIAGNOSIS AND TESTINGÐFUEL INJECTOR
TEST
The fuel injectors are located in the top of the cyl-
inder head between the intake/exhaust valves (Fig.
14).A leaking fuel injector can cause fuel knock, poor
performance, black smoke, poor fuel economy and
rough engine idle. If fuel injector needle valve does
not operate properly, engine may misfire and produce
low power.
A leak in injection pump-to-injector high-pressure
fuel line can cause many of same symptoms as mal-
functioning injector. Inspect for leaks in high-pres-
sure lines before checking for malfunctioning fuel
injector.
WARNING: THE INJECTION PUMP SUPPLIES HIGH-
PRESSURE FUEL OF UP TO APPROXIMATELY
120,000 kPa (17,400 psi) TO EACH INDIVIDUAL
INJECTOR THROUGH HIGH-PRESSURE LINES.
FUEL UNDER THIS AMOUNT OF PRESSURE CAN
PENETRATE SKIN AND CAUSE PERSONAL INJURY.
WEAR SAFETY GOGGLES AND ADEQUATE PRO-
TECTIVE CLOTHING. AVOID CONTACT WITH FUEL
SPRAY WHEN BLEEDING HIGH-PRESSURE FUEL
LINES.
WARNING: DO NOT BLEED AIR FROM FUEL SYS-
TEM OF A HOT ENGINE. DO NOT ALLOW FUEL TO
SPRAY ONTO EXHAUST MANIFOLD WHEN BLEED-
ING AIR FROM FUEL SYSTEM.
(1) To determine which fuel injector is malfunc-
tioning, run engine and isolate each cylinder using
DRB scan tool.The DRB scan tool lists the injec-
tor firing order in both cylinder numerical
order (1±2±3±4±5±6), and actual firing order
(1±5±3±6±2±4).
Fig. 14 Fuel Injector Connections
1 - CONNECTOR
2 - O-RING
3 - FERRULE
4 - FITTING
5 - FUEL LINE
6 - INJECTOR
Fig. 15 Inspecting Injector Operation
1 - HIGH-PRESSURE FUEL LINE
BR/BEFUEL INJECTION - DIESEL 14 - 99
FUEL INJECTOR (Continued)

(2) Note RPM drop for each cylinder. As an alter-
native, loosen high-pressure fuel line fitting at fuel
injector connector tube (Fig. 15). Listen for a change
in engine speed. After testing, tighten line fitting to
40 N´m (30 ft. lbs.) torque. If engine speed drops,
injector was operating normally. If engine speed
remains same, injector may be malfunctioning. Test
all injectors in same manner one at a time.(3) Once injector has been found to be malfunc-
tioning, remove it from engine and test it. Refer to
Fuel Injector Removal/Installation.
WARNING: FUEL INJECTOR TESTERS CAN
DEVELOP EXTREMELY HIGH PRESSURES. FUEL
UNDER THIS AMOUNT OF PRESSURE CAN PENE-
TRATE SKIN AND CAUSE PERSONAL INJURY.
WEAR SAFETY GOGGLES AND ADEQUATE PRO-
TECTIVE CLOTHING. AVOID CONTACT WITH FUEL
SPRAY WHEN OPERATING INJECTOR TESTOR.
(4)
After injector has been removed, obtain bench-
mount fuel injector tester OTCt(SPXt) part number
4210 (Fig. 16) (or equivalent). Install Special Tool num-
ber 8301 (Fuel Injector Adapter) to 4210 tester. Install
fuel injector into 8301 adapter. Be sure tip of adapter
tool 8301 is aligned to inlet hole at side of injector (Fig.
17) before tightening tool. Tighten tool 8301 to injector.
Position container below injector before testing.
(5) Refer to operating instructions supplied with
pressure tester for procedures.
(a) Check opening pressure or ªpopº pressure.
Pressure should be approximately 31,026 kPa (310
bars) or (4500 psi   250 psi). If fuel injector needle
valve is opening (popping) too early or too late,
replace injector.
(b) Perform a leak-down test on injector. Apply
pressure with injector tester. The injector should
not leak (drip) fuel with pressure at approximately
20 bars (291 psi) lower than pop pressure.
(c) Operate tester lever quickly several times to
check injector spray pattern. Verify fuel is spraying
from each injector nozzle hole. Injector should also
spray evenly from each nozzle hole.
(d) Pay attention to size and shape of spray
plumes. They should all be equal. If possible, com-
pare spray pattern to that of a new fuel injector
with same part number. Checking each plume for
consistency is an excellent indicator of injector per-
formance. Even if only one nozzle hole is plugged,
significant performance problems could result.
(e) Look for burrs on injector inlet.
(f) Check nozzle holes for hole erosion or plug-
ging.
(g) Inspect end of nozzle for burrs or rough
machine marks.
(h) Look for cracks at nozzle end.
(i) Check nozzle color for signs of overheating.
Overheating will cause nozzle to turn a dark yel-
low/tan or blue (depending on overheating temper-
ature).
(j)
Look at end of injector tube where it meets
injector. A small, shiny band should be seen at this
point. The band should have a consistent thickness.
If not, injector could be leaking into fuel return.
(k)If any of these conditions occur, replace injector.
Fig. 16 Fuel
1 - FUEL INJECTOR
2 - ADAPTOR TOOL 8301
3 - POP PRESSURE TESTER
Fig. 17 Installing Injector to Adaptor Tool 8301
1 - ADAPTOR TOOL 8301
2 - TIP
3 - FUEL INJECTOR
4 - INLET AT SIDE OF INJECTOR
14 - 100 FUEL INJECTION - DIESELBR/BE
FUEL INJECTOR (Continued)

REMOVAL
The fuel injectors are located in the top of the cyl-
inder head between the intake/exhaust valves (Fig.
18).
CAUTION: Refer to Cleaning Fuel System Parts.
(1) Disconnect both negative battery cables from
both batteries. Cover and isolate ends of cables.
Each fuel injector is connected to each high-pres-
sure fuel line with a steel connector tube (Fig. 19).
This steel connector is positioned into cylinder head
and sealed with an o-ring. The connectors are con-
nected to high-pressure fuel lines with fittings (Fig.
19).
(2) If injector at #1 or #2 cylinder is being
removed, intake manifold air heater assembly must
be removed. Refer to Intake Manifold Air Heater
Removal/Installation.
(3) If injector at #5 cylinder is being removed,
remove engine lifting bracket (2 bolts).
(4) Thoroughly clean area around injector and
injector high-pressure lines before removal.
(5) Remove necessary high-pressure fuel lines.
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/
FUEL LINES - REMOVAL).Do not bend any high-
pressure fuel line to gain access to fuel injector.
Cover or cap any open fuel connections.
(6) Remove valve cover (Refer to 9 - ENGINE/CYL-
INDER HEAD/CYLINDER HEAD COVER(S) -
REMOVAL).
(7) Thread Special Tool 8324 (Fuel Injector Con-
nector Tube Remover) onto end of injector connector
tube (Fig. 20).
(8) Pull injector connector tube from cylinder head.
The injector connector tube must be removed
before attempting to remove fuel injector or
serious damage to fuel injector and tube will
result.
(9) Remove and discard old o-ring (Fig. 19) from
injector connector tube.
(10) Remove fuel injector hold down clamp bolt at
front end of clamp (Fig. 18).Do not loosen or
remove special (2 shouldered) bolt at rear end
of clamp.Remove injector clamp by sliding it from
shoulders on rear clamp bolt.
(11) Thread rod from Special Tool number 8318
(Fuel Injector Remover) into top of fuel injector (Fig.
21).
(12) Tighten nut on 8318 tool to pull (remove) fuel
injector from cylinder head.
(13) Remove and discard old o-ring from fuel injec-
tor.
(14) Remove and discard copper sealing washer
(shim) (Fig. 22) from bottom of injector.If coppersealing washer has remained in cylinder head,
it must be removed.
Fig. 18 Fuel Injector Location
1 - CLAMP
2 - FUEL INJECTOR
3 - BORED HOLE
4 - SHIM
5 - BOLTS
Fig. 19 Fuel Injector Connections
1 - CONNECTOR
2 - O-RING
3 - FERRULE
4 - FITTING
5 - FUEL LINE
6 - INJECTOR
BR/BEFUEL INJECTION - DIESEL 14 - 101
FUEL INJECTOR (Continued)

INSTALLATION
The fuel injectors are located in the top of the cyl-
inder head between the intake/exhaust valves (Fig.
18).
(1) Inspect fuel injector.
(a) If necessary, perform pressure test of injector.
Refer to Fuel Injector Testing.
(b) Look for burrs on injector inlet.(c) Check nozzle holes for hole erosion or plug-
ging.
(d) Inspect end of nozzle for burrs or rough
machine marks.
(e) Look for cracks at nozzle end.
(f) Check nozzle color for signs of overheating.
Overheating will cause nozzle to turn a dark yel-
low/tan or blue (depending on overheating temper-
ature).
Fig. 20 Fuel Injector Connector Tube Removal
1 - FUEL INJECTOR CONNECTOR TUBE
2 - SPECIAL TOOL 8324
3 - CYLINDER HEAD
Fig. 21 Fuel Injector Removal
1 - FUEL INJECTOR REMOVAL TOOL 8318
2 - TIGHTEN NUT FOR INJECTOR TERMINAL
3 - THREAD INTO INJECTOR
Fig. 22 Fuel Injector Sealing Washer (Shim)
Location
1 - FUEL INJECTOR
2 - COPPER SEALING WASHER (SHIM)
Fig. 23 Measuring Injector Sealing Washer (Shim)
1 - SHIM
14 - 102 FUEL INJECTION - DIESELBR/BE
FUEL INJECTOR (Continued)

(g) If any of these conditions occur, replace injec-
tor.
(2) Thoroughly clean fuel injector cylinder head
bore with special Cummins wire brush tool or equiv-
alent (Fig. 24). Blow out bore hole with compressed
air.
(3) The bottom of fuel injector is sealed to cylinder
head bore with a copper sealing washer (shim) of a
certain thickness. A new shim with correct thickness
must always be re-installed after removing injector.
Measure thickness of injector shim (Fig. 23).Shim
Thickness: 1.5 mm (.060º)
(4) Install new shim (washer) to bottom of injector
(Fig. 22). Apply light coating of clean engine oil to
washer. This will keep washer in place during instal-
lation.
(5) Install new o-ring to fuel injector. Apply small
amount of clean engine oil to o-ring.
(6) Note fuel inlet hole on side of fuel injector. This
hole must be positioned towards injector connector
tube. Position injector into cylinder head bore being
extremely careful not to allow injector tip to touch
sides of bore. Press fuel injector into cylinder head
with finger pressure only.Do not use any tools to
press fuel injector into position. Damage to
machined surfaces may result.
(7) Position fuel injector hold down clamp into
shouldered bolt while aligning slot in top of injector
into groove in bottom of clamp. Tighten opposite
clamp bolt (Fig. 18) to 10 N´m (89 in. lbs.) torque.
(8) Install new o-ring to fuel injector connector
tube. Apply small amount of clean engine oil to
o-ring.(9) Press injector connector tube into cylinder head
with finger pressure only.Do not use any tools to
press tube into position. Damage to machined
surfaces may result.
(10) Connect high-pressure fuel lines. Refer to
High-Pressure Fuel Lines Removal/Installation.The
fuel line fitting torque is very critical.If fitting
is under torqued, the mating surfaces will not seal
and a high-pressure fuel leak will result. If fitting is
over torqued, the connector and injector will deform
and also cause a high-pressure fuel leak. This leak
will be inside cylinder head and will not be visible
resulting in a possible fuel injector miss and low
power.
(11) Install valve cover. (Refer to 9 - ENGINE/
CYLINDER HEAD/CYLINDER HEAD COVER(S) -
INSTALLATION).
(12) (If necessary) install intake manifold air
heater assembly. Refer to Intake Manifold Air Heater
Removal/Installation.
(13) (If necessary) install engine lifting bracket.
Tighten 2 bolts to 77 N´m (57 ft. lbs.) torque.
(14) Connect negative battery cables to both bat-
teries.
(15) Bleed air from high-pressure lines (Refer to 14
- FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE).
FUEL INJECTION PUMP
RELAY
DESCRIPTION
The fuel injection pump relay is located in the
Power Distribution Center (PDC). Refer to label
under PDC cover for relay location.
OPERATION
The Engine Control Module (ECM) energizes the
electric fuel injection pump through the fuel injection
pump relay. Battery voltage is applied to the fuel
injection pump relay at all times. When the key is
turned ON, the relay is energized when a 12±volt sig-
nal is provided by the ECM. When energized,
12±volts is supplied to the Fuel Pump Control Mod-
ule. The Fuel Pump Control Module is located on the
top of the fuel injection pump and is non-servicable.
Fig. 24 Cleaning Cylinder Head Injector BoreÐ
TYPICAL BORE
1 - INJECTOR BORE
2 - WIRE BRUSH
BR/BEFUEL INJECTION - DIESEL 14 - 103
FUEL INJECTOR (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0157 (M) 2/2 O2 Sensor Shorted To Ground Oxygen sensor input voltage maintained below normal
operating range.
P0158 (M) 2/2 O2 Sensor Shorted To Voltage Oxygen sensor input voltage maintained above normal
operating range.
P0159 2/2 O2 Sensor Slow Response Oxygen sensor response slower than minimum required
switching frequency.
P0160 (M) 2/2 O2 Sensor Stays at Center Neither rich or lean condition is detected from the oxygen
sensor.
P0161 (M) 2/2 O2 Sensor Heater Failure Oxygen sensor heater element malfunction.
PO165 Starter Relay Circuit Problem detected in starter relay circuit.
P0168 Decreased Engine Performance Due
To High Injection Pump Fuel TempFuel temperature is above the engine protection limit. Engine
power will be derated.
P0171 (M) 1/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0172 (M) 1/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0174 (M) 2/1 Fuel System Lean A lean air/fuel mixture has been indicated by an abnormally
rich correction factor.
P0175 (M) 2/1 Fuel System Rich A rich air/fuel mixture has been indicated by an abnormally
lean correction factor.
P0176 Loss of Flex Fuel Calibration Signal No calibration voltage present from flex fuel sensor.
P0177 Water In Fuel Excess water found in fuel by water-in-fuel sensor.
P0178 Flex Fuel Sensor Volts Too Low Flex fuel sensor input below minimum acceptable voltage.
P0178 Water In Fuel Sensor Voltage Too Low Loss of water-in-fuel circuit or sensor.
P0179 Flex Fuel Sensor Volts Too High Flex fuel sensor input above maximum acceptable voltage.
P0181 Fuel Injection Pump Failure Low power, engine derated, or engine stops.
P0182 (M) CNG Temp Sensor Voltage Too Low Compressed natural gas temperature sensor voltage below
acceptable voltage.
P0183 (M) CNG Temp Sensor Voltage Too High Compressed natural gas temperature sensor voltage above
acceptable voltage.
P0201 (M) Injector #1 Control Circuit An open or shorted condition detected in control circuit for
injector #1 or the INJ 1 injector bank.
P0202 (M) Injector #2 Control Circuit An open or shorted condition detected in control circuit for
injector #2 or the INJ 2 injector bank.
P0203 (M) Injector #3 Control Circuit An open or shorted condition detected in control circuit for
injector #3 or the INJ 3 injector bank.
P0204 (M) Injector #4 Control Circuit Injector #4 or INJ 4 injector bank output driver stage does
not respond properly to the control signal.
P0205 (M) Injector #5 Control Circuit Injector #5 output driver stage does not respond properly to
the control signal.
P0206 (M) Injector #6 Control Circuit Injector #6 output driver stage does not respond properly to
the control signal.
BR/BEEMISSIONS CONTROL 25 - 5
EMISSIONS CONTROL (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0207 (M) Injector #7 Control Circuit Injector #7 output driver stage does not respond properly to
the control signal.
P0208 (M) Injector #8 Control Circuit Injector #8 output driver stage does not respond properly to
the control signal.
P0209 (M) Injector #9 Control Circuit Injector #9 output driver stage does not respond properly to
the control signal.
P0210 (M) Injector #10 Control Circuit Injector #10 output driver stage does not respond properly to
the control signal.
P0215 Fuel Injection Pump Control Circuit Failure in fuel pump relay control circuit.
P0216 (M) Fuel Injection Pump Timing Failure High fuel supply restriction, low fuel pressure or possible
wrong or incorrectly installed pump keyway.
P0217 Decreased Engine Performance Due
To Engine Overheat ConditionEngine overheating. ECM will derate engine performance.
P0219 Crankshaft Position Sensor Overspeed
SignalEngine has exceeded rpm limits.
P0222 (M) Idle Validation Signals Both Low Problem detected with idle validation circuits within APPS.
P0223 (M) Idle Validation Signals Both High
(Above 5 Volts)Problem detected with idle validation circuits within APPS.
P0230 Transfer Pump (Lift Pump) Circuit Out
of RangeProblem detected in fuel transfer pump circuits.
P0232 Fuel Shutoff Signal Voltage Too High Fuel shut-off signal voltage too high from ECM to fuel
injection pump.
P0234 (M) Turbo Boost Limit Exceeded Problem detected in turbocharger wastegate.
P0236 (M) Map Sensor Too High Too Long Problem detected in turbocharger wastegate.
P0237 (M) Map Sensor Voltage Too Low MAP sensor voltage input below the minimum acceptable
voltage.
P0238 (M) Map Sensor Voltage Too High MAP sensor voltage input above the maximum acceptable
voltage.
PO243 Wastegate Solenoid Circuit
P0251 (M) Fuel Inj. Pump Mech. Failure Fuel
Valve Feedback CircuitProblem sensed with fuel circuit internal to fuel injection
pump.
P0253 (M) Fuel Injection Pump Fuel Valve Open
CircuitProblem sensed with fuel circuit internal to fuel injection
pump.
P0254 Fuel Injection Pump Fuel Valve
Current Too HighProblem caused by internal fuel injection pump failure.
P0300 (M) Multiple Cylinder Mis-fire Misfire detected in multiple cylinders.
P0301 (M) CYLINDER #1 MISFIRE Misfire detected in cylinder #1.
P0302 (M) CYLINDER #2 MISFIRE Misfire detected in cylinder #2.
P0303 (M) CYLINDER #3 MISFIRE Misfire detected in cylinder #3.
P0304 (M) CYLINDER #4 MISFIRE Misfire detected in cylinder #4.
P0305 (M) CYLINDER #5 MISFIRE Misfire detected in cylinder #5.
P0306 (M) CYLINDER #6 MISFIRE Misfire detected in cylinder #6.
25 - 6 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)

DESCRIPTION - TASK MANAGER
The PCM is responsible for efficiently coordinating
the operation of all the emissions-related compo-
nents. The PCM is also responsible for determining if
the diagnostic systems are operating properly. The
software designed to carry out these responsibilities
is call the 'Task Manager'.
DESCRIPTION - MONITORED SYSTEMS
There are new electronic circuit monitors that
check fuel, emission, engine and ignition perfor-
mance. These monitors use information from various
sensor circuits to indicate the overall operation of the
fuel, engine, ignition and emission systems and thus
the emissions performance of the vehicle.
The fuel, engine, ignition and emission systems
monitors do not indicate a specific component prob-
lem. They do indicate that there is an implied prob-
lem within one of the systems and that a specific
problem must be diagnosed.
If any of these monitors detect a problem affecting
vehicle emissions, the Malfunction Indicator Lamp
(MIL) will be illuminated. These monitors generate
Diagnostic Trouble Codes that can be displayed with
the MIL or a scan tool.
The following is a list of the system monitors:
²Misfire Monitor
²Fuel System Monitor
²Oxygen Sensor Monitor
²Oxygen Sensor Heater Monitor
²Catalyst Monitor
²Leak Detection Pump Monitor (if equipped)
All these system monitors require two consecutive
trips with the malfunction present to set a fault.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
The following is an operation and description of
each system monitor :
OXYGEN SENSOR (O2S) MONITOR
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The O2S is also the main sensing element for the
Catalyst and Fuel Monitors.The O2S can fail in any or all of the following
manners:
²slow response rate
²reduced output voltage
²dynamic shift
²shorted or open circuits
Response rate is the time required for the sensor to
switch from lean to rich once it is exposed to a richer
than optimum A/F mixture or vice versa. As the sen-
sor starts malfunctioning, it could take longer to
detect the changes in the oxygen content of the
exhaust gas.
The output voltage of the O2S ranges from 0 to 1
volt. A good sensor can easily generate any output
voltage in this range as it is exposed to different con-
centrations of oxygen. To detect a shift in the A/F
mixture (lean or rich), the output voltage has to
change beyond a threshold value. A malfunctioning
sensor could have difficulty changing beyond the
threshold value.
OXYGEN SENSOR HEATER MONITOR
If there is an oxygen sensor (O2S) shorted to voltage
DTC, as well as a O2S heater DTC, the O2S fault
MUST be repaired first. Before checking the O2S fault,
verify that the heater circuit is operating correctly.
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572 É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The voltage readings taken from the O2S sensor
are very temperature sensitive. The readings are not
accurate below 300ÉC. Heating of the O2S sensor is
done to allow the engine controller to shift to closed
loop control as soon as possible. The heating element
used to heat the O2S sensor must be tested to ensure
that it is heating the sensor properly.
The O2S sensor circuit is monitored for a drop in
voltage. The sensor output is used to test the heater
by isolating the effect of the heater element on the
O2S sensor output voltage from the other effects.
LEAK DETECTION PUMP MONITOR (IF EQUIPPED)
The leak detection assembly incorporates two pri-
mary functions: it must detect a leak in the evapora-
tive system and seal the evaporative system so the
leak detection test can be run.
BR/BEEMISSIONS CONTROL 25 - 17
EMISSIONS CONTROL (Continued)

The primary components within the assembly are:
A three port solenoid that activates both of the func-
tions listed above; a pump which contains a switch,
two check valves and a spring/diaphragm, a canister
vent valve (CVV) seal which contains a spring loaded
vent seal valve.
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, indicated
by 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.
25 - 18 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)

²Absolute MAP When Misfire OccurredÐ
The stored MAP reading at the time of failure.
Informs the user at what engine load the failure
occurred.
²Absolute MAPÐ A live reading of engine load
to aid the user in accessing the Similar Conditions
Window.
²RPM When Misfire OccurredÐ The stored
RPM reading at the time of failure. Informs the user
at what engine RPM the failure occurred.
²Engine RPMÐ A live reading of engine RPM
to aid the user in accessing the Similar Conditions
Window.
²Adaptive Memory FactorÐ The PCM utilizes
both Short Term Compensation and Long Term Adap-
tive to calculate the Adaptive Memory Factor for
total fuel correction.
²200 Rev CounterÐ Counts 0±100 720 degree
cycles.
²SCW Cat 200 Rev CounterÐ Counts when in
similar conditions.
²SCW FTP 1000 Rev CounterÐ Counts 0±4
when in similar conditions.
²Misfire Good Trip CounterÐ Counts up to
three to turn OFF the MIL.
²Misfire DataÐ Data collected during test.
²Test Done This TripÐ Indicates YES when the
test is done.
OPERATION - NON-MONITORED CIRCUITS -
GAS ENGINES
The PCM does not monitor the following circuits,
systems and conditions that could have malfunctions
causing driveability problems. The PCM might not
store diagnostic trouble codes for these conditions.
However, problems with these systems may cause the
PCM to store diagnostic trouble codes for other sys-
tems or components.EXAMPLE:a fuel pressure
problem will not register a fault directly, but could
cause a rich/lean condition or misfire. This could
cause the PCM to store an oxygen sensor or misfire
diagnostic trouble code
FUEL PRESSURE
The fuel pressure regulator controls fuel system
pressure. The PCM cannot detect a clogged fuel
pump inlet filter, clogged in-line fuel filter, or a
pinched fuel supply or return line. However, these
could result in a rich or lean condition causing the
PCM to store an oxygen sensor or fuel system diag-
nostic trouble code.
SECONDARY IGNITION CIRCUIT
The PCM cannot detect an inoperative ignition coil,
fouled or worn spark plugs, ignition cross firing, or
open spark plug cables.CYLINDER COMPRESSION
The PCM cannot detect uneven, low, or high engine
cylinder compression.
EXHAUST SYSTEM
The PCM cannot detect a plugged, restricted or
leaking exhaust system, although it may set a fuel
system fault.
FUEL INJECTOR MECHANICAL MALFUNCTIONS
The PCM cannot determine if a fuel injector is
clogged, the needle is sticking or if the wrong injector
is installed. However, these could result in a rich or
lean condition causing the PCM to store a diagnostic
trouble code for either misfire, an oxygen sensor, or
the fuel system.
EXCESSIVE OIL CONSUMPTION
Although the PCM monitors engine exhaust oxygen
content when the system is in closed loop, it cannot
determine excessive oil consumption.
THROTTLE BODY AIR FLOW
The PCM cannot detect a clogged or restricted air
cleaner inlet or filter element.
VACUUM ASSIST
The PCM cannot detect leaks or restrictions in the
vacuum circuits of vacuum assisted engine control
system devices. However, these could cause the PCM
to store a MAP sensor diagnostic trouble code and
cause a high idle condition.
PCM SYSTEM GROUND
The PCM cannot determine a poor system ground.
However, one or more diagnostic trouble codes may
be generated as a result of this condition. The mod-
ule should be mounted to the body at all times, also
during diagnostic.
PCM CONNECTOR ENGAGEMENT
The PCM may not be able to determine spread or
damaged connector pins. However, it might store
diagnostic trouble codes as a result of spread connec-
tor pins.
OPERATION - NON-MONITORED CIRCUITS -
DIESEL
The PCM and/or the ECM will not monitor certain
malfunctioning circuits or components that could
cause driveability problems. Also, a Diagnostic Trou-
ble Code (DTC) might not be stored for these mal-
functions. However, problems with these circuits or
components may cause the PCM/ECM to store DTC's
for other circuits or components.EXAMPLES:A cyl-
inder with low compression will not set a DTC
25 - 24 EMISSIONS CONTROLBR/BE
EMISSIONS CONTROL (Continued)