2001 DODGE RAM Valve

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. A meltdown of the ceramic core can
cause a reduction of the exhaust passage. 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
O2S is used to detect the amount of oxygen in the
exhaust gas before the gas enters the catalytic con-
verter. The PCM calculates the A/F mixture from the
output of the O2S. A low voltage indicates high oxy-
gen content (lean mixture). A high voltage indicates a
low content of oxygen (rich mixture).
When the upstream O2S detects a lean condition,
there is an abundance of oxygen in the exhaust gas.
A functioning converter would store this oxygen so it
can use it for the oxidation of HC and CO. As the
converter absorbs the oxygen, there will be a lack of
oxygen downstream of the converter. The output of
the downstream O2S will indicate limited activity in
this condition.
As the converter loses the ability to store oxygen,
the condition can be detected from the behavior of
the downstream O2S. When the efficiency drops, no
chemical reaction takes place. This means the con-
centration of oxygen will be the same downstream as
upstream. The output voltage of the downstream
O2S copies the voltage of the upstream sensor. The
only difference is a time lag (seen by the PCM)
between the switching of the O2S's.
To monitor the system, the number of lean-to-rich
switches of upstream and downstream O2S's is
counted. The ratio of downstream switches to
upstream switches is used to determine whether the
catalyst is operating properly. An effective catalyst
will have fewer downstream switches than it has
upstream switches i.e., a ratio closer to zero. For a
totally ineffective catalyst, this ratio will be one-to-
one, indicating that no oxidation occurs in the device.
The system must be monitored so that when cata-
lyst efficiency deteriorates and exhaust emissions
increase to over the legal limit, the MIL will be illu-
minated.
BR/BEEMISSIONS CONTROL 25 - 17
EMISSIONS CONTROL (Continued)

AIR INJECTION
TABLE OF CONTENTS
page page
AIR INJECTION
DESCRIPTION...........................25
OPERATION.............................27
SPECIFICATIONS........................28
AIR INJECTION PUMP
DESCRIPTION...........................28
OPERATION.............................28
DIAGNOSIS AND TESTING.................28
AIR INJECTION PUMP...................28
REMOVAL..............................29
INSTALLATION...........................29AIR PUMP FILTER
REMOVAL..............................29
INSTALLATION...........................29
ONE WAY CHECK VALVE
DESCRIPTION...........................30
OPERATION.............................30
DIAGNOSIS AND TESTING.................30
TESTING ONE-WAY CHECK VALVE.........30
REMOVAL..............................30
INSTALLATION...........................30
AIR INJECTION
DESCRIPTION - AIR INJECTION SYSTEM
The air injection system (Fig. 1), (Fig. 2) or (Fig. 3)
is used on 5.9L V-8 and 8.0L V-10 heavy duty cycle
(HDC) gas powered engines only. The air injection
system consists of:²A belt-driven air injection (AIR) pump
²Two air pressure relief valves
²Rubber connecting air injection hoses with
clamps
²Metal connecting air tubes
²Two one-way check valves
²A replaceable injection pump air filter (8.0L V-10
engine only)
BR/BEAIR INJECTION 25 - 25

Fig. 1 Air Injection System ComponentsÐTypical
1 - CATALYTIC CONVERTORS (2)
2 - ONE-WAY CHECK VALVES (2)
3-88Y'' CONNECTOR
4 - PRESSURE RELIEF VALVE
5 - HOSE
6 - CLAMPS
7 - HOSE
8 - CLAMP9 - AIR INJECTION PUMP
10 - INLET AIR FITTING
11 - OUTLET AIR FITTING
12 - METAL CONNECTING TUBE
13 - HOSE
14 - CLAMPS
25 - 26 AIR INJECTIONBR/BE
AIR INJECTION (Continued)

OPERATION - AIR INJECTION SYSTEM
The air injection system adds a controlled amount
of air to the exhaust gases aiding oxidation of hydro-
carbons and carbon monoxide in the exhaust stream.
The system does not interfere with the ability of the
EGR system (if used) to control nitrous oxide (NOx)
emissions.
5.9L HDC ENGINE:Air is drawn into the pump
through a rubber tube that is connected to a fitting
on the air cleaner housing (Fig. 2).
8.0L V-10 ENGINE:Air is drawn into the pump
through a rubber tube that is connected to a fitting
on the air injection pump filter housing (Fig. 3). Air
is drawn into the filter housing from the front of the
vehicle with rubber tube. This tube is used as asilencer to help prevent air intake noise at the open-
ing to the pump filter housing. An air filter is located
within the air pump filter housing (Fig. 3).
Air is then compressed by the air injector pump. It
is expelled from the pump and routed into a rubber
tube where it reaches the air pressure relief valve
(Fig. 1). Pressure relief holes in the relief valve will
prevent excess downstream pressure. If excess down-
stream pressure occurs at the relief valve, it will be
vented into the atmosphere.
Air is then routed (Fig. 1) from the relief valve,
through a tube, down to a9Y9connector, through the
two one-way check valves and injected at both of the
catalytic convertors (referred to as downstream).
The two one-way check valves (Fig. 1) protect the
hoses, air pump and injection tubes from hot exhaust
gases backing up into the system. Air is allowed to
flow through these valves in one direction only
(towards the catalytic convertors).
Downstream air flow assists the oxidation process
in the catalyst, but does not interfere with EGR oper-
ation (if EGR system is used).
Fig. 2 Air Inlet for Air PumpÐ5.9L HDC Engine
1 - AIR FILTER HOUSING
2 - AIR INLET TUBE
3 - INLET AIR FITTING
4 - AIR INJECTION PUMP
5 - OUTLET AIR FITTING
Fig. 3 Air Inlet and Air Pump Air
1 - INJECTION PUMP AIR FILTER HOUSING
2 - R. F. INNER FENDER
3 - FILTER HOUSING MOUNTING NUT
4 - PRESSURE RELIEF VALVE
5 - HOSE CLAMPS
6 - AIR INJECTION PUMP
7 - AIR INLET REDUCER
8 - LID
BR/BEAIR INJECTION 25 - 27
AIR INJECTION (Continued)

SPECIFICATIONS
TORQUE - AIR INJECTION SYSTEM
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Air Pump Filter Housing
Nut18
Air Pump Mounting Bolts 40 30
Air Pump Pulley Mounting
Bolts11 105
One-Way Check Valve to
Catalyst Tube33 25
AIR INJECTION PUMP
DESCRIPTION
The air pump is mounted on the front of the
engine and driven by a belt connected to the crank-
shaft pulley (Fig. 4).
OPERATION
Refer to Air Injection System Description and
Operation for information.
DIAGNOSIS AND TESTING - AIR INJECTION
PUMP
The air injection system and air injection
pump is not completely noiseless.Under normal
conditions, noise rises in pitch as engine speed
increases. To determine if excessive noise is fault of
air injection system, disconnect accessory drive belt
and temporarily operate engine.Do not allow
engine to overheat when operating without
drive belt.
CAUTION: Do not attempt to lubricate the air injec-
tion pump. Oil in the pump will cause rapid deteri-
oration and failure.
Fig. 4 Air Injection Pump MountingÐTypical
1 - PUMP PULLEY
2 - AIR PUMP
3 - AUTOMATIC BELT TENSIONER
4 - PUMP MOUNTING BOLTS (2)
5 - PULLEY BOLTS
25 - 28 AIR INJECTIONBR/BE
AIR INJECTION (Continued)

EXCESSIVE BELT NOISE1. Loose belt or defective automatic
belt tensioner.1. Refer to Cooling System.
2. Seized pump. 2. Replace pump.
EXCESSIVE PUMP NOISE
CHIRPING1. Insufficient break-in. 1. Recheck for noise after 1600 km
(1,000 miles) of operation.
EXCESSIVE PUMP NOISE
CHIRPING, RUMBLING, OR
KNOCKING1. Leak in hose. 1. Locate source of leak using soap
solution and correct.
2. Loose hose. 2. Reassemble and replace or tighten
hose clamp.
3. Hose touching other engine parts. 3. Adjust hose position.
4. Relief valve inoperative. 4. Replace relief valve.
5. Check valve inoperative. 5. Replace check valve.
6. Pump mounting fasteners loose. 6. Tighten mounting screws as
specified.
7. Pump failure. 7. Replace pump.
NO AIR SUPPLY.
ACCELERATE ENGINE TO
1500 RPM AND OBSERVE
AIR FLOW FROM HOSES. IF
FLOW INCREASES AS
RPM'S INCREASE, PUMP IS
FUNCTIONING NORMALLY.
IF NOT, CHECK POSSIBLE
CAUSE.1. Loose drive belt. 1. Refer to Cooling System.
2. Leaks in supply hose. 2. Locate leak and repair or replace as
required.
3. Leak at fitting(s). 3. Tighten and replace clamps.
4. Check valve inoperative. 4. Replace check valve.
5. Plugged inlet air filter (8.0L). 5. Replace filter
REMOVAL
The air injection pump does not have any internal
serviceable parts.
(1) Disconnect both of the hoses (tubes) at the air
injection pump.
(2) Loosen, but do not remove at this time, the
three air pump pulley mounting bolts (Fig. 4).
(3) Relax the automatic belt tensioner and remove
the engine accessory drive belt. Refer to Cooling Sys-
tem. See Belt Removal/Installation.
(4) Remove the three air pump pulley bolts and
remove pulley from pump.
(5) Remove the two air pump mounting bolts (Fig.
4) and remove pump from mounting bracket.
INSTALLATION
(1) Position air injection pump to mounting
bracket.
(2) Install two pump mounting bolts to mounting
bracket. Tighten bolts to 40 N´m (30 ft. lbs.) torque.
(3) Install pump pulley and three mounting bolts.
Tighten bolts finger tight.
(4) Relax tension from automatic belt tensioner
and install drive belt. Refer to Cooling System. See
Belt Removal/Installation.(5) Tighten pump pulley bolts to 11 N´m (105 in.
lbs.) torque.
(6) Install hoses and hose clamps at pump.
AIR PUMP FILTER
REMOVAL
The air filter for the air injection pump is located
inside a housing located in right-front side of engine
compartment (Fig. 3). A rubber hose connects the fil-
ter housing to air injection pump. The filter is used
with 8.0L V-10 engines only.
(1) Remove rubber tubes at filter housing.
(2) Remove filter housing mounting nut and
remove housing.
(3) Remove lid from filter housing (snaps off).
(4) Remove filter from housing.
INSTALLATION
The air filter for the air injection pump is located
inside a housing located in right-front side of engine
compartment (Fig. 3). A rubber hose connects the fil-
ter housing to air injection pump. The filter is used
with 8.0L V-10 engines only.
BR/BEAIR INJECTION 25 - 29
AIR INJECTION PUMP (Continued)

(1) Clean inside of housing and lid before install-
ing new filter.
(2) Install filter into housing.
(3) Install lid to filter housing (snaps on).
(4) Position filter housing to fender.
(5) Install mounting nut and tighten to 11 N´m (8
ft. lbs.) torque.
(6) Install rubber tubes and cap at filter housing.
ONE WAY CHECK VALVE
DESCRIPTION
For air injection systems:A pair of one-way
check valves is used with the air injection system.
The check valves (Fig. 1) are located on each of the
air injection downstream tubes.
OPERATION
Each one-way check valve has a one-way dia-
phragm which prevents hot exhaust gases from back-
ing up into the air injection hose and air injection
pump. The check valve will protect the system if the
air injection pump belt fails, an air hose ruptures or
exhaust system pressure becomes abnormally high.
DIAGNOSIS AND TESTING - ONE-WAY CHECK
VALVE
The one-way check valves are not repairable. To
determine condition of valve, remove the rubber air
tube from the inlet side of each check valve. Start the
engine. If exhaust gas is escaping through the inlet
side of check valve, it must be replaced.
REMOVAL
(1) Remove the hose clamp at inlet side of valve.
(2) Remove hose from valve.
(3) Remove valve from catalyst tube (unscrew).To
prevent damage to catalyst tube, a backup
wrench must be used on the tube.
INSTALLATION
(1) Install valve to catalyst tube. Tighten to 33
N´m (25 ft. lbs.) torque.
(2) Install hose and hose clamp to valve.
25 - 30 AIR INJECTIONBR/BE
AIR PUMP FILTER (Continued)

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION...........................31
SPECIFICATIONS........................31
CCV HOSE
DESCRIPTION...........................32
OPERATION.............................32
CRANKCASE VENT HOSE
DESCRIPTION...........................32
EVAP/PURGE SOLENOID
DESCRIPTION...........................32
REMOVAL..............................32
INSTALLATION...........................32
FUEL FILLER CAP
DESCRIPTION...........................33
OPERATION.............................33
REMOVAL..............................33
LEAK DETECTION PUMP
DESCRIPTION...........................33REMOVAL..............................34
INSTALLATION...........................34
PCV FILTER
DESCRIPTION...........................35
P C V VA LV E
DESCRIPTION...........................35
OPERATION.............................35
DIAGNOSIS AND TESTING.................36
PCV VALVE TEST - 3.9/5.2/5.9L ENGINE.....36
VACUUM LINES
DIAGNOSIS AND TESTING.................37
VACUUM SCHEMATICS..................37
VAPOR CANISTER
DESCRIPTION...........................37
OPERATION.............................37
REMOVAL..............................37
INSTALLATION...........................38
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAP SYSTEM
The evaporation control system prevents the emis-
sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through vent hoses or tubes into the two charcoal
filled evaporative canisters. The canisters tempo-
rarily hold the vapors. The Powertrain Control Mod-
ule (PCM) allows intake manifold vacuum to draw
vapors into the combustion chambers during certain
operating conditions.
All 3.9L/5.2L/5.9L/8.0L gasoline powered engines
use a duty cycle purge system. The PCM controlsvapor flow by operating the duty cycle EVAP purge
solenoid. Refer to Duty Cycle EVAP Canister Purge
Solenoid for additional information.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system. This pump is used as part of
OBD II requirements. Refer to Leak Detection Pump
in this group for additional information.
NOTE: The hoses used in this system are specially
manufactured. If replacement becomes necessary, it
is important to use only fuel resistant hose.
SPECIFICATIONS
TORQUE - EVAP SYSTEM
DESCRIPTION N´m Ft. Lbs. In. Lbs.
EVAP Canister Mounting Nuts 9 80
Leak Detection Pump Mounting Screws 1 11
Leak Detection Pump Filter Mounting
Bolt765
BR/BEEVAPORATIVE EMISSIONS 25 - 31