Dodge Viper SRT-10 (ZB). Manual — part 183
Valves use a butterfly style valve to restrict exhaust
from exiting the side of the vehicle. The diverted
exhaust is then carried to the Auxiliary Resonator
where it is exhausted to the atmosphere (Fig. 1).
The majority of driving conditions will find the
Exhaust Diverter Valves deactivated. During the
deactivation
mode,
the
butterfly
valves
in
the
Diverter
Valves
are
open.
During
deactivation,
exhaust flow is directed primarily through the side
exhaust pipes. But, there is also a parallel path for
exhaust to flow out to the Auxiliary Resonator. The
deactivation position is also the default position of
the valves, thereby allowing full exhaust flow in the
event of a system failure (Fig. 2).
DIAGNOSIS AND TESTING - EXHAUST SYSTEM
RESTRICTION CHECK
Exhaust system restriction can be checked by mea-
suring back pressure using the DRB III
t and PEP
module pressure tester.
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
(1) Disconnect and remove the upstream (before
catalytic converter) oxygen sensor (Refer to 14 -
FUEL SYSTEM/FUEL INJECTION/O2 SENSOR -
REMOVAL).
(2) Install the Exhaust Back Pressure Fitting
Adaptor CH8519.
(3) Connect the Low Pressure Sensor (15 psi)
CH7063 to the back pressure fitting.
(4) Following the PEP module instruction manual,
connect all required cables to the DRB III
t and PEP
module. Select the available menu options on the
DRBIII
t display screen for using the digital pressure
gauge function.
(5) Apply the park brake and start the engine.
(6) With transmission in Neutral, raise engine
speed to 2000 RPM. Monitor the pressure readings
on the DRBIII
t. Back pressure should not exceed
specified limit. Refer to specification in table below
EXHAUST BACK PRESSURE LIMITS.
NOTE: Repeat test on opposite converter using the
previous steps.
Fig. 1 VACUUM DIAGRAM
(
DEACTIVATED
(
11 - 2
EXHAUST SYSTEM
ZB
EXHAUST SYSTEM (Continued)
(7) If pressure exceeds maximum limits, inspect
exhaust system for restricted component. For further
catalytic converter inspection procedures, (Refer to 11
- EXHAUST SYSTEM/CATALYTIC CONVERTER -
INSPECTION). Replace component(s) as necessary.
EXHAUST BACK PRESSURE LIMITS
Exhaust Back Pressure Limit (Max)
Vehicle in Park/Neutral
(no load) @2000 RPM
3.45 Kpa (0.5 psi)
INSPECTION
EXHAUST SYSTEM INSPECTION
Inspect the exhaust pipes, catalytic converters, and
resonators for cracked joints, broken welds and cor-
rosion damage that would result in a leaking exhaust
system. Inspect the clamps, support brackets, and
isolators for cracks and corrosion damage.
NOTE: Slip joint band clamps are spot welded to
exhaust system. If a band clamp must be replaced,
the spot weld must be ground off.
ADJUSTMENTS
EXHAUST SYSTEM ALIGNMENT
A misaligned exhaust system is usually indicated
by a vibration, rattling noise, or binding of exhaust
system components. These noises are sometimes hard
to distinguish from other chassis noises. Inspect
exhaust system for broken or loose clamps, heat
shields, isolators, and brackets. Replace or tighten as
necessary. It is important that exhaust system clear-
ances and alignment be maintained.
Perform the following procedures to align the
exhaust system:
(1) Loosen clamps and support brackets.
(2) Align the exhaust system starting at the front,
working rearward.
(3) Tighten all clamps and brackets once align-
ment and clearances are achieved.
Fig. 2 VACUUM DIAGRAM
(
ACTIVATED
(
ZB
EXHAUST SYSTEM
11 - 3
EXHAUST SYSTEM (Continued)
SPECIFICATIONS
TORQUE
DESCRIPTION
N·m
Ft.
Lbs.
In.
Lbs.
Band Clamp—Nut
54
40
—
Catalytic Converter V-Band
Clamp—Nut
11
—
100
Support Isolators (
9
A
9
and
9
B
9
Pil-
lar)—Bolts
28
—
250
SPECIAL TOOLS
EXHAUST SYSTEM
PIPE CLAMPS
DESCRIPTION
A V-band clamp (Fig. 3) secures the catalytic con-
verter to exhaust manifold connection. When the
V-band clamp is tightened, it forces the flared mating
surfaces of the manifold and the catalytic converter
pipe together. This seals and supports the joint.
NOTE: The V-band clamp must be replaced when
removed.
Band clamps are also used to secure exhaust pipe
connections (Fig. 4).
NOTE: Band clamps are spot welded to exhaust
system. If a band clamp must be replaced, the spot
weld must be ground off.
Back Pressure Test Adapter - CH8519
Pressure Transducer - CH7063
DRB III & PEP Module - OT-CH6010A
Fig. 3 V-Band Clamp
1 - T—BOLT
Fig. 4 Band Clamp
1 - BAND CLAMP
2 - TORQUE SPECIFICATION
11 - 4
EXHAUST SYSTEM
ZB
EXHAUST SYSTEM (Continued)
HEAT SHIELDS
DESCRIPTION
High temperatures can develop around the cata-
lytic converters and resonators. Because of this, heat
shields (Fig. 5) and (Fig. 6) are necessary to protect
both the car and the environment.
CATALYTIC CONVERTER(S)
OPERATION
The three-way catalytic converter simultaneously
converts three exhaust emissions into harmless
gases. Specifically, HC and CO emissions are con-
verted into water (H2O) and carbon dioxide (CO2).
Oxides of Nitrogen (NOx) are converted into elemen-
tal Nitrogen (N) and water. The three-way catalyst is
most efficient in converting HC, CO and NOx at the
stoichiometric air fuel ratio of 14.7:1.
The oxygen content in a catalyst is important for
efficient conversion of exhaust gases. When a high
oxygen content (lean) air/fuel ratio is present for an
extended period, oxygen content in a catalyst can
reach a maximum. When a rich air/fuel ratio is
present for an extended period, the oxygen content in
the catalyst can become totally depleted. When this
occurs, the catalyst fails to convert the gases. This is
known as catalyst
9punch through.9
Proper catalyst operation is dependent on its abil-
ity to store and release the oxygen needed to com-
plete the emissions-reducing chemical reactions. As a
catalyst deteriorates, its ability to store oxygen is
reduced. Since the catalyst’s ability to store oxygen is
somewhat related to proper operation, oxygen storage
can be an indicator of catalyst performance. Refer to
the appropriate powertrain diagnostic procedure for
diagnosis of a catalyst-related Diagnostic Trouble
Code (DTC).
The combustion reaction caused by the catalyst
releases additional heat in the exhaust system.
Under severe operating conditions, this causes tem-
perature increases in the area of the reactor. Severe
operating conditions can exist when the engine mis-
fires or otherwise does not operate at peak efficiency.
NOTE: If the exhaust system is equipped with a cat-
alytic converter, do not remove spark plug wires
from plugs, or short out cylinders by any other
means.
The catalytic converter can fail because of temper-
ature increases caused by unburned fuel passing
through the converter. This deterioration of the cata-
lyst core can result in excessively high emission lev-
els, noise complaints, and exhaust restrictions.
Unleaded gasoline must be used to avoid poisoning
the catalyst core. Do not operate the engine in neu-
tral above 1200 RPM for extended periods over 5
minutes. Because there is no air movement under
the vehicle, excessive exhaust system/floor pan tem-
peratures may result.
CAUTION: Due to exterior physical similarities of
some catalytic converters with pipe assemblies,
extreme care should be taken with replacement
parts. Internal converter differences are required in
some parts of the country (particularly vehicles
built for states with strict emission requirements).
REMOVAL
NOTE: This procedure covers removal of either the
right OR left catalytic converter. Remove the appro-
priate parts for the side that is being worked on.
(1) Raise vehicle on hoist (Refer to LUBRICATION
& MAINTENANCE/HOISTING - STANDARD PRO-
CEDURE).
(2) Remove sill panel (Refer to 23 - BODY/EXTE-
RIOR/SILL PANEL - REMOVAL) (Fig. 7).
Fig. 5 Catalytic Converter Heat Shield (Right Side
Shown - Left Side Typical)
1 - RIGHT INNER FRAME RAIL
2 - STUD
3 - HEAT SHIELD
4 - NUT
ZB
EXHAUST SYSTEM
11 - 5
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