Page 1265 of 1938

CAUTION: When servicing, care must be exercised
not to dent or bend the bellows of the flex-joint.
Should this occur, the flex-joint will eventually fail
and require the catalytic converter be replaced.
DESCRIPTION AND OPERATION
INTAKE/EXHAUST MANIFOLDÐ2.4L ENGINE
The intake manifold is a tuned two-piece alumi-
num casting with individual primary runners leading
from a plenum to the cylinders. The manifold is
designed to boost torque which is desired for excel-
lent engine response and usable power output.
The exhaust manifold is made of nodular cast iron
for strength and high temperatures.
INTAKE/EXHAUST MANIFOLDÐ3.0L ENGINE
The aluminum alloy manifold is a cross type with
long runners to improve air flow. The runners,
attaching below at the cylinder head, also attach
above and support an air plenum. The air plenum
chamber absorbs air pulsations created during the
suction phase of each cylinder.Both exhaust manifolds are a log style made of
ductile cast iron. Exhaust gasses, collected from the
front cylinder bank, leave the front manifold through
an end outlet and are fed through an upper crossover
tube to the rear manifold. The collected exhaust from
both manifolds are combined at the exhaust outlet, to
the exhaust pipe.
INTAKE/EXHAUST MANIFOLDÐ3.3/3.8L ENGINES
The intake manifold is a tuned two-piece semi-per-
manent mold aluminum casting with individual pri-
mary runners leading from a plenum to the
cylinders. The manifold is designed to boost torque in
the 3600 rpm range and contributes to the engine's
broad, flat torque curve, which was desired for excel-
lent engine tractability, response and usable power
output.
The intake manifold is also cored with upper level
EGR passages for balanced cylinder to cylinder EGR
distribution.
The exhaust manifolds are log type with a cross-
over and are attached directly to the cylinder heads.
They are made from nodular cast iron.
DIAGNOSIS AND TESTING
EXHAUST SYSTEM
CONDITION POSSIBLE CAUSES CORRECTION
EXCESSIVE EXHAUST
NOISE (UNDER HOOD)1. Exhaust manifold cracked or broken. 1. Replace manifold.
2. Manifold to cylinder head leak. 2. Tighten manifold and/or replace gasket.
3. EGR Valve to manifold gasket leakage. 3. Tighten fasteners or replace gasket.
4. EGR Valve to EGR tube gasket
leakage.4. Tighten fasteners or replace gasket.
5. EGR tube to manifold tube leakage. 5. Tighten tube nut.
6. Exhaust flex-joint to manifold leak. 6. Tighten joint fasteners and/or replace
gasket.
7. Exhaust flex-joint. 7. Replace catalytic converter assembly.
8. Pipe and shell noise from front exhaust
pipe.8. Characteristic of single wall pipe.
EXCESSIVE EXHAUST
NOISE1. Leak at exhaust pipe joints. 1. Tighten clamps at leaking joints.
2. Burned or rusted out muffler assembly
or exhaust pipe.2. Replace muffler resonator tailpipe
assembly or exhaust pipe with catalytic
converter assembly.
3. Burned or rusted out resonator. 3. Replace muffler resonator tailpipe
assembly.
4. Restriction in exhaust system. 4. Remove restriction, if possible, or
replace as necessary.
5. Converter material in muffler. 5. Replace muffler and converter
assemblies. Check fuel injection and
ignition systems for proper operation.
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 3
GENERAL INFORMATION (Continued)
Page 1266 of 1938

REMOVAL AND INSTALLATION
EXHAUST PIPES, MUFFLERS AND TAILPIPES
REMOVAL
(1) Raise vehicle on hoist and apply penetrating
oil to clamp bolts and nuts of component being
removed.
(2) Loosen clamps and supports (Fig. 5) and (Fig.
4) from exhaust system to permit alignment of parts
during assembly.
(3) When removing tailpipe, raise rear of vehicle
to relieve body weight from rear springs to provide
clearance between pipe and rear axle parts.
(4) Clean ends of pipes or muffler to assure mat-
ing of all parts. Discard broken or worn insulators,
rusted clamps, supports and attaching parts.When
replacement is required on any component of
the exhaust system. It is important that origi-nal equipment parts (or their equivalent) be
used;
²To insure proper alignment with other parts in
the system.
²Provide acceptable exhaust noise levels and does
not change exhaust system back pressure that could
effect emissions and performance.
INSTALLATION
(1) Assemble pipes, muffler support and clamp
loosely to permit alignment of all parts.
(2) Beginning at front of system, align and clamp
each component to maintain position and proper
clearance with underbody parts.
(3) Tighten the clamp and support to the proper
torques and clearances (Fig. 4).
UPPER INTAKE MANIFOLDÐ2.4L ENGINE
REMOVAL
(1) Disconnect negative cable from battery.
(2) Disconnect air intake tube and resonator box
from throttle body and remove.
(3) Remove connector from throttle position sensor
(Fig. 6).
(4) Remove connector from idle air control motor
(Fig. 6).
(5) Remove connector from MAP sensor (Fig. 11).
Fig. 4 Exhaust System Components
Fig. 5 Band Clamp
11 - 4 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
Page 1267 of 1938

(6) Remove vacuum lines for purge solenoid and
PCV valve at intake manifold (Fig. 7).
(7) Remove vacuum lines for power brake booster
and speed control vacuum reservoir at upper intake
manifold fittings (Fig. 8).
(8) Remove throttle cable and speed control cable
(if equipped) from throttle lever (Fig. 9).
(9) Remove throttle cables from bracket by com-
pressing retaining tabs.
(10) Remove two top bolts from intake manifold to
rear support bracket and spacer (Fig. 10).
(11) Remove upper bolt from intake manifold to
front support bracket (Fig. 11).
(12) Remove dipstick.
(13) Remove dipstick tube.
CAUTION: Moving the dipstick tube will cause dam-
age to the sealer, causing an oil leak. Dipstick tube
must be sealed at cylinder block.
(14) Remove upper intake manifold bolts. Remove
upper intake manifold.CAUTION: Cover intake manifold to prevent foreign
material from entering engine.
Fig. 6 Throttle Body Electrical Connectors
Fig. 7 Vacuum Line Connections
Fig. 8 Vacuum Fitting at Rear of Upper Intake
Manifold
Fig. 9 Throttle Cable Attachment to Throttle Body
Fig. 10 Intake Manifold Rear Support Bracket
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 5
REMOVAL AND INSTALLATION (Continued)
Page 1268 of 1938

INSTALLATION
(1) Install new upper intake manifold gasket.
NOTE: Center outboard fastener is a double stud.
(2) Tighten upper intake manifold fasteners start-
ing at center and progressing outward in both direc-
tions. Tighten bolts to 28 N´m (250 in. lbs.). Repeat
this procedures until all fasteners are at specified
torque.
(3) Install dipstick tube. Seal tube to cylinder
block using MopartStud N' Bearing Mount Adhe-
sive. Tighten dipstick tube fastener to 12 N´m (105
in. lbs.)
(4) Install dipstick.
(5) Install upper bolt in intake manifold to front
support bracket (Fig. 11). Torque to 28 N´m (250 in.
lbs.).
(6) Install two top bolts at intake manifold to rear
support bracket making sure bracket to manifold
spacer is in place (Fig. 10). Tighten bolts to 28 N´m
(250 in. lbs.)
(7) Install throttle cables in bracket.
(8) Install throttle cable and speed control cable (if
equipped) to throttle lever.
(9) Install vacuum lines for power brake booster
and speed control vacuum reservoir at upper intake
manifold fittings.
(10) Install vacuum lines for purge solenoid and
PCV valve.
(11) Install electrical connectors for MAP sensor,
throttle position sensor, and idle air control motor.(12) Install air intake tube and resonator box to
throttle body.
(13) Connect negative cable to battery.
INTAKE MANIFOLD LOWERÐ2.4L ENGINE
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
SERVICE VEHICLES IN WELL VENTILATED AREAS
AND AVOID IGNITION SOURCES. NEVER SMOKE
WHILE SERVICING THE VEHICLE
To release fuel pressure, refer to the Fuel Delivery
System Pressure Release section of Group 14 Fuel
System for procedure.
REMOVAL
(1) Perform fuel system pressure release proce-
durebefore attempting any repairs.
(2) Remove upper intake manifold. Refer to proce-
dure in this section.
CAUTION: Cover intake manifold to prevent foreign
material from entering engine.
(3) Disconnect electrical connector from intake air
temperature sensor (Fig. 12).
(4) Remove fuel hose quick connect fitting from
the chassis tube (Fig. 13).Refer to Fuel Hoses,
Clamps and Quick Connect Fittings in the Fuel
Delivery Section of this Group.
WARNING: WRAP A SHOP TOWEL AROUND
HOSES TO CATCH ANY GASOLINE SPILLAGE.
Fig. 11 Intake Manifold Front Support Bracket and
Map Sensor
Fig. 12 Intake Air Temperature Sensor
11 - 6 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
REMOVAL AND INSTALLATION (Continued)
Page 1269 of 1938

(5) Drain cooling system. Refer to Group 7, Cool-
ing System for procedure.
(6) Remove heater, and upper radiator hoses at
intake manifold.
(7) Disconnect coolant temperature sensor (Fig.
14).
(8) Remove the accessory drive belt. Refer to
Accessory Drive belt Removal and Installation in
Group 7, Cooling System for procedure.
(9) Remove fasteners attaching generator bracket
to cylinder head, and block.
(10) Remove intake manifold center support
bracket bolts (Y bracket) (Fig. 15)
(11) Disconnect fuel injector harness.(12) Remove lower intake manifold fasteners (Fig.
16). Remove the manifold from engine.
(13) Inspect and clean manifold. Refer to Cleaning
and Inspection outlined in this section for proce-
dures.
INSTALLATION
If the following items were removed, install and
torque to:
²Fuel Rail Bolts 22 N´m (200 in. lbs.)
²Engine Outlet Connector Bolts 28 N´m (250 in.
lbs.)
²Coolant Temperature Sensor 7 N´m (60 in. lbs.)
²Intake Air Temperature Sensor 28 N´m (250 in.
lbs.)
(1) Using a new intake gasket, position intake
manifold on the engine and install retaining bolts.
Fig. 13 Fuel Line Quick Disconnect
Fig. 14 Coolant Temperature SensorÐ2.4L
Fig. 15 Intake Manifold Center Support Bracket
Fig. 16 Intake Manifold Fasteners
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 7
REMOVAL AND INSTALLATION (Continued)
Page 1270 of 1938

(2) Tighten intake manifold fasteners in the fol-
lowing sequence (Fig. 16). Torque to 23 N´m (200 in.
lbs.). Repeat this procedure until all bolts are at
specified torque.
(3) Install intake manifold center support bracket
bolts (Y bracket):
²Fastener to block 54 N´m (40 ft. lbs.)
²Fastener to intake 28 N´m (250 in. lbs.)
(4) Install fuel hose quick connector fitting to
chassis tubes.Refer to Fuel Hoses, Clamps and
Quick Connect Fittings in Group 14, Fuel Deliv-
ery.Push the fitting onto the chassis tube until it
clicks into place. Pull on the fitting to ensure com-
plete insertion.
(5) Reverse removal procedures 2 through 12 for
installation.
CAUTION: When using the ASD Fuel System Test,
the ASD relay and fuel pump relay remain energized
for 7 minutes or until the test is stopped, or until
the ignition switch is turned to the Off position.
(6) With the ignition key in ON position, access
the DRB scan tool ASD Fuel System Test to pressur-
ize the fuel system. Check for leaks.
EXHAUST MANIFOLDÐ2.4L ENGINE
REMOVAL
(1) Raise vehicle and disconnect exhaust pipe from
the exhaust manifold at the flex-joint.
(2) Disconnect Oxygen Sensor lead wire at the rear
exhaust manifold (Fig. 17).
(3) Remove the bolts attaching the manifold to the
cylinder head. Remove manifold (Fig. 17).
(4) Inspect and clean manifold. Refer to Cleaning
and Inspection outlined in this section for proce-
dures.
INSTALLATION
(1) Install exhaust manifold with a new gasket
and tighten attaching nuts in the order shown in
(Fig. 17) to 20 N´m (175 in. lbs.).
(2) Attach exhaust pipe to exhaust manifold and
tighten bolt to 28 N´m (250 in. lbs.).
(3) Connect heated oxygen sensor lead (Fig. 17).
INTAKE MANIFOLDÐ3.0L ENGINE
REMOVAL
(1) Perform fuel system pressure release proce-
dure(before attempting any repairs).Refer to
Group 14 Fuel System for procedure.
(2) Disconnect negative battery cable. Drain cool-
ing system. See Cooling System, Group 7.
(3) Remove air inlet resonator to throttle body
hose.
(4) Remove throttle cable and transaxle kickdown
linkage (Fig. 18).
(5) Remove automatic idle speed (AIS) motor and
throttle position sensor (TPS) wiring connectors from
throttle body (Fig. 19).
(6) Remove vacuum hose harness from throttle
body.
(7) Remove PCV and Brake booster hoses from
Air Intake Plenum.
(8) Remove Ignition Coil from Intake Plenum
(Fig. 20).
(9) Remove wiring connectors from coolant temper-
ature sensor (Fig. 21).
(10) Remove vacuum connections from Air Intake
Plenum vacuum connector.
(11) Remove fuel hose from fuel rail (Fig. 21).
WARNING: WRAP SHOP TOWELS AROUND HOSES
TO CATCH ANY GASOLINE SPILLAGE.
Fig. 17 Exhaust Manifold Attaching PointsÐ2.4L
Engine
Fig. 18 Throttle Cable Attachment
11 - 8 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
REMOVAL AND INSTALLATION (Continued)
Page 1271 of 1938
(12) Remove fasteners from Air Intake Plenum to
Intake Manifold (Fig. 22).(13) Remove Air Intake Plenum (Fig. 23).
(14) Cover intake manifold with suitable cover
when servicing (Fig. 24).
(15) Disconnect Fuel Injector wiring harness from
engine wiring harness.
Fig. 19 Electrical and Vacuum Connections to
Throttle Body
Fig. 20 Ignition Coil Removal
Fig. 21 Coolant Temperature Sensor Electrical
Connections
Fig. 22 Air Intake Plenum to Intake Manifold
Attaching Bolts
Fig. 23 Removing Air Intake Plenum
Fig. 24 Vacuum Connections for Fuel Rail and Fuel
Pressure Regulator
NSEXHAUST SYSTEM AND INTAKE MANIFOLD 11 - 9
REMOVAL AND INSTALLATION (Continued)
Page 1272 of 1938

(16) Remove fuel rail attaching bolts and lift fuel
rail assembly from intake manifold.
(17) Separate radiator hose from thermostat hous-
ing and heater hose from heater pipe.
(18) Remove nut and washer assemblies and
remove intake manifold (Fig. 25).
(19) Inspect and clean manifold. Refer to Cleaning
and Inspection outlined in this section for proce-
dures.
INSTALLATION
(1) Position new intake manifold gaskets on cylin-
der head and install intake (cross) manifold.
(2) Install nuts and washers and tighten in sev-
eral steps in order shown in (Fig. 26) to 20 N´m (174
in. lbs.).
(3) Make sure the injector holes are clean and all
plugs have been removed.
(4) Lube injector O-ring with a drop of clean
engine oil to ease installation.
(5) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports.
(6) Install the fuel rail attaching bolts and torque
to 13 N´m (115 in. lbs.).(7) Install fuel supply and the vacuum crossover
tube hold-down bolt and torque to 10 N´m (95 in.
lbs.).
(8) Remove covering from lower intake manifold
and clean surface.
(9) Place intake manifold gasketswith beaded
sealant side upon lower manifold. Put air intake in
place. Install attaching fasteners and tighten in sev-
eral steps in sequence shown (Fig. 27) to 13 N´m (115
in. lbs.).
Fig. 25 Intake and Exhaust Manifolds Ð 3.0L Engine
Fig. 26 Fastener Tightening Sequence for Intake
(Cross) Manifold
11 - 10 EXHAUST SYSTEM AND INTAKE MANIFOLDNS
REMOVAL AND INSTALLATION (Continued)