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MANIFOLD-INTAKE
DIAGNOSIS AND TESTING
INTAKE MANIFOLD LEAKS
An intake manifold air leak is characterized by lower than normal manifoldvacuum, rough idle, or engine misfire.
WARNING: USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING. DO NOT STAND IN ADIRECT LINE
WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELT OR THE FAN. DO NOT WEAR
LOOSE CLOTHING.
1. Start the engine.
2. Spray a small stream of water (Spray Bottle) at the suspected leak area.
3. If engine RPM’S change, the area of the suspected leak has been found.
4. Repair as required.
REMOVAL
NOTE: Care must be taken to protect the intake
manifold powder coating from scrapes and abra-
sions.
1. Perform the fuel system pressure release proce-
dure,before attempting any repairs.(Refer to 14
- FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE - FUEL SYSTEM PRESSURE
RELEASE PROCEDURE).
2. Disconnect negative battery cable.
3. Disconnect throttle body air inlet duct, IAT sensor,
CCV hose and remove air cleaner cover (Refer to
9 - ENGINE/AIR INTAKE SYSTEM - REMOVAL).
4. Disconnect throttle cable (2) from throttle cam.
Remove throttle cable from bracket and set aside.
5. Disconnect speed control cable from throttle cam
and set aside.
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6. Disconnect brake booster vacuum hose from the
intake manifold and set aside.
WARNING: WRAP A SHOP TOWEL AROUND FUEL
LINE TO CATCH ANY GASOLINE SPILLAGE.
7. Disconnect fuel line quick connect fitting from fuel
rail (Refer to 14 - FUEL SYSTEM/FUEL DELIV-
ERY/QUICK CONNECT FITTING - STANDARD
PROCEDURE).
8. Disconnect the following electrical connectors:
Left cylinder head fuel injectors
MAP sensor
Engine Coolant Temperature (ECT) Sensor
Idle Speed Control Sensor (ISC)
Throttle Position Sensor (TPS) (1)
Right cylinder head fuel injectors
9. Carefully separate the fuel injector harness push
pins from the intake manifold.
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10. Disconnect the purge solenoid hose from beneath
thethrottlebody.
11. Disconnect CCV hoses from left and right cylinder
head covers.
CAUTION: Care must be taken when removing the
No. nine cylinder inside intake manifold bolt. Fail-
ure to do so may result in personal injury or pos-
sible damage.
12. Remove the intake manifold bolts and intake man-
ifold (2).
13. Cover the intake manifold openings with a suit-
able cover when servicing to prevent any debris
from entering cylinder heads.
INSPECTION
1. Inspect manifold for cracks or other damage.
2. Inspect manifold sealing surfaces for damage.
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INSTALLATION
CAUTION: When cleaning the intake manifold and
cylinder head mating surfaces, do not use a metal
scraper because the surfaces could be cut or
ground. Instead, use a wooden or plastic scraper.
NOTE: Care must be taken to protect the intake
manifold powder coat from possible scrapes and
abrasions.
1. Clean gasket surfaces and remove covering from
intake manifold openings.
2. Carefully install the intake manifold gaskets (2) and
alignment pins (1).
3. Set the intake manifold in position on the engine.
Install intake manifold bolts and tighten initially to 1
Nꞏm (10 in. lbs.). Tighten bolts starting at the center
and working outward to 11 Nꞏm (95 in. lbs.).
4. Connect CCV hoses to left and right cylinder head
covers.
5. Connect fuel line to fuel rail. Pull backward on the
quick connect fitting to ensure complete insertion.
6. Connect the brake booster vacuum hose.
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7. Connect speed control cable to throttle linkage.
8. Connect the throttle cable housing to the bracket
and then attach the cable to the throttle linkage
9. Attach the purge solenoid hose to the underside of
the throttle body housing.
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10. Reconnect the following electrical connectors:
Left cylinder head fuel injectors
Engine Coolant Temperature (ECT) Sensor
MAP sensor
Idle Speed Control
Throttle Position Sensor
Right cylinder head fuel injectors
11. Install air cleaner cover assembly, connect throttle
body air inlet hose, CCV hose and connect the
Intake Air Temperature Sensor (Refer to 9 -
ENGINE/AIR INTAKE SYSTEM - INSTALLATION).
12. Connect negative battery cable.
13. With the Scan Tool, use the ASD Fuel System
Test to pressurize fuel system to check for leaks.
CAUTION: When using the ASD Fuel System Test,
the Auto Shutdown (ASD) relay will remain ener-
gized for 7 minutes or until the ignition switch is
turned to the OFF position, or Stop All Test is selected.
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MANIFOLD-EXHAUST
REMOVAL
NOTE: Care must be taken to protect the cylinder
head covers powder coating from scrapes and
abrasions. This procedure covers either the left or
right exhaust manifold.
1. Disconnect negative battery cable.
NOTE: When servicing the right exhaust manifold
it is necessary to remove the upper oil dip stick
tube fastener and position the tube aside.
2. Raise vehicle on hoist.
3. Loosen and remove the fasteners from the exhaust
pipe to exhaust manifold.
4. Separate exhaust pipe from the exhaust manifold.
5. Lower the vehicle.
6. Disconnect the spark plug wires from the spark
plugs and set aside.
7. Remove manifold heat shield from exhaust mani-
fold ,.
NOTE: Note the location of exhaust manifold studs
and bolts for proper installation.
8. Remove studs and bolts attaching manifold to cyl-
inder head and remove manifold ,.
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INSPECTION
Inspect exhaust manifolds for damage or cracks.
Check for distortion of the cylinder head mounting sur-
faces with a straightedge and feeler gauge.
INSTALLATION
NOTE: Care must be taken to protect the cylinder
head covers powder coating from scrapes and
abrasions. This procedure covers either the left or
right exhaust manifold.
1. Install new gasket and install exhaust manifold
Tighten attaching fasteners to 23 Nꞏm (200 in. lbs.)
,.
NOTE: When installing right exhaust manifold,
properly position the oil level indicator tube,
install fastener and tighten to the cylinder head
cover specification.
2. Install manifold heat shield and tighten attaching
fasteners to 6 Nꞏm (50 in. lbs.) ,.