GM Camaro/Firebird 1993-1998 Repair Guide

Intake Manifold

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REMOVAL & INSTALLATION



When servicing all vehicles, be absolutely sure to mark vacuum hoses and wiring so that these items may be properly reconnected during installation. Also, when disconnecting fitting lines (fuel lines, power brake vacuum lines, transmission and engine cooler lines, etc.), always use two flare nut (or line) wrenches. Hold the wrench on the large fitting with pressure on the wrench as if you were tightening the fitting (clockwise), THEN loosen and disconnect the smaller fitting from the larger fitting. If this is not done, damage to the line will result. Always relieve fuel system pressure before disconnecting lines.


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

3.4L Engine
UPPER MANIFOLD

See Figures 1 and 2

  1. Disconnect the negative battery cable. Relieve the fuel system pressure.
  2.  
  3. Drain the coolant into a suitable container.
  4.  
  5. Remove the throttle body air duct.
  6.  
  7. Detach the fuel rail injector wiring harness connection.
  8.  
  9. Remove the wiring harness retaining nut and position the harness aside.
  10.  
  11. Remove the accelerator cable bracket bolts/screws, bracket and cables from the throttle body assembly.
  12.  
  13. Detach the fuel pipe connectors. Unfasten the fuel pipe bracket bolts/screws. Remove the fuel pipe hold-down plate bolt/screw, then remove the fuel pipe assembly and position out of the way.
  14.  
  15. Disconnect the coolant hoses from the throttle body assembly.
  16.  
  17. Remove the fuel rail stud.
  18.  
  19. Disconnect the fuel pressure regulator vacuum hose.
  20.  
  21. Detach the electrical connectors from the Idle Air Control (IAC), Throttle Position (TP) and Manifold Absolute Pressure (MAP) sensors and the evaporative emission canister purge solenoid valve.
  22.  
  23. Use compressed air to blow all dirt from the injector bores.
  24.  
  25. Remove the fuel rail assembly.
  26.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the fuel rail assembly

  1. If equipped, remove the vacuum harness assembly.
  2.  
  3. Unfasten the EGR flexible pipe bolts/screws and reposition the pipe and gasket.
  4.  
  5. Remove the upper intake manifold bolts, then remove the manifold and gasket Discard the old gaskets and clean the mating surfaces.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Upper intake manifold mounting

To install:
  1. Position a new gasket, then install the manifold. Tighten the bolts to 18 ft. lbs. (25 Nm).
  2.  
  3. Install the EGR pipe. Use a new gasket and wrap the bolt threads with Teflon tape. Tighten the bolts to 19 ft. lbs. (26 Nm). The gasket must be installed with the text "tube side" facing the tube.
  4.  
  5. Install the vacuum harness.
  6.  

Do not press on the regulator cover or piedmont valve when installing the fuel rail.

  1. Install the fuel rail. Lightly lubricate the fuel injector O-rings using clean engine oil. Install the injectors of the fuel rail into the bores of the manifold. Carefully press on the fuel rail with the palms of your hands until the injectors are fully seated.
  2.  
  3. Install the fuel rail stud and tighten to 18 ft. lbs. (25 Nm).
  4.  
  5. Engage the wiring connectors to the Idle Air Control (IAC), Throttle Position (TP) and Manifold Absolute Pressure (MAP) sensors and the evaporative emission canister purge solenoid valve.
  6.  
  7. Connect the fuel pressure regulator vacuum hose. Install the fuel rail wiring harness retaining nut.
  8.  
  9. Attach the fuel pipe assembly to the fuel rail. Slide the fuel line hold-down plate over the fuel pipe.
  10.  
  11. Apply Teflon sealant to the fuel pipe hold-down plate bolt/screw and tighten to 18 ft. lbs. (25 Nm). Install the fuel pipe bracket bolts/screws.
  12.  
  13. Install the accelerator cable bracket, bolts/screws and cables. Tighten the accelerator cable bracket bolts/screws to 90 inch lbs. (10 Nm). Tighten the fuel pipe bracket-to-front brace bolt/screw to 71 inch lbs. (8 Nm) and the fuel pipe bracket-to-intake manifold assembly bolt/screw to 89 inch lbs. (10 Nm).
  14.  
  15. Attach the fuel pipe and fuel injector electrical connections.
  16.  
  17. Connect the coolant hoses to the throttle body assembly.
  18.  
  19. Install the throttle body air duct.
  20.  
  21. Fill the coolant system.
  22.  
  23. Connect the negative battery cable, then start the engine and check for leaks.
  24.  

LOWER MANIFOLD

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the upper intake manifold.
  4.  
  5. Remove the valve covers.
  6.  
  7. Disconnect the upper radiator hose and the heater hose from the lower intake manifold.
  8.  
  9. Detach wiring harness ground leads.
  10.  
  11. Unfasten the lower manifold bolts/screws and nuts. Remove the lower manifold and gaskets. Discard the old gaskets and clean the sealing surfaces of the manifold and engine.
  12.  

To install:
  1. Install new lower intake manifold gaskets.
  2.  
  3. Apply a 3 / 16 in. (5mm) bead of RTV sealant at the engine block to manifold mating surface.
  4.  
  5. Install the intake manifold and secure with the retaining bolts. Tighten the bolts in sequence to 22 ft. lbs. (30Nm).
  6.  



Click image to see an enlarged view

Fig. Fig. 3: Lower intake manifold bolt torque sequence for 3.4L engine

  1. Attach the wiring harness ground leads.
  2.  
  3. Connect the upper radiator hose and the heater hose.
  4.  
  5. Install the valve covers.
  6.  
  7. Install the upper intake manifold.
  8.  
  9. Connect the negative battery cable.
  10.  

3.8L Engine

See Figures 4 and 5

UPPER MANIFOLD
  1. Disconnect the negative battery cable. Relieve the fuel system pressure.
  2.  
  3. Drain the coolant into a suitable container.
  4.  
  5. Remove the serpentine drive belt.
  6.  
  7. If necessary, remove the transmission fluid level indicator.
  8.  
  9. Remove the alternator and the serpentine drive belt tensioner.
  10.  
  11. Remove the Manifold Absolute Pressure (MAP) sensor and vacuum source from the upper intake manifold.
  12.  
  13. Remove the evaporative emission canister purge solenoid valve.
  14.  
  15. Remove the fuel pressure regulator and canister purge harness.
  16.  
  17. Remove the Idle Air Control (IAC) valve from the upper intake manifold.
  18.  
  19. Disconnect the fuel lines from the fuel rail.
  20.  
  21. Remove the accelerator control cable bracket bolts/screws, bracket and accelerator control cables from the throttle body.
  22.  
  23. Remove the ignition coil pack/control module assembly.
  24.  
  25. Disconnect the brake booster hose from the upper manifold.
  26.  
  27. Remove the alternator brace from the upper manifold.
  28.  
  29. Detach the electrical connectors from the idle air control, throttle position, mass airflow and intake air temperature sensors.
  30.  
  31. Unfasten the wiring harness from the rosebud clips at the fuel rail.
  32.  
  33. Remove the air cleaner, outlet rear duct and resonator duct.
  34.  
  35. If necessary, remove the throttle body from the upper intake manifold.
  36.  
  37. Remove the EGR valve outlet pipe.
  38.  

The thermostat must be removed to get to the "hidden" bolt located under the housing. This bolt retains the upper and lower manifolds.

  1. Remove the thermostat and thermostat housing.
  2.  
  3. Detach the electrical connectors from the fuel injectors. Clean the fuel injector bores using compressed air.
  4.  
  5. Unfasten the fuel rail nuts, then remove the fuel rail.
  6.  



Click image to see an enlarged view

Fig. Fig. 4: Fuel rail mounting - 3.8L engine

  1. Unfasten the upper intake manifold retaining bolts/screws, then remove the upper manifold and gasket. Discard the gasket and clean the mating surfaces and bolt threads.
  2.  



Click image to see an enlarged view

Fig. Fig. 5: Exploded view of the upper and lower intake manifolds

To install:
  1. Position a new gasket, then install the upper intake manifold. Tighten the bolts as follows:
    1. Tighten the ten vertical intake manifold bolts/screws 1-10 to 11 ft. lbs. (15 Nm) using the sequence in the accompanying figure.
    2.  
    3. Tighten the two coolant outlet bolts/screws to 20 ft. lbs. (27 Nm).
    4.  
    5. Tighten the side bolts/screws to 22 ft. lbs. (30 Nm).
    6.  

  2.  
  3. Install the fuel rail:
    1. Lightly lubricate the fuel injector O-rings using clean engine oil.
    2.  
    3. Install the injectors into the bores of the manifold.
    4.  
    5. Carefully press the fuel rail with the palms your hands until the injectors are properly seated.
    6.  

  4.  
  5. Install the fuel rail nuts and tighten to 89 inch lbs. (10 Nm). Attach the fuel injector electrical connectors.
  6.  
  7. Attach install the thermostat and thermostat housing.
  8.  
  9. Install the EGR valve outlet pipe.
  10.  
  11. If necessary, install the throttle body to the intake manifold.
  12.  
  13. Install the air cleaner, resonator duct and air cleaner outlet duct.
  14.  
  15. Fasten the wiring harness to the rosebud clips at the fuel rail.
  16.  
  17. Attach the electrical connectors to the idle air control, throttle position, mass airflow and intake air temperature sensors.
  18.  
  19. Install the alternator brace.
  20.  
  21. Connect the brake booster hose to the upper intake manifold.
  22.  
  23. Install the ignition control module.
  24.  
  25. Install the accelerator cable bracket, bolts/screws and accelerator control cables to the throttle body. Tighten the bracket bolts/screws to 89 inch lbs. (10 Nm).
  26.  
  27. Connect the fuel lines to the fuel rail.
  28.  
  29. Install the IAC valve to the upper intake manifold.
  30.  
  31. Install the fuel pressure regulator and the canister purge harness. Install the evaporative emissions canister purge solenoid valve.
  32.  
  33. Install the MAP sensor and vacuum source to the upper intake manifold.
  34.  
  35. Install the serpentine drive belt tensioner.
  36.  
  37. Install the alternator.
  38.  
  39. If necessary, install the transmission level indicator.
  40.  
  41. Install the serpentine drive belt.
  42.  
  43. Fill the coolant system.
  44.  
  45. Connect the negative battery cable, then start the engine and check for leaks.
  46.  

LOWER MANIFOLD
  1. Disconnect the negative battery cable.
  2.  

There are two bolts which are hidden under the upper manifold. They are located in the front and left rear corners of the lower manifold. Its necessary to remove the upper manifold to service the lower manifold.

  1. Remove the upper intake manifold.
  2.  
  3. Remove the rocker arm (valve) covers.
  4.  
  5. Remove the Engine Coolant Temperature (ECT) sensor.
  6.  
  7. Unfasten the lower intake manifold bolts/screws, then remove the manifold, gaskets and seals. Discard the gaskets and seals.
  8.  
  9. Thoroughly clean the gasket mating surfaces.
  10.  

To install:
  1. Install new gaskets and seals. Apply GM part no. 12345336 or equivalent to the front and rear manifold seals. Coat the bolt threads with GM part no. 12345493, or equivalent.
  2.  
  3. Position the lower manifold and install the retaining bolts/screws. The two lower intake manifold bolts/screws are located under the upper intake manifold (right front and left rear corners) and must be installed before upper manifold installation. Tighten the manifold bolts, in sequence, to 11 ft. lbs. (15 Nm).
  4.  
  5. Install the ECT sensor.
  6.  
  7. Install the valve covers and the upper intake manifold.
  8.  
  9. Connect the negative battery cable.
  10.  

5.7L Engine

See Figures 6 through 12

  1. Disconnect the negative battery cable. Relieve the fuel system pressure.
  2.  
  3. Remove the air duct. Drain the coolant system.
  4.  
  5. Unplug the connectors from the fuel injectors. Lay the wiring harnesses aside.
  6.  
  7. Disconnect the control cables from the throttle body.
  8.  
  9. Remove the secondary air injection diverter valve hoses.
  10.  
  11. Detach the fuel pipe connectors from the fuel rail. Remove the fuel rail bolts/screws.
  12.  
  13. Detach the fuel pressure regulator vacuum tube.
  14.  
  15. Remove the fuel rail from the intake manifold and position aside.
  16.  



Click image to see an enlarged view

Fig. Fig. 6: Fuel rail and throttle body mounting - 5.7L engine

  1. Disconnect the vacuum and crankcase vent hoses.
  2.  
  3. Remove the EGR valve control valve relay nut and control valve relay.
  4.  
  5. Remove the emission canister purge solenoid bracket nut and solenoid.
  6.  
  7. Remove the EGR nuts, then remove the valve. Remove the EGR valve pipe nuts and studs.
  8.  
  9. Remove the secondary air injection pipe fitting, nuts and pipe from the intake and right exhaust manifold.
  10.  
  11. Remove the alternator rear brace.
  12.  
  13. Unplug the hoses and electrical connections from the throttle body. Remove the throttle body and gasket.
  14.  
  15. Remove the manifold bolt and studs. Remove the intake manifold and gaskets. Discard the gaskets and thoroughly clean the gasket mating surfaces, bolt and stud threads.
  16.  



Click image to see an enlarged view

Fig. Fig. 7: Unfasten the intake manifold mounting bolts ...



Click image to see an enlarged view

Fig. Fig. 8: ... then remove the intake manifold from its mounting



Click image to see an enlarged view

Fig. Fig. 9: Remove and discard the intake manifold gasket



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Fig. Fig. 10: Carefully clean the gasket mating surfaces, being sure not to gouge the aluminum, possibly causing leaks



Click image to see an enlarged view

Fig. Fig. 11: Exploded view of the intake manifold - 5.7L engine

To install:
  1. Make sure the sealing surfaces are clean.
  2.  
  3. Apply a 3 / 16 in. (5mm) bead of RTV sealant on the front and rear ridge of the cylinder block.
  4.  
  5. Install the new gaskets on the cylinder heads. Hold the gaskets in place by extending the RTV bead up onto the gasket ends.
  6.  
  7. Install the intake manifold along with the intake manifold bolts. Tighten bolts in sequence to 71 inch lbs. (8 Nm) on the first pass and 35 ft. lbs. (48 Nm) on the second pass.
  8.  



Click image to see an enlarged view

Fig. Fig. 12: Intake manifold bolt tightening sequence for 5.7L LT1 engines

  1. Install the throttle body, tightening the throttle body bolts to 18 ft. lbs. (26 Nm). Engage all cable, hose and wiring connections on the throttle body.
  2.  
  3. Install the alternator rear brace.
  4.  
  5. If equipped, install the accelerator control/cruise control servo cable adjuster. Install the accelerator cable bracket and tightening the retaining screws to 90 inch lbs. (10 Nm). Connect the cables.
  6.  
  7. Install the secondary air injection pipe and nuts. Tighten the exhaust manifold fitting to 41 ft. lbs. (55 Nm).
  8.  
  9. Install the EGR valve pipe studs and nuts. Install the EGR valve and nuts and the control valve relay and nuts. Tighten as follows:
    1. EGR valve pipe studs to 53 inch lbs. (6 Nm).
    2.  
    3. EGR valve pipe nuts, valve nuts and control valve relay nut to 18 ft. lbs. (25 Nm).
    4.  

  10.  
  11. Install the emission canister purge solenoid and bracket bolt/screw. Tighten to 53 inch lbs. (6 Nm).
  12.  
  13. Connect the vacuum and crankcase vent hoses.
  14.  
  15. Install the fuel rail, fuel pressure regulator vacuum tube, and fuel rail bolts/screws. Tighten to 15 ft. lbs. (20 Nm). Attach the fuel pipe connectors to the fuel rail.
  16.  
  17. Connect the secondary air injection diverter valve hoses.
  18.  
  19. Install the left and right wiring harnesses and engage the wiring harness connectors.
  20.  
  21. Install the air duct. Connect the negative battery cable. Fill the cooling system.
  22.  

 
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