GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Plenum/Upper Intake Manifold

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The Plenum is the top portion of the intake manifold. This portion must be removed before servicing the injector system.

REMOVAL & INSTALLATION



MFI Engines - Except 3.1L (VIN T)
  1. Disconnect the negative battery cable.
  2.  
  3. Tag and disconnect the vacuum lines.
  4.  
  5. Remove the EGR to plenum nuts.
  6.  
  7. Remove the two throttle body bolts.
  8.  
  9. Remove the throttle cable bracket bolts.
  10.  
  11. Remove the ignition wire plastic shield bolts.
  12.  
  13. Remove the plenum bolts.
  14.  
  15. Remove the plenum and gaskets from the engine.
  16.  

To install:
  1. Clean the gasket area, then install new gaskets.
  2.  
  3. Connect the plenum with the mounting bolts, then tighten them to 16 ft. lbs. (21 Nm).
  4.  
  5. Attach the ignition wire plastic shield bolts, then the throttle body bolts.
  6.  
  7. Tighten the throttle body bolts to 18 ft. lbs. (25 Nm).
  8.  
  9. Install the EGR to plenum nuts, then attach the throttle cable bracket bolts.
  10.  
  11. Hook up the vacuum lines, then connect the negative battery cable.
  12.  
  13. With the engine in the OFF position, make sure the accelerator pedal is free. Depress the pedal to the floor and release.
  14.  
  15. Reset the IAC pintle position:
    1. Turn the ignition ON .
    2.  
    3. Ground the engine diagnostic lead for about five seconds.
    4.  

  16.  

3.1L Engine (VIN T)

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air inlet duct at the throttle body and crankcase vent pipe at the valve cover grommet.
  4.  
  5. Disconnect the vacuum harness connector from the throttle body.
  6.  
  7. Remove the throttle cable bracket bolt.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Unfasten the plenum bolts and studs, then remove the plenum and gaskets. Discard the gaskets on the 3.1L (VIN T) engine

  1. Remove the throttle body attaching bolts. Remove the throttle body and gasket. Discard the gasket.
  2.  
  3. Remove the EGR transfer tube-to-plenum bolts. Remove the EGR transfer tube and gasket. Discard the gasket.
  4.  
  5. Remove the air conditioning compressor-to-plenum bracket attaching hardware. Remove the bracket.
  6.  
  7. Remove the plenum bolts and studs. Remove the plenum and gaskets. Discard the gaskets.
  8.  

To install:

Use care in cleaning old gasket material from machined aluminum surfaces. Sharp tool may damage gasket surfaces.

  1. Carefully, remove old gasket material from gasket sealing surfaces.
  2.  
  3. Install new plenum gaskets.
  4.  
  5. Install the plenum. Install the plenum bolts and studs. Tighten to 18 ft. lbs. (25 Nm).
  6.  
  7. Install the air conditioning compressor-to-plenum bracket and attaching hardware.
  8.  
  9. Install the EGR transfer tube with a new gasket. Install the EGR transfer tube bolts.
  10.  
  11. Install a new throttle body gasket. Install the throttle body and attaching bolts.
  12.  
  13. Install the throttle cable bracket bolt.
  14.  
  15. Connect the vacuum harness connector to the throttle body.
  16.  
  17. Connect the air inlet duct to the throttle body and crankcase vent pipe to the valve cover grommet.
  18.  
  19. Connect the negative battery cable.
  20.  
  21. With the ignition switch in the OFF position, ensure that the movement of the accelerator is free.
  22.  
  23. Perform the Idle Learn Procedure, as described in Routine Maintenance .
  24.  

3.1 L Engine (VIN M)

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the coolant, then disconnect the air inlet duct.
  4.  
  5. Remove the accelerator and cruise control cables at the throttle body accelerator control cable bracket.
  6.  
  7. Disconnect the fuel pipe clip at the accelerator cable bracket, then remove the bracket.
  8.  
  9. Disconnect the vacuum lines, matchmarking them for installation.
  10.  
  11. Remove the EGR valve.
  12.  
  13. Unfasten the heater inlet hose clamps at the heater inlet pipe.
  14.  
  15. Remove the ignition coil front bolts, then loosen the rear bolts.
  16.  
  17. Remove the alternator braces.
  18.  
  19. Disconnect the electrical connections to the IAC valve, MAF and TPS sensors.
  20.  
  21. Remove the upper intake manifold bolts and studs, then remove the assembly. Discard of the gaskets.
  22.  



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the SFI upper intake manifold

  1. Disassemble the throttle body from the upper intake manifold.
  2.  
  3. Remove the heater hoses from the upper intake manifold.
  4.  
  5. Disconnect the fuel pressure regulator vacuum line.
  6.  
  7. Clean the gasket surfaces.
  8.  

To install:
  1. Assemble the throttle body to the upper intake manifold.
  2.  
  3. Attach the heater hoses to the upper intake manifold.
  4.  
  5. Install new upper intake manifold gaskets, then connect the upper intake manifold by guiding the upper intake manifold heater hoses onto the heater inlet pipe.
  6.  
  7. Install the upper intake manifold bolts and studs, then tighten the bolts and studs to 18 ft. lbs. (25 Nm).
  8.  
  9. Attach the heater hose clamps at the heater inlet pipe.
  10.  
  11. Install the alternator braces.
  12.  
  13. Insert the ignition coil front and rear bolts, then tighten.
  14.  
  15. Install the EGR valve bolts.
  16.  
  17. Connect the vacuum lines previously matchmarked.
  18.  
  19. Connect the electrical connections to the sensors and valves.
  20.  
  21. Attach the alternator control cable bracket, then connect the fuel pipe clip at the accelerator control cable bracket. Attach all the control cables.
  22.  
  23. Adjust the accelerator cable and cruise cables.
  24.  
  25. Attach the air inlet duct.
  26.  
  27. Install the negative battery cable, then refill the coolant.
  28.  
  29. Start the engine and check the coolant level, fill if needed.
  30.  

 
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