GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Intake Manifold Tuning Valve

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See Figure 1

The upper intake manifold on the CMFI engine is of a variable tuned split plenum design. The manifold uses a centrally mounted tuning valve to equalize pressure in the side-by-side inlet plenums. The valve is electronically operated by the computer control module.



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Fig. Fig. 1: Intake manifold tuning valve

REMOVAL & INSTALLATION



When installing the intake manifold tuning valve, you will need a new O-ring seal.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the tuning valve attaching screws.
  4.  
  5. Remove the tuning valve from the top of the upper intake manifold assembly.
  6.  
  7. Remove and discard the old O-ring seal.
  8.  

To install:
  1. Lubricate the new O-ring seal with clean engine oil.
  2.  
  3. Make sure the threads of the retaining screws are coated with Loctite(r)212, or an equivalent threadlocking compound.
  4.  
  5. Position the tuning valve to the upper intake manifold, then carefully thread the retaining screws.
  6.  

To avoid breaking the valve mounting ears, alternately tighten the attaching screws until they engage the mounting ear surface, then carefully tighten the screws to specification.

  1. Tighten the retaining screws to 18 inch lbs. (2 Nm).
  2.  
  3. Engage the valve electrical connector, then connect the negative battery cable.
  4.  

 
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