Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Throttle Body

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See Figure 1

The throttle body injection unit is made up of 2 major casting assemblies. The top piece, or fuel meter body, contains the fuel injector and pressure regulator. The bottom piece, or throttle body, contains the throttle valve, IAC valve, TPS, and the vacuum manifold or tubes which supply manifold vacuum to various engine control solenoids.



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Fig. Fig. 1: Exploded view of the throttle body injection unit

REMOVAL & INSTALLATION



See Figures 2, 3 and 4

  1. Disconnect the negative battery cable and remove the air cleaner assembly.
  2.  
  3. Properly relieve the fuel system pressure. Refer to the procedure in this section.
  4.  
  5. Unplug the electrical connectors from the following components:
    1. Idle Air Control (IAC) valve
    2.  
    3. Throttle Position Sensor (TPS)
    4.  
    5. Fuel injector
    6.  

  6.  
  7. Remove the grommet (with the wires) from the throttle body.
  8.  
  9. Disconnect the throttle cable from the accelerator lever on the throttle body.
  10.  
  11. Label and disconnect the vacuum lines from the throttle body fittings.
  12.  
  13. Using a backup wrench to prevent stress and damage to the fittings, remove the fuel supply and return lines. Remove the O-rings from the line nuts and discard.
  14.  
  15. Remove the throttle body unit attaching bolts, then carefully remove the throttle body from the intake manifold.
  16.  
  17. Remove and discard the old gasket from the mating surface, being careful not to score the intake manifold surface. Place a clean rag or cloth over the opening to prevent debris from entering the intake manifold.
  18.  

To install:
  1. Thoroughly clean any remaining gasket material from the intake manifold and remove any old threadlock from the throttle body attaching bolt threads. Inspect the intake manifold opening for any loose parts or debris and make sure the sealing surfaces are not scored or damaged.
  2.  
  3. Position a new throttle body unit gasket onto the manifold flange, then install the unit. Apply a coat of Loctite® 242 or an equivalent threadlock to the attaching bolts, then install the bolts and tighten to 24 ft. lbs. (33 Nm).
  4.  
  5. If removed, install the fuel meter body attaching screws.
  6.  
  7. Even if they were not removed, torque the fuel meter body attaching screws to 35 inch lbs. (4 Nm).
  8.  
  9. Install new O-rings to the fuel supply and return lines, then install the lines and tighten to 19 ft. lbs. (25 Nm) using a backup wrench.
  10.  
  11. Connect the throttle cable to the accelerator lever on the throttle body. Make sure the cable does not hold the lever open when the accelerator pedal is in the released position.
  12.  
  13. Install the electrical connectors to the TPS, IAC valve and the fuel injector. Push in until a click is heard and give a slight tug on the connector to confirm positive engagement.
  14.  
  15. Connect the vacuum hoses from the EGR solenoid, canister purge solenoid and the MAP sensor to the TBI unit vacuum ports, as labeled during removal. Make sure the hoses are securely seated to prevent vacuum leaks.
  16.  
  17. Connect the negative battery cable.
  18.  
  19. Cycle the ignition a few times to prime the fuel system, then start the engine and check for fuel leaks.
  20.  
  21. Shut the engine OFF and install the air cleaner assembly. If damaged or deteriorated, replace the air cleaner assembly gasket.
  22.  



Click image to see an enlarged view

Fig. Fig. 2: Unplug the electrical connectors at these locations



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Fig. Fig. 3: Remove and discard the O-rings from fuel line nuts



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Fig. Fig. 4: Removing the throttle body assembly from the intake manifold

BASE IDLE SPEED ADJUSTMENT



For information concerning the adjustment of the base idle speed, refer to Idle Speed and Mixture Adjustments in General Information & Maintenance .

 
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