GM Cadillac 1967-1989 Repair Guide

DFI Component Service

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REMOVAL & INSTALLATION



Throttle Body

See Figure 1

  1. Remove the air cleaner.
  2.  
  3. Disconnect the following electrical connectors and position them out of the way, ISC-Idle Speed Control, TPS-Throttle Position Sensor, and both injectors.
  4.  
  5. Remove both throttle return springs, cruise control and throttle linkage and downshift cable.
  6.  
  7. Disconnect the following hoses and lines from the rear of the throttle body: fuel inlet and return line, brake booster line, MAP hose and the AIR hose.
  8.  

Use flare nut wrench on all fuel lines.

  1. Remove the PCV, EVAP, and EGR hoses from the front of the throttle body.
  2.  
  3. Remove the three throttle body mounting screws and remove the throttle body and gasket.
  4.  
  5. Installation is the reverse of removal. Check the adjustment of the TPS and ISC after reinstallation.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Throttle body installation

MAP Sensor

See Figure 2

  1. Remove the instrument panel lower cover.
  2.  
  3. Working under the extreme right hand side of the instrument panel, disconnect the MAP hose from the sensor.
  4.  
  5. Disconnect MAP sensor electrical connector, being careful not to damage small gauge wires on the sensor side.
  6.  

The MAP sensor has a female connector on the sensor side and a male connector on the harness. The BARO connector is reversed.

  1. Remove the one screw securing MAP sensor to the bracket and remove the sensor.
  2.  
  3. Installation is the reverse of removal.
  4.  



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Fig. Fig. 2: MAP/BARO sensor installation

BARO Sensor
  1. Remove the instrument panel lower cover.
  2.  
  3. Remove the glove box liner.
  4.  
  5. Disconnect the BARO sensor electrical connector. Be careful not to damage the small gauge wires on the sensor side.
  6.  
  7. Working through the glove box opening, remove one screw securing MAP/BARO bracket to the instrument panel.
  8.  
  9. Remove one screw securing the BARO sensor and ground strap to the bracket.
  10.  
  11. Installation is the reverse of removal.
  12.  

Coolant Sensor
  1. Drain the radiator coolant until the level is below the level of the sensor.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the 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.

  1. Remove the alternator if necessary.
  2.  
  3. Disconnect the electrical pigtail and remove the sensor.
  4.  
  5. Installation is the reverse of removal.
  6.  

Coat the sensor threads with a non-hardening sealer during reinstallation.

Throttle Position Sensor

See Figure 3

On later models, TPS removal is accomplished by simply removing the two screws and lifting off the sensor.

  1. Remove the electrical connector from the TPS sensor.
  2.  
  3. Remove the throttle body assembly from the intake manifold to gain access to the spot welds on the bottom side that hold the TPS attaching screws. Invert the throttle body. Support it to prevent damage to the injector electrical connections. Drill completely through the TPS screw access holes (2) in the base of the throttle body, using a 5 / 16 in. drill bit.
  4.  
  5. Remove the two TPS attaching screws, lockwashers, and retainers. Then remove the TPS sensor from the throttle body, noting the location of the TPS lever in relation to the tang on the lever on the throttle shaft. Discard the TPS screws. New screws are supplied in service kits.
  6.  
  7. Installation is the reverse of removal. Adjust the TPS as necessary.
  8.  



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Fig. Fig. 3: Throttle position sensor removal on later models - DFI

Fuel Injector

See Figures 4, 5 and 6


WARNING
When removing the injectors, be careful not to damage the electrical connector pins (on top of the injector), the injector fuel filter and the nozzle. The fuel injector is serviced as a complete assembly ONLY. The injector is an electrical component and should not be immersed in any kind of cleaner.

  1. Remove the air cleaner. Relieve the fuel pressure.
  2.  
  3. At the injector connector, squeeze the two tabs together and pull straight up.
  4.  
  5. Remove the fuel meter cover, but leave the cover gasket in position.
  6.  
  7. Using a small pry bar or tool No. J-26868, carefully lift the injector until it is free from the fuel meter body.
  8.  
  9. Remove the small O-ring from the nozzle end of the injector. Carefully rotate the injector's fuel filter back-and-forth to remove it from the base of the injector.
  10.  

To install:
  1. Discard the fuel meter cover gasket.
  2.  
  3. Remove the large O-ring and back-up washer from the counterbore of the fuel meter body injector cavity. Discard the O-rings.
  4.  
  5. With the large end facing the injector, fit the fuel filter onto the nozzle end of the injector. Use a twisting motion to seat the filter against the base of the injector.
  6.  
  7. Coat a new small O-ring with automatic transmission fluid and press it onto the nozzle end of the injector until it meets the fuel filter.
  8.  
  9. Position the back-up washer in the top counterbore of the fuel meter body injector cavity.
  10.  
  11. Coat a new large O-ring with automatic transmission fluid and position it directly above the back-up washer. The O-ring must be seated properly in the cavity and should be flush with the top of the fuel meter body casting surface.
  12.  

The back-up washer and the large O-ring must be installed BEFORE the injector. Improper seating of the large O-ring will cause fuel leakage.

  1. Install the injector into the cavity. The raised lug on the injector base must align with the cast notch in the fuel meter body cavity. Press the injector until it is fully seated in the cavity (the electrical terminals of the injector should be parallel to the throttle shaft).
  2.  
  3. Install the fuel meter cover.
  4.  
  5. Installation of the remaining components is in the reverse order of removal. Start the engine and check for any fuel leakage around the throttle body.
  6.  



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Fig. Fig. 4: Removing the duel injector from the throttle body - DFI



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Fig. Fig. 5: Exploded view of the fuel injector - DFI



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Fig. Fig. 6: Installing the fuel injector into throttle body - DFI

Pressure Regulator
  1. Remove the air cleaner.
  2.  
  3. Remove the electrical connection on the injectors.
  4.  
  5. Remove the eight screws securing the pressure regulator assembly to the throttle body and remove the regulator.
  6.  
  7. Installation is the reverse of removal. Lubricate the new O-ring with Dexron®II® transmission fluid and install a new gasket.
  8.  

Fuel Meter Cover

See Figures 7 and 8

  1. Remove the air cleaner.
  2.  
  3. Disconnect the electrical connector from the fuel injector.
  4.  
  5. Remove the fuel meter-to-fuel meter body screws and lockwashers.
  6.  

When removing the fuel meter cover screws not the location of the two short screws.

  1. Remove the fuel meter cover and discard the gasket.
  2.  
  3. To install, use a new gasket and reverse the removal procedures.
  4.  



Click image to see an enlarged view

Fig. Fig. 7: Fuel meter cover removal - DFI



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Fig. Fig. 8: Installing the fuel meter cover - DFI

Fuel Meter Body
  1. Remove the fuel inlet and outlet nuts and gaskets from the fuel meter body.
  2.  
  3. Remove the three screws and lockwashers. Remove the fuel meter body from the throttle body assembly.
  4.  
  5. Remove the fuel meter body insulator gasket.
  6.  

Do not remove the center screw and staking at each end, holding the fuel distribution skirt in the throttle body. The skirt is an integral part of the throttle body and not serviced separately.

  1. Installation is the reverse of removal.
  2.  

Idle Speed Control (ISC) Motor
  1. Disconnect the electrical connector.
  2.  
  3. Remove the two ISC mounting screws.
  4.  
  5. Remove the ISC control.
  6.  
  7. Installation is the reverse of removal. Adjust the ISC motor if necessary.
  8.  

The idle speed control is specially calibrated at the factory and no attempt should be made to disassemble the unit. Do not immerse it in any type of cleaner. It must be removed before servicing or cleaning the throttle body. It is replaced only as an assembly.

CHECKS AND ADJUSTMENTS

Engine Idle Speed and Diagnostic Check
  1. Remove the air cleaner, start the engine, and warm the engine up to normal operating temperature (upper radiator hose hot). Turn A/C off.
  2.  
  3. Connect a tachometer to the engine and connect the digital voltmeter as follows:
    1. (+) lead the TPS harness test point which connects to pin A, (0.8 blue dark wire).
    2.  
    3. (-) lead to the TPS harness test point which connects to pin B, (0.8 black/white wire), circuit #4
    4.  
    5. Select the 2V DC scale.
    6.  

  4.  
  5. Open the set timing connect.
  6.  
  7. Retract the ISC motor by pressing the plunger (switch activated) in while the throttle is opened to approximately 1500 rpm. When the ISC motor fully retracts, disconnect the ISC connector, before releasing the throttle.
  8.  
  9. Jumper the ISC harness connector pins A and B together.
  10.  
  11. Under these conditions, the ISC plunger should not be touching the throttle lever. If contact is noted, adjust the ICS plunger (turn in) with pliers or suitable available special tool so that it is not touching the throttle lever.
  12.  
  13. The idle speed should now be 375 rpm (plus or minus 25 rpm) all except Calif. Eldorado/Seville cars (Calif. Eldorado/Seville - 400 rpm). Adjust throttle stop screw to proper rpm, if necessary. If the engine speed is not correct check that the throttle is not held off the minimum stop because of linkage pre-load. If necessary, adjust the throttle stop as described in the Minimum Air Rate Adjustment to obtain 375 rpm, all except Calif. Eldorado/Seville cars (Calif. Eldorado/Seville - 400 rpm).
  14.  
  15. Digital voltmeter should indicate 0.50 volts plus or minus 0.05 volts. If necessary, adjust Throttle Position Sensor:
    1. Remove throttle body assembly from the intake manifold to gain access to the spot welds on the bottom side holding the TPS attaching screws in place. Invert throttle body assembly and support the assembly to prevent damage to the injector electrical connections. Using a 5 / 16 in. drill bit, drill completely through TPS screw access holes in base of throttle body to be sure of removing the spot welds holding screws in place. Then loosen the screws just enough to permit rotation of the sensor.
    2.  
    3. With the engine idling at 375 rpm, all except non-Calif. Eldorado/Seville cars (Calif. Eldorado/Seville cars - 400 rpm) loosen the TPS mounting screws and position the TPS lever so that the voltmeter reads 0.50 volt plus or minus 0.05 volts.
    4.  
    5. Tighten the TPS mounting screws with the sensor in this position. Recheck the voltmeter reading when the screws are tight to make sure that the adjustment has not changed.
    6.  

  16.  
  17. Disconnect the test equipment, then engage all connections, including the set timing connector.
  18.  
  19. Turn the ignition off for 10 seconds. The ISC motor should move to its extended position.
  20.  
  21. The above procedure may have turned on the check engine light and may have set a trouble code. After the system is restored to normal operation, the check engine light will go out but the trouble code will remain as an intermittent problem. Enter diagnostics, clear the stored codes, and turn the ignition off for 10 seconds.
  22.  

ISC Motor Adjustment

Adjustment of the ISC motor is necessary to establish the initial position of the motor after it has been replaced. ISC motor adjustment may also be necessary if the throttle pedal ratchets when the ignition is turned OFF or ON .

  1. Remove the air cleaner, start the engine, and warm the engine up to normal operating temperature (upper radiator hose hot). Turn the A/C off.
  2.  
  3. Connect a tachometer to the engine.
  4.  
  5. Check the TPS adjustment as described in steps 2 through 7 in the TPS Adjustment section.
  6.  
  7. Unplug the set timing connector.
  8.  
  9. Disconnect the TPS connector.
  10.  
  11. Turn the ignition off for 10 seconds and observe the ISC plunger movement. It should fully extend.
  12.  
  13. When the ISC plunger is fully extended, disconnect the ISC connector. Jumper the ISC harness pins A and B together.
  14.  
  15. Reconnect the TPS and start the engine.
  16.  
  17. Under these conditions, engine idle speed should be 1500 rpm (plus or minus 100 rpm). If the engine speed is not correct, turn the ISC plunger to provide 1500 rpm.
  18.  
  19. Reconnect the ISC motor and repeat Steps 5-8. If the engine speed is too low, adjust the TPS as needed.
  20.  
  21. Disconnect the test equipment, then engage all wiring connections, including the set timing connector.
  22.  
  23. Turn the ignition off for 10 seconds. Start the engine and check the ISC motor for proper operation.
  24.  
  25. Turn the ignition off for 10 seconds. The ISC motor should move to its fully extended position.
  26.  
  27. The above procedure may have turned on the check engine light and may have set a trouble code. After the system is restored to its normal operation, the check engine light will go out but the trouble code will remain as an intermittent problem. Enter diagnostics, clear the stored codes, and turn the ignition off for 10 seconds.
  28.  

Minimum Air Rate Adjustment

This adjustment should be performed only when the throttle body parts have been replaced or when required to do so by the TPS adjustment.

  1. Remove the air cleaner, start the engine, and warm it up to normal operating temperature. Turn the A/C off.
  2.  
  3. Connect a tachometer to the engine.
  4.  
  5. Open the set timing connector.
  6.  
  7. Retract the ISC motor by pressing holding the plunger (switch-activated) in while the throttle is opened to approximately 1500 rpm. When the ISC motor fully retracts, disconnect the ISC connector before releasing the throttle.
  8.  
  9. Jumper the ISC harness connector pins A and B together.
  10.  
  11. Under these conditions, the ISC plunger should not be touching the throttle lever. If contact is noted, adjust the ISC motor as described under that heading.
  12.  
  13. The idle speed should now be 375 rpm (plus or minus 25 rpm) all except non-Calif. Eldorado/Seville cars (Calif. Eldorado/Seville - 400 rpm). Adjust throttle stop screw to proper rpm, if necessary. If the engine speed is not correct check that the throttle is not held off the minimum stop because of linkage pre-load. If necessary, adjust the throttle stop as described in the Minimum Air Rate Adjustment to obtain 375 rpm-all except non-Calif. Eldorado/Seville cars (Calif. Eldorado/Seville - 400 rpm).
  14.  
  15. Check the TPS adjustment as described under that heading.
  16.  
  17. Disconnect the test equipment, then engage all wiring connections, including the set timing connector.
  18.  
  19. Turn ignition off for 10 seconds. The ISC motor should move to its extended position.
  20.  
  21. The above procedure may have turned on the check engine light and may have set a trouble code. After the system is restored to normal operation, the check engine light will go out but the trouble code will remain as an intermittent problem. Enter diagnostics, clear the stored codes, and turn the ignition off for 10 seconds.
  22.  

 
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