GM Prizm/Nova 1985-1993 Repair Guide

Fuel Injection Sensors and Controls

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CAUTION
The fuel system is under pressure. Before disconnecting any fuel lines or components release the fuel system pressure as outlined earlier in this section. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

REMOVAL & INSTALLATION



1988 VIN Code 5 Engines
COLD START INJECTOR

See Figure 1

  1. Test the resistance of the cold start injector before removing it. Disconnect its electrical lead and use an ohmmeter to measure resistance between the terminals. Correct resistance is 3-5 ohms allow for slight variations due to temperature.
  2.  
  3. If the injector must be replaced, release the fuel system pressure and disconnect the negative battery cable.
  4.  
  5. Remove the wiring connector at the injector if not already done for testing purposes.
  6.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Wrap the fuel pipe connection in a rag or towel. Remove the 2 union bolts and the cold start injector pipe with its gaskets. Loosen the union bolts at the other end as necessary.
  2.  
  3. Remove the 2 retaining bolts and remove the cold start injector with its gaskets.
  4.  
  5. When reinstalling, always use a new gasket for the injector. Install it with the injector and tighten the 2 mounting bolts to 7 ft. lbs. (84 inch lbs.).
  6.  
  7. Again using new gaskets, connect the cold start injector pipe to the delivery pipe (fuel rail) and to the cold start injector. Tighten the bolts to 13 ft. lbs.
  8.  
  9. Install the wiring to the cold start injector.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Start the engine and check for leaks.
  14.  



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Fig. Fig. 1: Cold start injector electrical schematic

FUEL PRESSURE REGULATOR

See Figure 2

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Remove the vacuum sensing hose from the fuel pressure regulator.
  4.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the fuel hose from the regulator.
  2.  



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Fig. Fig. 2: Location of fuel pressure regulator

  1. Remove the 2 retaining bolts and pull the regulator out of the fuel rail.
  2.  
  3. When reinstalling, the 2 retaining bolts are tightened to 5.5 ft. lbs. (65 inch lbs) Connect the 2 hoses (fuel and vacuum).
  4.  
  5. Start the engine and check carefully for leaks.
  6.  

MASS AIR FLOW SENSOR

See Figures 3, 4 and 5

The mass air flow sensor communicates with the ECM about the amount of air being taken into the engine. The intake air flow moves a trap door which is connected to a potentiometer. This variable load switch controls the amount of electricity sent to the ECM. Depending on the signal received, the ECM governs the fuel injectors to deliver the proportionally correct amount of fuel into the engine. The air box must be handled carefully during testing and/or replacement.

  1. Unplug the wiring connector at the mass air flow sensor.
  2.  
  3. Using an ohmmeter and the chart, measure the resistance between the terminals as indicated. The sensor must pass ALL tests; if any one is failed, the air sensor must be replaced. Note that the temperature related reading is measured in kilo-ohms. Don't forget to reset the meter to a higher scale.
  4.  
  5. If replacement is needed, label and disconnect the vacuum lines running to the sensor.
  6.  
  7. Remove the air cleaner hose.
  8.  
  9. Disconnect the wiring connector if not already done for testing purposes.
  10.  
  11. Remove the 4 nuts and the mass air flow sensor and its gasket.
  12.  
  13. When reinstalling, make absolutely sure that the air sensor and its gasket are correctly positioned. No air leaks are acceptable. Install and tighten the 4 nuts.
  14.  
  15. Install the wiring connector, the air cleaner hose and the vacuum hoses.
  16.  



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Fig. Fig. 3: Resistance chart for testing the mass air flow sensor



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Fig. Fig. 4: Mass air flow sensor schematic (above) and terminal identification



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Fig. Fig. 5: Removing the mass air flow sensor (A)

THROTTLE BODY

See Figures 6, 7, 8 and 9

  1. Release the fuel system pressure and disconnect the negative battery cable. Either drain the coolant from the throttle body by disconnecting a coolant hose or open the engine draincock until the fluid level is reduced.
  2.  


WARNING
Housepets and small animals are attracted to the odor and taste of engine coolant (antifreeze). It is a highly poisonous mixture of chemicals; special care must be taken to protect open containers and spillage.

  1. Disconnect the throttle return spring.
  2.  
  3. Disconnect the throttle cable.
  4.  
  5. Label and disconnect the vacuum hoses.
  6.  
  7. Carefully remove the throttle potion sensor wiring connector.
  8.  
  9. Remove the air cleaner hose.
  10.  
  11. Remove the water hoses from the air valve.
  12.  
  13. Remove the 2 bolts and 2 nuts and the throttle body with its gasket.
  14.  
  15. Wash and clean the cast metal parts with a soft brush and carburetor cleaner. Use compressed air to blow through all the passages and openings.
  16.  
  17. Check the throttle valve to see that there is NO clearance between the stop screw and the throttle lever when the throttle plate is fully closed.
  18.  
  19. Check the throttle position sensor (TPS). Insert a 0.47mm feeler gauge between the throttle stop screw and the lever. Connect an ohmmeter between terminal IDL and E2 . Loosen the 2 screws holding the TPS and gradually turn the TPS clockwise until the ohmmeter deflects, but no more. Secure the TPS screws at this point. Double check the clearance at the lever and stop screw.Additional resistance tests may be made on the TPS using the chart.
  20.  

To install:
  1. Place a new gasket in position and install the throttle body with its 2 nuts and 2 bolts. Make certain everything is properly positioned before securing the unit. Tighten the bolts to 16 ft. lbs.
  2.  
  3. Connect the water hoses to the air valve.
  4.  
  5. Install the air cleaner hose and the vacuum hoses.
  6.  
  7. Connect the wiring to the throttle position sensor.
  8.  
  9. Connect the accelerator cable and its return spring.
  10.  
  11. Refill the coolant to the proper level.
  12.  



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Fig. Fig. 6: Throttle body assembly. Arrow indicates throttle position sensor



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Fig. Fig. 7: Checking the throttle valve



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Fig. Fig. 8: Adjusting the throttle position sensor



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Fig. Fig. 9: Throttle position sensor resistance check

ELECTRONIC FUEL INJECTION (EFI) MAIN RELAY

See Figure 10

  1. The relay is located under the hood, behind the left headlight area. Turn the ignition ON without starting the engine and listen for a noise from the relay.
  2.  
  3. Turn the ignition off and remove the connector from the relay. Using the ohmmeter, check for continuity between terminals 1 and 3 .
  4.  
  5. Check that there is NO continuity between terminals 2 and 4 .
  6.  



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Fig. Fig. 10: Testing the EFI main relay

  1. Check that there is NO continuity between terminals 3 and 4 .
  2.  
  3. If the relay fails ANY of these tests, replace it.
  4.  

CIRCUIT OPENING RELAY

See Figure 11

  1. The relay is located behind the lower center of the dashboard, adjacent to the ECM. With the ignition off, unplug the connector and use an ohmmeter to check for continuity between terminals STA and E .
  2.  
  3. Check that there is continuity between terminals B and Fc .
  4.  



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Fig. Fig. 11: Checking continuity on the circuit opening relay

  1. Check that there is NO continuity between terminals B and Fp .
  2.  
  3. If the relay fails any test, it must be replaced.
  4.  

START INJECTOR TIME SWITCH

See Figure 12

  1. Remove the connector at the switch.
  2.  
  3. Use an ohmmeter to measure the resistance between terminals STA and STJ . Refer to the chart for the proper values.
  4.  



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Fig. Fig. 12: Resistance chart for checking the start injector time switch sensor

  1. If the time switch is to be replaced, drain the coolant from the system.
  2.  


WARNING
Housepets and small animals are attracted to the odor and taste of engine coolant (antifreeze). It is a highly poisonous mixture of chemicals; special care must be taken to protect open containers and spillage.

  1. Remove the switch and its gasket.
  2.  
  3. Install the new switch with a new gasket and tighten it to 25 ft. lbs.
  4.  
  5. Refill the coolant and attach the wiring connector to the switch.
  6.  

COOLANT TEMPERATURE SENSOR

See Figure 13

  1. Disconnect the wiring to the sensor.
  2.  
  3. Using an ohmmeter, measure the resistance across the terminals of the sensor. Refer to the chart for the correct resistance values. Note that the resistance will change as a function of the coolant temperature, not the air temperature.
  4.  



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Fig. Fig. 13: Resistance chart for testing the water temperature sensor

  1. If the sensor must be changed, the coolant must be drained. Do this only with the engine cold.
  2.  


WARNING
Housepets and small animals are attracted to the odor and taste of engine coolant (antifreeze). It is a highly poisonous mixture of chemicals; special care must be taken to protect open containers and spillage.

  1. Using the correct size wrench, remove the sensor by unscrewing it. Install the new sensor and tighten it.
  2.  
  3. Refill the coolant to the proper level.
  4.  
  5. Connect the wiring to the sensor.
  6.  

1989-90 VIN Code 6 Engines
COLD START INJECTOR

See Figure 14

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring at the injector.
  4.  
  5. Loosen and remove the fuel line at the injector.
  6.  


WARNING
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the 2 retaining bolts and remove the injector.
  2.  
  3. When reinstalling, position the new injector in the intake manifold, install the retaining bolts and tighten them to 7 ft. lbs. (84 inch lbs.)
  4.  
  5. Connect the fuel line, then connect the wiring harness to the injector.
  6.  
  7. Connect the negative battery cable.
  8.  



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Fig. Fig. 14: Location of electronic components - 1989-90 VIN Code 6 engine

FUEL PRESSURE REGULATOR

See Figures 14 and 15

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Disconnect the vacuum hose from the regulator.
  4.  



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Fig. Fig. 15: Fuel pressure regulator

  1. Disconnect the fuel return line from the regulator.
  2.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the 2 retaining bolts and remove the fuel pressure regulator.
  2.  
  3. When reinstalling, place the new regulator on the fuel rail, install the bolts and tighten them to 7 ft. lbs. (84 inch lbs.).
  4.  
  5. Connect the fuel return line, making sure the clamp is properly placed and secure.
  6.  
  7. Connect the vacuum hose, then connect the negative battery cable.
  8.  

THROTTLE BODY

See Figures 14 and 16

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner and intake duct assembly.
  4.  
  5. Disconnect the electrical wiring from the throttle switch.
  6.  
  7. Remove the 2 bolts holding the throttle cable bracket.
  8.  
  9. If so equipped, remove the transaxle shift cable (automatic transmission) and/or the cruise control cable.
  10.  
  11. Label and remove the vacuum hoses to the throttle body.
  12.  
  13. Remove the vacuum hose to the air valve.
  14.  
  15. Remove the 4 bolts holding the throttle body and carefully remove the throttle body.
  16.  
  17. When reinstalling, always use a new gasket between the throttle body and the intake. Do not use sealants of any kind on the gasket. Place the throttle body in position, install the 4 bolts and tighten them to 16 ft. lbs. Make very certain that the throttle body is properly placed before tightening the bolts; no air leaks are acceptable.
  18.  
  19. Install the throttle cable and its bracket.
  20.  
  21. If so equipped, reattach the transaxle cable and/or the cruise control cable.
  22.  
  23. Connect the vacuum hose to the air valve.
  24.  
  25. Connect the vacuum hoses to the throttle body.
  26.  
  27. Connect the electrical connector to the throttle switch and install the air cleaner and duct assembly.
  28.  
  29. Connect the negative battery cable.
  30.  



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Fig. Fig. 16: Throttle body assembly with throttle switch

THROTTLE SWITCH ADJUSTMENT

See Figures 16 and 17

This procedure may be performed on the car; removal of the throttle body is not required.

  1. With the ignition OFF , remove the electrical connector from the throttle switch.
  2.  
  3. Loosen the 2 small bolts holding the switch to the throttle body. Loosen them just enough to allow the switch to be moved if necessary, but no more.
  4.  
  5. Insert a 0.0276 in (0.70mm) feeler gauge between the throttle stop screw and the throttle lever. Connect an ohmmeter between terminals IDL and E2 on the switch.
  6.  



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Fig. Fig. 17: Adjusting the throttle switch

  1. Gradually turn the switch clockwise until the meter deflects, showing continuity; secure the sensor with the 2 screws.
  2.  
  3. Remove the feeler gauge and insert another of 0.80mm. The ohmmeter should show NO continuity with the larger gauge inserted.
  4.  
  5. Adjust the switch as necessary to gain the correct function for each feeler gauge. Tighten the screws when the correct position is achieved.
  6.  
  7. Connect the wiring harness to the throttle switch
  8.  

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

See Figure 18

Located on the firewall, this sensor advises the ECM of pressure changes in the intake manifold. It consists of a semi-conductor pressure converting element which converts a pressure change into an electrical signal. The ECM sends a 5 volt reference signal to the MAP sensor; the change in air pressure changes the resistance within the sensor. The ECM reads the change from its reference voltage and signals the injectors to react accordingly.



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Fig. Fig. 18: Cross section of MAP sensor

Replacing the MAP sensor simply requires disconnecting the vacuum hose and the electrical connector, and unbolting the sensor from the firewall. Inspect the vacuum hose over its entire length for any signs of cracking or splitting. The slightest leak can cause false messages to be send to the ECM.

MANIFOLD AIR TEMPERATURE (MAT) SENSOR

See Figure 14

The MAT sensor advises the ECM of changes in intake air temperature (and therefore air density). As air temperature of the intake varies, the ECM, by monitoring the voltage change, adjusts the amount of fuel injection according to the air temperature.

To replace the MAT sensor:

  1. Remove the air cleaner cover.
  2.  
  3. With the ignition OFF, disconnect the electrical connector.
  4.  
  5. Push the MAT sensor out from inside the air cleaner housing.
  6.  
  7. Install the new sensor, making sure it is properly placed and secure.
  8.  
  9. Connect the wiring harness, and replace the air cleaner cover.
  10.  

COOLANT TEMPERATURE SENSOR

See Figure 19

The coolant temperature sensor is located under the air cleaner assembly and behind the distributor. Its function is to advise the ECM of changes in engine temperature by monitoring the changes in coolant temperature. The sensor must be handled carefully during removal. It can be damaged (thereby affecting engine performance) by impact.



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Fig. Fig. 19: Coolant temperature sensor. Remember to coat the threads with sealant before reassembly

The sensor may be tested following the procedures listed previously for the 1988 VIN Code 5 engine. The temperature and resistance chart is the same. If the sensor must be replaced:


WARNING
Perform this procedure only on a cold engine.

  1. Relieve the pressure within the cooling system. It may be helpful to partially drain the block to lower the coolant level.
  2.  


WARNING
Housepets and small animals are attracted to the odor and taste of engine coolant (antifreeze). It is a highly poisonous mixture of chemicals; special care must be taken to protect open containers and spillage.

  1. Remove the air cleaner assembly.
  2.  
  3. With the ignition OFF, disconnect the electrical connector to the coolant temperature sensor.
  4.  
  5. Using the proper sized wrench, carefully unscrew the sensor from the engine.
  6.  
  7. Before reinstalling, coat the threads of the sensor with a sealant. Install the sensor and tighten it to 18 ft. lbs.
  8.  
  9. Reconnect the electrical connector. Install the air cleaner assembly.
  10.  
  11. Refill the coolant to the proper level.
  12.  

ELECTRONIC FUEL INJECTION (EFI) MAIN RELAY

See Figures 20 and 21

  1. The EFI relay is located on the fuse block (junction block) under the hood behind the left headlight. Test the function of the relay by turning the ignition ON and listening or feeling the relay. An operation noise should be heard (or felt) from the relay.
  2.  
  3. Turn the ignition OFF. Disconnect the connector from the relay and use an ohmmeter to check for continuity between relay terminals 3 and 4.
  4.  



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Fig. Fig. 20: Continuity check, EFI relay



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Fig. Fig. 21: Function check, EFI relay

  1. There should be NO continuity between terminals 1 and 2. If the relay fails either of these tests, replace it.
  2.  
  3. Using jumper wires, connect battery voltage across terminals 3 and 4 (Connect the battery positive (+) to terminal 4) and check terminals 1 and 2 for continuity. With 12 volts applied, continuity should be present.
  4.  
  5. Reinstall the relay in place.
  6.  

CIRCUIT OPENING RELAY

See Figures 22 and 23

  1. Remove the ECM cover under the center console. Remove the circuit opening relay and its wiring.
  2.  
  3. With the ignition OFF , disconnect the relay.
  4.  
  5. Using an ohmmeter, check that there is continuity between terminals STA and E1 .
  6.  
  7. Check that there is continuity between terminals B and FC .
  8.  
  9. Check that there is NO continuity between terminals B and FP . If the relay fails any of these checks, it must be replaced.
  10.  



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Fig. Fig. 22: Checking continuity of the circuit opening relay

  1. Using jumper wires, connect the battery positive (+) terminal to terminal STA and the battery negative terminal to terminal E1 . Use the ohmmeter to check that there is now continuity between terminals B and FP .
  2.  
  3. Change the jumper wires so that the positive terminal connects to terminal B and the negative connects to terminal FC . Check that there is now continuity between terminals B and FP .
  4.  
  5. If the relay fails either of these functional tests, it must be replaced.
  6.  



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Fig. Fig. 23: Checking the function of the circuit opening relay

1990-92 VIN Code 5 & 6 Engine
COLD START INJECTOR
  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Disconnect the wiring at the injector.
  4.  
  5. Loosen and remove the fuel line at the injector.
  6.  


WARNING
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the 2 retaining bolts and remove the injector.
  2.  
  3. When reinstalling, position the new injector in the intake manifold, install the retaining bolts and tighten them to 82 inch lbs. (9.3 Nm).
  4.  
  5. Connect the fuel line, then connect the wiring harness to the injector.
  6.  
  7. Connect the negative battery cable.
  8.  

FUEL PRESSURE REGULATOR

See Figure 24



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Fig. Fig. 24: Fuel rail and injectors - 1991-92

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Disconnect the vacuum hose from the regulator.
  4.  
  5. Disconnect the fuel return line from the regulator.
  6.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the 2 retaining bolts and remove the fuel pressure regulator.
  2.  
  3. When reinstalling, place the new regulator on the fuel rail, install the bolts and tighten them to 82 inch lbs. (9.3 ft. lbs.).
  4.  
  5. Connect the fuel return line, making sure the clamp is properly placed and secure.
  6.  
  7. Connect the vacuum hose, then connect the negative battery cable.
  8.  

THROTTLE BODY

See Figures 25 and 26

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner and intake duct assembly.
  4.  
  5. Disconnect the electrical wiring from the throttle switch.
  6.  
  7. Remove the 2 bolts holding the throttle cable bracket.
  8.  
  9. If so equipped, remove the transaxle shift cable (automatic transmission) and/or the cruise control cable.
  10.  
  11. Label and remove the vacuum hoses to the throttle body.
  12.  
  13. Remove the vacuum hose to the air valve.
  14.  
  15. Remove the 4 bolts holding the throttle body and carefully remove the throttle body.
  16.  
  17. When reinstalling, always use a new gasket between the throttle body and the intake. Do not use sealants of any kind on the gasket. Place the throttle body in position, install the 4 bolts and tighten them to 16 ft. lbs. (22 Nm). Make very certain that the throttle body is properly placed before tightening the bolts; no air leaks are acceptable.
  18.  
  19. Install the throttle cable and its bracket.
  20.  
  21. If so equipped, reattach the transaxle cable and/or the cruise control cable.
  22.  
  23. Connect the vacuum hose to the air valve.
  24.  
  25. Connect the vacuum hoses to the throttle body.
  26.  
  27. Connect the electrical connector to the throttle switch and install the air cleaner and duct assembly.
  28.  
  29. Connect the negative battery cable.
  30.  



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Fig. Fig. 25: Throttle body assembly - VIN Code 5 engine



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Fig. Fig. 26: Throttle body assembly - VIN Code 6 engine

THROTTLE POSITION SENSOR (TPS)

See Figure 27

VIN Code 5 Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the electrical connection for sensor.
  4.  
  5. Remove the 2 screws and remove the sensor.
  6.  

To install:
  1. Check that the throttle valve is fully closed.
  2.  
  3. Place the sensor on the throttle body. Turn the sensor clockwise and install the 2 screws loosely.
  4.  
  5. Adjust the throttle position sensor. Insert a 0.35mm or 0.0138 inch feeler gauge between the throttle stop screw and the lever. Connect an ohmmeter between terminals IDL and E2 . There should be continuity.
  6.  
  7. Insert a 0.39 mm (0.0232 inch) feeler gauge. There should be no continuity. Rotate the TPS as necessary, to adjust. Secure the TPS screws at this point.
  8.  
  9. Reconnect electrical connector. Start engine and check for proper operation.
  10.  



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Fig. Fig. 27: Throttle position sensor adjustment - VIN Code 5 engine

THROTTLE SWITCH (TS)

See Figures 28 and 29

VIN Code 6 Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect switch connector.
  4.  
  5. Hold the throttle valve opening angle at 45 degrees. Remove the 2 screws and remove the switch.
  6.  

To install:
  1. Place the throttle switch over the throttle valve shaft in correct alignment.
  2.  
  3. Install the 2 screws. Adjust the throttle switch. Insert a 0.70mm or 0.0276 in. feeler gauge between the throttle stop screw and the lever. Connect an ohmmeter between terminal IDL and E2 . There should be continuity.
  4.  
  5. Insert a 0.80 mm (0.0315 inch) feeler gauge. There should be no continuity. Rotate the switch as necessary to adjust. Secure the switch screws at this point.
  6.  
  7. Reconnect electrical connector. Start engine and check for proper operation.
  8.  



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Fig. Fig. 28: Throttle switch - VIN Code 6 engine



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Fig. Fig. 29: Throttle switch adjustment - VIN Code 6 engine

AUXILIARY AIR VALVE
VIN Code 5 Engine
  1. Remove the throttle body.
  2.  
  3. Remove the retaining screws and remove the air valve. Remove the O-ring and gasket.
  4.  
  5. Use a new O-ring and/or gasket; install the air valve to the throttle body.
  6.  
  7. Reinstall the throttle body.
  8.  

AIR VALVE

See Figure 30

VIN Code 6 Engine
  1. Remove the throttle body as outlined earlier in this section.
  2.  
  3. Remove the retaining screws and remove the air valve. Remove the O-ring and gasket.
  4.  
  5. Use a new O-ring and/or gasket; install the air valve to the throttle body.
  6.  
  7. Reinstall the throttle body.
  8.  



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Fig. Fig. 30: Air valve - VIN Code 6 engine

DASH POT REPLACEMENT

See Figure 31

  1. Remove the 2 retaining screws and remove the dashpot from the throttle body.
  2.  
  3. Installation is the reverse of removal.
  4.  
  5. Adjust the dashpot may be adjusted
  6.  



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Fig. Fig. 31: Dash pot location

DASH POT ADJUSTMENT

See Figure 32

  1. Run engine to normal operating temperature.
  2.  
  3. Check engine idle speed and adjust if necessary. Idle speed adjustment is 800 rpm (VIN 5), 700 rpm (VIN 6) in NEUTRAL , manual transaxle, and 800 rpm (VIN 5), 700 rpm (VIN 6) in DRIVE , automatic transaxle.
  4.  
  5. Connect a tachometer to IG terminal of the check connector.
  6.  
  7. Jumper terminal TE1 to E1 (VIN 6) of the check connector.
  8.  
  9. Disconnect the EGR VSV connector (VIN 6) (California Only).
  10.  
  11. Remove dash pot cap and filter and separator.
  12.  
  13. Maintain engine speed at 2,500 rpm (VIN 5), 3,000 rpm (VIN 6), and plug the VTV hole in dash pot.
  14.  
  15. Release the throttle valve and check dash pot rpm setting. Dash pot setting speed is 1,800 rpm (VIN 5), 1,500 rpm (VIN 6). If not within specifications, adjust the stop screw on the throttle shaft.
  16.  
  17. With dash pot rpm set, remove plug from VTV hole and check that the engine speed returns to idle in about 1 second. If longer than 2 seconds or less that 1 second, replace dash pot.
  18.  



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Fig. Fig. 32: Dash pot

1993 VIN Code 6 & 8 Engines
THROTTLE BODY
  1. Relieve the fuel system pressure as outlined in this section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Disconnect the accelerator cable and cruise control cable, if equipped, from the air cleaner clip.
  6.  
  7. Disconnect and tag the Intake Air Temperature sensor (IAT) electrical connector.
  8.  
  9. Disconnect the 4 air cleaner cap clips.
  10.  
  11. Remove the air cleaner hose and cap from the throttle body.
  12.  
  13. Disconnect the accelerator cable from the throttle body.
  14.  
  15. Remove the 2 nuts and disconnect the TV cable from the throttle body, if equipped with automatic transaxle.
  16.  
  17. Disconnect the 2 EGR vacuum hoses, on California specification vehicles only.
  18.  
  19. Disconnect the 1 evaporative (EVAP) emissions hose.
  20.  
  21. Disconnect the throttle position sensor and idle air control valve electrical connectors.
  22.  
  23. Remove the 2 bolts and 2 nuts and remove the throttle body and gasket from the intake manifold.
  24.  

To install:
  1. Install a new gasket, then throttle body and torque the bolts evenly (in a X-pattern) to 16 ft. lbs. (22 Nm).
  2.  
  3. Connect the throttle position sensor and idle air control valve electrical connectors.
  4.  
  5. Connect the 1 evaporative (EVAP) emissions hose.
  6.  
  7. Connect the 2 EGR vacuum hoses, on California specification vehicles only.
  8.  
  9. Connect the TV cable to the throttle body, if equipped with automatic transaxle. Adjust as necessary. Refer to Drive Train for TV cable adjustment.
  10.  
  11. Install the air cleaner hose and cap to the throttle body.
  12.  
  13. Connect the 4 air cleaner cap clips.
  14.  
  15. Connect the Intake Air Temperature sensor (IAT) electrical connector.
  16.  
  17. Connect the accelerator cable and cruise control cable, if equipped, to the air cleaner clip.
  18.  
  19. Connect the negative battery cable.
  20.  

FUEL PRESSURE REGULATOR

See Figure 33

  1. Release the fuel system pressure and disconnect the negative battery cable.
  2.  
  3. Disconnect the vacuum hose from the regulator.
  4.  
  5. Disconnect the fuel return line from the regulator.
  6.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the 2 retaining bolts and remove the fuel pressure regulator.
  2.  
  3. When reinstalling, place the new regulator on the fuel rail, install the bolts and tighten them to 82 inch lbs. (9.3 ft. lbs.).
  4.  
  5. Connect the fuel return line, making sure the clamp is properly placed and secure.
  6.  
  7. Connect the vacuum hose, then connect the negative battery cable.
  8.  



Click image to see an enlarged view

Fig. Fig. 33: Removing the fuel pressure regulator

IDLE AIR CONTROL VALVE

See Figure 34

  1. Remove the throttle body.
  2.  
  3. Remove the retaining screws and remove the air valve. Remove the gasket.
  4.  
  5. Use a new gasket and install the air valve to the throttle body.
  6.  
  7. Reinstall the throttle body.
  8.  



Click image to see an enlarged view

Fig. Fig. 34: Removing the Idle Air Control (IAC) valve

THROTTLE POSITION SENSOR (TPS)

See Figure 35

VIN Code 5 Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the electrical connection for sensor.
  4.  
  5. Remove the 2 screws and remove the sensor.
  6.  

To install:
  1. Check that the throttle valve is fully closed.
  2.  
  3. Place the sensor on the throttle body. Turn the sensor clockwise and install the 2 screws loosely.
  4.  
  5. Adjust the throttle position sensor. Insert a 0.35mm or 0.0138 inch feeler gauge between the throttle stop screw and the lever. Connect an ohmmeter between terminals IDL and E2 . There should be continuity.
  6.  
  7. Insert a 0.59 mm (0.0232 inch) feeler gauge. There should be no continuity. Rotate the TPS , necessary to adjust. Secure the TPS screws at this point.
  8.  
  9. Reconnect electrical connector. Start engine and check for proper operation.
  10.  



Click image to see an enlarged view

Fig. Fig. 35: Throttle position sensor

 
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