Mitsubishi Eclipse 1990-1998 Repair Guide

Evaporative Emission Control System

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OPERATION



See Figure 1

The function of this control system is to prevent the emissions of gasoline vapors from the fuel tank into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes to a charcoal canister. There they are temporarily held until they can be drawn into the intake manifold when the engine is running and burned the combustion process during engine operation. This action prevents excessive pressure buildup in the fuel tank.



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Fig. Fig. 1: Typical evaporative emission control system schematic

The system also prevents fuel spillage in the event of an accidental roll over of the vehicle. All vehicles have a roll over (two-way) valve installed in-line above the tank to release fuel tank pressure to the canister and to prevent fuel from leaking in the event of an accidental vehicle roll over.

Charcoal Canister

See Figure 2

A sealed, maintenance free charcoal canister is used on all vehicles. The fuel tank vents lead to the canister. Fuel vapors are temporarily held in the canister's activated charcoal until they can be drawn into the intake manifold and burned in the combustion chamber. There is no scheduled maintenance interval on the charcoal canister.



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Fig. Fig. 2: Evaporative emission canister used on the 1.8L engine-other models similar

Purge Control System

See Figures 3, 4, 5 and 6

The canister is connected to the engine via a purge control solenoid; a purge control valve is added to the system on turbo engines. The purge control solenoid is located as follows:



1.8L engine-on the firewall just to the right of the brake fluid reservoir.
 
1990-94 2.0L non-turbo engine-on the firewall, slightly right of center.
 
1990-94 2.0L turbo engine-the innermost solenoid in the solenoid cluster at the left rear corner of the engine compartment.
 
1995-98 2.0L non-turbo engine-mounted to the evaporative canister.
 
1995-98 2.0L turbo engines-on the firewall, to the left of the brake fluid reservoir.
 



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Fig. Fig. 3: Evaporative emission purge solenoid location-1.8L engine shown, early 2.0L non-turbo engines similar



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Fig. Fig. 4: Location of the evaporative emission purge solenoid-1990-94 2.0L turbo engine shown, later models similar



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Fig. Fig. 5: Evaporative emission purge and ventilation solenoid locations-1995-98 2.0L non-turbo engine



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Fig. Fig. 6: Location of the evaporative emission purge solenoid-2.4L engine

COMPONENT TESTING



Purge Control System Check
1990-94 NON-TURBO ENGINES
  1. Disconnect the red striped vacuum hose from the throttle body and connect it to a hand held vacuum pump.
  2.  
  3. Plug the open nipple on the throttle body.
  4.  
  5. Using the hand pump, apply vacuum while the engine is idling. Check that vacuum is maintained or released as outlined below:
    1. With the engine coolant at 140°F (60°C) or less-14.8 in. Hg of vacuum is maintained.
    2.  
    3. With the coolant at 158°F (70°C) or higher-14.8 in. Hg of vacuum is maintained.
    4.  

  6.  
  7. With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm within 3 minutes of starting vehicle. Try to apply vacuum using the hand held pump. Vacuum should leak.
  8.  
  9. With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm after 3 minutes have elapsed after starting vehicle. Apply 14.8 in. Hg of vacuum. The vacuum should be maintained momentarily, after which it should leak.
  10.  

The vacuum will leak continuously if the altitude is 7,200 ft. or higher, or the intake air temperature is 122°F (50°C) or higher.

  1. If the test results differ from the desired results, the purge control system is not operating properly.
  2.  

1990-92 TURBO ENGINES
  1. Disconnect the purge air hose from the intake hose and plug the air intake hose.
  2.  
  3. Connect a hand vacuum pump to the purge air hose.
  4.  
  5. Under various engine conditions, inspect the system operation:
    1. Allow the engine to cool to a temperature of 140°F (60°C) or below.
    2.  
    3. Start the engine and run at idle.
    4.  
    5. Using the hand pump, apply 14.8 in. Hg of vacuum. In this condition, the vacuum should be maintained.
    6.  
    7. Raise the engine speed to 3000 rpm.
    8.  
    9. Using the hand pump, apply 14.8 in. Hg of vacuum. In this condition, the vacuum should be maintained.
    10.  

  6.  
  7. Run the engine until the coolant temperature reaches 158°F (70°C). Inspect system operations as follows:
    1. Using the hand pump, apply 14.8 in. Hg of vacuum with the engine at idle. In this condition, vacuum should be maintained.
    2.  
    3. Increase the engine speed to 3000 rpm within 3 minutes of starting the engine. Try applying vacuum. The vacuum should leak.
    4.  
    5. After 3 minutes have elapsed after starting engine, raise the engine speed to 3000 rpm. Apply 14.8 in. Hg of vacuum. Vacuum should be maintained momentarily, after which it will leak.
    6.  

  8.  

The vacuum will leak continuously if the altitude is 7200 ft. or higher or the air temperature is 122°F (50°C) or higher.

  1. If the results of either test differs from specifications, the system is not functioning properly and will require further diagnosis.
  2.  

1993-94 TURBO ENGINES

See Figure 7

  1. Disconnect red striped vacuum hose from the throttle body and connect it to a hand-held vacuum pump.
  2.  



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Fig. Fig. 7: To test the purge control operation, connect the vacuum hose from the throttle body to a vacuum pump

  1. Plug nipple from which the vacuum hose was disconnected.
  2.  
  3. Allow the engine coolant to cool below 104°F (60°C) or below. Check system operation as follows:
    1. Start the engine and run at idle speed. Apply 14.8 in. Hg of vacuum. The vacuum should be maintained.
    2.  
    3. Run the engine at 3000 rpm. Apply 14.8 in. Hg of vacuum. The vacuum should be maintained.
    4.  

  4.  
  5. Run the engine until the coolant temperature reaches 158°F (70°C) of above. Inspect system operation as follows:
    1. With the engine at idle, apply 14.8 in. Hg of vacuum using the hand pump. The vacuum should be maintained.
    2.  
    3. Run the engine at 3000 rpm within 3 minutes after starting the engine, and try applying vacuum. The vacuum should leak.
    4.  
    5. Run the engine at 3000 rpm after 3 minutes have elapsed after starting the vehicle and apply 14.8 in Hg of vacuum. Vacuum will be maintained momentarily, then it will leak.
    6.  

  6.  

The vacuum will leak continuously if the altitude is 7200 ft. or higher or the air temperature is 122°F (50°C) or higher.

  1. If any of the test results differ from the specifications, there is a fault in the operation of the system and further diagnosis is required.
  2.  

1995-98 2.0L NON-TURBO ENGINES

See Figure 8

  1. Disconnect the vacuum hose from the throttle body, then connect it to a hand-held vacuum pump.
  2.  
  3. Plug the nipple where the vacuum hose was disconnected. Start the engine.
  4.  



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Fig. Fig. 8: Attach a hand-held vacuum pump to the vacuum hose-1995-98 2.0L non-turbo engine

  1. When the engine reaches operating temperature, coolant 176° F (80°C or higher), apply 15.7 in. Hg (53 kPa) of vacuum at idle to check the condition of the engine and vacuum as follows:
    1. Right after the engine is started, the vacuum should be maintained.
    2.  
    3. After ten or more seconds, the vacuum should leak.
    4.  

  2.  
  3. If any of the test results differ from the specifications, there is a fault in the operation of the system and further diagnosis is required.
  4.  

1995-98 2.0L TURBO AND 2.4L ENGINES

See Figure 9

This test requires the use of a special purge flow indicator tool, MB991700, or equivalent.

  1. Disconnect the purge hose form the EVAP canister, then connect Purge Flow Indicator MB991700, or equivalent between the canister and the purge hose.
  2.  
  3. The engine should be warmed up to operating temperature, 170-203°F. (80-95°C), with all lights, fans and accessories off. The transaxle should be in Park for automatics or Neutral for manuals.
  4.  



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Fig. Fig. 9: Purge control system check-1995-98 2.0L turbo engine shown, 2.4L similar

  1. Run the engine at idle for at least 3-4 minutes.
  2.  
  3. Check the purge flow volume when the brake is depressed suddenly a few times. The reading should be 2.5 SCFH (20cm/sec.)
  4.  
  5. If the volume is less than the standard value, check it again with the vacuum hose disconnected from the canister. If the purge flow volume is less than the standard, check for blockages in the vacuum port and vacuum hose, and also inspect the evaporative emission purge solenoid and purge control valve.
  6.  
  7. If the purge flow volume is at the standard value, replace the EVAP canister.
  8.  

Purge Control Valve
1990-94 2.0L TURBO ENGINE

See Figure 10

  1. The purge control valve is located to the right side of the battery. Remove the purge control valve from the engine compartment.
  2.  
  3. Connect a hand vacuum pump to the vacuum nipple of the purge control valve.
  4.  



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Fig. Fig. 10: Attach a hand vacuum pump to the nipple on the purge control valve

  1. Apply 15.7 in. Hg of vacuum and check air tightness. Blow in air lightly from the evaporative emission canister side nipple and check conditions as follows:

    If there is no vacuum applied to the valve-air will not pass.
     
    When 8.0 in. Hg of vacuum is applied to the valve-air will pass through.
     

  2.  
  3. Connect a hand vacuum pump to the positive pressure nipple of the purge control valve.
  4.  
  5. Apply a vacuum of 15.7 in. Hg and check for air tightness. The valve should be air tight.
  6.  
  7. If the results differ from the desired outcomes, replace the purge control valve.
  8.  

Evaporative Emission Purge Solenoid
1990-94 NON-TURBO AND 1993-94 TURBO ENGINES

See Figures 11, 12, 13 and 14

  1. Label and disconnect the 2 vacuum hoses from the purge control solenoid valve.
  2.  
  3. Disconnect the electrical harness connector from the solenoid.
  4.  
  5. Connect a hand vacuum pump to the nipple which the red striped vacuum hose was connected.
  6.  



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Fig. Fig. 11: Apply vacuum to the purge solenoid to check for air-tightness with and without voltage-1.8L engine



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Fig. Fig. 12: Using a hand-held vacuum gauge to check for air-tightness-1990-94 2.0L non-turbo and 1993-94 2.0L turbo engines

  1. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. The desired results are as follows:

    With battery voltage applied-vacuum should leak
     
    With battery voltage not applied-vacuum should be maintained
     

  2.  
  3. Measure the resistance across the terminals of the solenoid. The desired reading is 36-44 ohms when at 68°F (20°C).
  4.  



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Fig. Fig. 13: Battery voltage applied to the terminals of the evaporative emission purge solenoid



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Fig. Fig. 14: Measuring the resistance between the terminals of the evaporative emission purge solenoid

  1. If any of the test results differ from the desired outcomes, replace the purge control solenoid.
  2.  

1990-92 2.0L TURBO ENGINE
  1. Label and disconnect the 2 vacuum hoses from the purge control solenoid valve.
  2.  
  3. Disconnect the electrical harness connector from the solenoid.
  4.  
  5. Connect a hand vacuum pump to the nipple which the red striped vacuum hose was connected.
  6.  
  7. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. With battery voltage applied, vacuum should be maintained. Without voltage, vacuum should leak
  8.  
  9. Measure the resistance across the terminals of the solenoid. The desired reading is 36-44 ohms when at 68°F (20°C).
  10.  
  11. If any of the test results differ from the specifications, replace the emission purge control solenoid.
  12.  

1995-98 VEHICLES

See Figures 15, 16, 17 and 18

  1. Tag and disconnect the vacuum hoses from the solenoid valve.
  2.  
  3. Detach the harness connector.
  4.  
  5. Attach a hand-held vacuum pump to the nipple (A) of the solenoid valve, as shown in the accompanying figures.
  6.  



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Fig. Fig. 15: Evaporative emission purge solenoid vacuum check-1995-98 2.0L non-turbo engine



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Fig. Fig. 16: Purge solenoid valve test connections-1995-98 2.0L turbo engine



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Fig. Fig. 17: Test connections for the evaporative purge solenoid-2.4L engine

  1. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. The desired results are as follows:

    With battery voltage applied-vacuum should be maintained
     
    With battery voltage not applied-vacuum should leak
     

  2.  
  3. Measure the resistance across the terminals of the solenoid. The standard values are as follows:
  4.  



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Fig. Fig. 18: Measure the resistance across the terminal of the solenoid valve-2.4L engine shown, others similar

    1. 2.0L non-turbo engines: 25-35 ohms when at 68-20-
    2.  
    3. 2.0L turbo and 2.4L engines: 34-44 ohms when at 68-20-
    4.  


  1. If any of the test results differ from the specifications, replace the emission purge control solenoid.
  2.  

Evaporative Canister

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. If necessary, raise and safely support the vehicle, remove the front passengers side wheel, then remove the splash shield.
  4.  
  5. If necessary, remove the battery from the vehicle.
  6.  
  7. Tag and disconnect all necessary vacuum lines.
  8.  
  9. Unfasten and retaining bolts and/or straps, then remove the canister from the vehicle
  10.  
  11. Installation is the reverse of the removal procedure.
  12.  

Solenoid Valves
  1. Disconnect the negative battery cable.
  2.  
  3. Label and remove the vacuum and electrical harness connections from the purge control solenoid.
  4.  
  5. Remove the solenoid and mounting bracket from the engine compartment.
  6.  
  7. Installation is the reverse of the removal procedure.
  8.  

 
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