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    Ford Crown Victoria/Grand Marquis 1989-1998

    Thermactor Air Injection System

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    OPERATION



    The thermactor air injection system reduces the hydrocarbon and carbon monoxide content of the exhaust gases by continuing the combustion of unburned gases after they leave the combustion chamber. This is done by injecting fresh air into the hot exhaust stream leaving the exhaust ports or into the catalyst. At this point, the fresh air mixes with hot exhaust gases to promote further oxidation of both the hydrocarbons and carbon monoxide, thereby reducing their concentration and converting some of them into harmless carbon dioxide and water.

    All vehicles with 5.0L and 5.8L engines are equipped with a managed air thermactor system. This system is utilized in electronic control systems to divert thermactor air either upstream to the exhaust manifold check valve or downstream to the rear section check valve and dual bed catalyst. The system will also dump thermactor air to atmosphere during some operating modes.

    The thermactor air injection system consists of the air supply pump, air bypass valve, check valves, air supply control valve, combination air bypass/air control valve, solenoid vacuum valve, thermactor idle vacuum valve and vacuum control valve. Components will vary according to year and application.

    See Figures 1 and 2

    Click image to see an enlarged view

    Fig. Fig. 1: Managed air thermactor system functional schematic



    Click image to see an enlarged view

    Fig. Fig. 2: Thermactor system component locations-1990-91 5.0L engine

    Air Supply Pump

    The air supply pump is a belt-driven, positive displacement, vane-type pump that provides air for the thermactor system. It is available in 19 and 22 cu. in. sizes, either of which may be driven with different pulley ratios for different applications. The pump receives air from a remote silencer filter on the rear side of the engine air cleaner attached to the pump's air inlet nipple or through an impeller-type centrifugal filter fan.

    See Figure 3

    Click image to see an enlarged view

    Fig. Fig. 3: Thermactor air supply pump

    Air Bypass Valve

    The air bypass valve supplies air to the exhaust system with medium and high applied vacuum signals when the engine is at normal operating temperature. With low or no vacuum applied, the pumped air is dumped through the silencer ports of the valve or through the dump port.

    See Figure 4

    Click image to see an enlarged view

    Fig. Fig. 4: Air bypass valve types

    Air Check Valve

    The air check valve is a 1-way valve that allows thermactor air to pass into the exhaust system while preventing exhaust gases from passing in the opposite direction.

    See Figure 5

    Click image to see an enlarged view

    Fig. Fig. 5: Air check valve

    Air Supply Control Valve

    The air supply control valve directs air pump output to the exhaust manifold or downstream to the catalyst system depending upon the engine control strategy. It may also be used to dump air to the air cleaner or dump silencer.

    Combination Air Bypass/Air Control Valve

    The combination air control/bypass valve combines the secondary air bypass and air control functions. The valve is located in the air supply line between the air pump and the upstream/downstream air supply check valves.

    The air bypass portion controls the flow of thermactor air to the exhaust system or allows thermactor air to be bypassed to atmosphere. When air is not being bypassed, the air control portion of the valve switches the air injection point to either an upstream or downstream location.

    Solenoid Vacuum Valve

    The normally closed solenoid valve assembly consists of 2 vacuum ports with an atmospheric vent. The valve assembly can be with or without control bleed. The outlet port of the valve is opened to atmospheric vent and closed to the inlet port when de-energized. When energized, the outlet port is opened to the inlet port and closed to atmospheric vent. The control bleed is provided to prevent contamination entering the solenoid valve assembly from the intake manifold.

    Thermactor Idle Vacuum Valve

    The Thermactor Idle Vacuum (TIV) valve vents the vacuum signal to atmosphere when the preset manifold vacuum or pressure is exceeded. It is used to divert thermactor airflow during cold starts to control exhaust backfire.

    Vacuum Control Valve

    The Vacuum Control Valve (VCV) controls vacuum to other emission devices during engine warm-up. The 2-port VCV opens when engine coolant reaches a pre-determined calibration temperature. The 4-port VCV functions in the same manner, as it is nothing more than two 2-port VCVs in one housing. The 3-port VCV switches the vacuum source to the center port from the top or bottom ports. Electrical switches can be either open or closed until the VCV is fully cycled. The VCV responds to a sensing bulb immersed in engine coolant by utilizing a wax pellet principle.

    Vacuum Check Valve

    The vacuum check valve blocks airflow in one direction, allowing free airflow in the other direction. The check valve side of the valve will hold the highest vacuum seen on the vacuum side.

    TESTING



    Air Supply Pump
    1. Check belt tension and adjust if needed.
    2.  


    WARNING
    Do not pry on the pump to adjust the belt. The aluminum housing is likely to collapse.

    1. Disconnect the air supply hose from the bypass control valve.
    2.  
    3. The pump is operating properly if airflow is felt at the pump outlet and the flow increases as engine speed increases.
    4.  
    5. If the pump is not operating as described in Step 3 and the system is equipped with a silencer/filter, check the silencer/filter for possible obstruction before replacing the pump.
    6.  

    Air Bypass Valve

    1. Turn the ignition key OFF .
    2.  
    3. Remove the control vacuum line from the bypass valve.
    4.  
    5. Start the engine and bring to normal operating temperature.
    6.  
    7. Check for vacuum at the vacuum line. If there is no vacuum, check the solenoid vacuum valve assembly. If vacuum is present, inspect the air bypass valve.
    8.  
    9. Turn the engine OFF and disconnect the air hose at the bypass valve outlet.
    10.  
    11. Inspect the outlet for damage from the hot exhaust gas.
    12.  
    13. If the valve is damaged, replace it. If the valve is not damaged, check the bypass valve diaphragm.
    14.  
    15. Connect a vacuum pump to the bypass valve and apply 10 in. Hg of vacuum.
    16.  
    17. If the valve holds vacuum, leave the vacuum applied and go to Step 10. If the valve does not hold vacuum, it must be replaced.
    18.  
    19. Start the engine and increase the engine speed to 1500 rpm.
    20.  
    21. Check for air flow at the valve outlet, either audibly or by feel. If there is air flow, go to Step 12. If there is no air flow, replace the air bypass valve.
    22.  
    23. Release the vacuum applied by the vacuum pump and check that the air flow switches from the valve outlet to the dump port or silencer ports, either audibly or by feel.
    24.  
    25. If the air flow does not switch, replace the air bypass valve. If the air flow switches, the air bypass valve is okay, check the air supply control valve, or check the air check valve.
    26.  

    Air Check Valve

    1. Turn the ignition OFF .
    2.  
    3. Visually inspect the thermactor system hoses, tubes, control valve(s) and check valve(s) for leaks or external signs of damage, from the back flow of hot exhaust gases.
    4.  
    5. If the hoses and valves are okay, go to Step 4. If they are not, service or replace the damaged parts, including the check valve.
    6.  
    7. Remove the hose from the check valve inlet and visually check the inside of the hose for damage from hot exhaust gas.
    8.  
    9. If the hose is clean and undamaged, go to Step 6. If not, replace the hose and check valve.
    10.  
    11. Start the engine and listen for escaping exhaust gas from the check valve. Feel for the gas only if the engine temperature is at an acceptable level.
    12.  
    13. If any exhaust gas is escaping, replace the check valve.
    14.  

    Air Supply Control Valve

    1. Turn the ignition OFF .
    2.  
    3. Remove the hoses from the air control valve outlets and inspect the outlets for damage from hot exhaust gases.
    4.  
    5. If the air supply control valve is damaged, it must be replaced, then check the air check valve. If the air supply control valve is not damaged, go to Step 4.
    6.  
    7. Remove the vacuum line from the air supply control valve. Start the engine and bring to normal operating temperature, then shut the engine OFF .
    8.  
    9. Restart the engine and immediately check for vacuum at the hose. If vacuum was present at the start, go to Step 6. If vacuum was not present at the start, check the solenoid vacuum valve.
    10.  
    11. Start the engine and let it run. Check for the vacuum to change from high to low.
    12.  
    13. If the vacuum dropped to 0 within a few minutes after the engine started, go to Step 8. If not, check the solenoid vacuum valve.
    14.  
    15. Connect a vacuum pump to the air supply control valve and apply 10 in. Hg of vacuum.
    16.  
    17. If the valve holds vacuum, go to Step 10. If it does not hold vacuum, replace the air supply control valve.
    18.  
    19. Start the engine and bring to normal operating temperature. Make sure air is being supplied to the air supply control valve.
    20.  
    21. If air is present, go to Step 12. If air is not present, check air pump operation.
    22.  
    23. Leave the engine running and apply 10 in. Hg of vacuum to the air supply control valve. Increase engine speed to 1500 rpm.
    24.  
    25. If air flow comes out of outlet A, go to Step 14. If not, replace the air supply control valve.
    26.  
    27. Leave the engine running. Vent the vacuum pump until there is 0 vacuum.
    28.  
    29. If the air flow switches from outlet A to outlet B, the air supply control valve is okay. If the air flow does not switch, replace the air supply control valve.
    30.  

    See Figure 6

    Click image to see an enlarged view

    Fig. Fig. 6: Air supply control valve types

    Combination Air Bypass/Air Control Valve

    1. Turn the ignition OFF .
    2.  
    3. Remove the hoses from the combination air control valve outlets A and B and inspect the outlets for damage from hot exhaust gases.
    4.  
    5. If the valve appears damaged, replace it, then check the air check valve. If the valve is not damaged, go to Step 4.
    6.  
    7. Leave the hoses disconnected from the valve. Disconnect and plug the vacuum line to port D.
    8.  
    9. Start the engine and run at 1500 rpm. If air flow is present at the valve, go to Step 6. If it is not, check the air pump. If the air pump is okay, replace the combination air control valve.
    10.  
    11. Leave the engine running. Disconnect both vacuum lines from ports D and S.
    12.  
    13. Measure the manifold vacuum at both ports. If the proper vacuum is present, go to Step 8. If not, check the solenoid vacuum valve.
    14.  
    15. Turn the ignition OFF . Reconnect the vacuum line to port D but leave the vacuum line to port S disconnected and plugged.
    16.  
    17. Start the engine and run it at 1500 rpm. If air flow is present at outlet B but not at outlet A, go to Step 10. If not, replace the combination air control valve and reconnect all hoses.
    18.  
    19. Turn the ignition OFF and leave the vacuum line to port S disconnected and unplugged.
    20.  
    21. Apply 8-10 in. Hg of vacuum to port S on the combination valve. Start the engine and run at 1500 rpm. If air flow is present at outlet A, the combination valve is okay. If not, replace the combination air control valve.
    22.  

    If the combination valve is a bleed type, this will affect the amount of air flow.

    See Figure 7

    Click image to see an enlarged view

    Fig. Fig. 7: Combination air bypass/air control valve

    Solenoid Vacuum Valve

    1. The ports should flow air when the solenoid is energized.
    2.  
    3. Check the resistance at the solenoid terminals with an ohmmeter. The resistance should be 51-108 ohms.
    4.  
    5. If the resistance is not as specified, replace the solenoid.
    6.  

    The valve can be expected to have a very small leakage rate when energized or de-energized. This leakage is not measurable in the field and is not detrimental to valve function.

    See Figure 8

    Click image to see an enlarged view

    Fig. Fig. 8: Solenoid vacuum valve

    TIV Valve

    The following tests apply to valves with the words ASH or RED on the decal.

    1. Start the engine and let it idle. Apply the parking brake, block the drive wheels and place the transmission in N .
    2.  
    3. Apply vacuum to the small nipple and place your fingers over the TIV valve atmospheric vent holes. If no vacuum is sensed, the TIV valve is damaged and must be replaced.
    4.  
    5. With the engine still idling in N , use a suitable vacuum source to apply 1.5-3.0 in. Hg vacuum to the ASH TIV valve large nipple, or 3.5-4.5 in. Hg vacuum to the RED TIV valve large nipple. If vacuum is still sensed when placing your fingers over the vent holes, the TIV valve is damaged and must be replaced.
    6.  

    See Figure 9

    Click image to see an enlarged view

    Fig. Fig. 9: TIV valve

    Vacuum Control Valve

    1. When the engine is cold, passage A to B should be closed and passage A to C should be open.
    2.  
    3. When the engine is at normal operating temperature, the valve should be open between A and B and closed between A and C.
    4.  

    On 4-port valves, check A1to B1and A2to B2separately.

    1. If the valve does not operate as specified in Steps 2 and 3, it must be replaced.
    2.  

    See Figure 10

    Click image to see an enlarged view

    Fig. Fig. 10: Vacuum control valve types

    Vacuum Check Valve

    1. Apply 16 in. Hg vacuum to the "check" side of the valve and trap.
    2.  
    3. If vacuum remains above 15 in. Hg for 10 seconds, the valve is okay. If not, the valve must be replaced.
    4.  

    See Figure 11

    Click image to see an enlarged view

    Fig. Fig. 11: Vacuum check valve

    REMOVAL & INSTALLATION



    Air Supply Pump
    1. Disconnect the negative battery cable.
    2.  
    3. Remove the drive belt from the air pump pulley.
    4.  
    5. Label and disconnect the air hose(s) from the air pump.
    6.  
    7. Remove the mounting bolts and, if necessary, the mounting brackets.
    8.  
    9. Remove the air pump from the vehicle.
    10.  
    11. Installation is the reverse of the removal procedure. Adjust the drive belt tension as explained in General Information & Maintenance .
    12.  

    Air Bypass Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Label and disconnect the air inlet and outlet hoses and the vacuum hose from the bypass valve.
    4.  
    5. Remove the bypass valve from the vehicle.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    Air Check Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Disconnect the input hose from the check valve.
    4.  
    5. Remove the check valve from the connecting tube.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    Air Supply Control Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Label and disconnect the air hoses and the vacuum line from the air control valve.
    4.  
    5. Remove the air control valve from the vehicle.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    Combination Air Bypass/Air Control Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Label and disconnect the air hoses and vacuum lines from the valve.
    4.  
    5. Remove the valve from the vehicle.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    Solenoid Vacuum Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Detach the electrical connector from the solenoid valve. Label and disconnect the vacuum lines.
    4.  
    5. Remove the mounting bolts and remove the solenoid valve.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    TIV Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Label and disconnect the vacuum lines from the valve.
    4.  
    5. Remove the valve from the vehicle.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

    Vacuum Control Valve

    1. Disconnect the negative battery cable.
    2.  
    3. Drain the cooling system, as necessary.
    4.  


    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. Label and disconnect the vacuum lines from the valve.
    2.  
    3. Remove the valve.
    4.  
    5. Installation is the reverse of the removal procedure. Fill the cooling system as explained in General Information & Maintenance .
    6.  

     
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