Manifold Air Intake Control System (Taurus 1 and 2)

General description

1. The Manifold Air Control System (see figure) reduces the carbon monoxide and hydrocarbon content in the exhaust gases by injecting fresh air into the hot exhaust gas leaving the tailpipe.



When fresh air mixes with hot exhaust gas, oxidation increases, reducing the concentration of hydrocarbons and carbon monoxide, which are converted into harmless carbon dioxide and water.

2. All 3.8LV6 engine vehicles use a Manifold Air Intake Control System (MAIS) which directs air flow either upward to the exhaust manifold check valve or downward to the lower section check valve and dual stage catalytic converter.

3. The air control valve is used to direct the air flow up or down. The air flow valve releases the air into the atmosphere. These two valves are combined into one unit in the 3.8LV6 engine (see figure).



4. Early four-cylinder engines are equipped with an injection system called an air pulsator or intake system - II (see figure). This design uses the natural pulsation of air that occurs in the exhaust system to force air into the exhaust manifold and catalytic converter through air pulsation valves.

Examination

Air pump

5. Check and adjust the drive belt tension (see chapter 1).

6. Disconnect the air supply hose from the inlet of the air bypass valve.

7. The pump is then working satisfactorily when an air flow is felt at its outlet with the engine idling, this flow increases as the engine speed increases.

8. If the pump does not meet the above conditions, replace it with a new one or disassemble the unit.

Combination of air flow valves/and air flow control

9. Mark and disconnect the hoses from the outlets of these valve combinations (see figure).



10. Disconnect the vacuum hose from the combination valve and insert a plug into it.

11. With the engine speed at 1500 rpm, make sure that air comes out of the ventilation holes.



12. Pull out and disconnect the vacuum hose from the "O" outlet, then disconnect and insert the plug into the "S" outlet hose.

13. Immediately disconnect the hose leading to outlet "D" and make sure that there is a vacuum in it.

14. Connect the hose to outlet D.

15. With the engine speed at 1500 rpm, make sure that air comes out of hole "B" and there is no air flow in hole "A".

16. Connect a piece of hose to the "S" outlet.

17. With the engine running at 1500 rpm, apply vacuum to this hose and then make sure that air comes out of outlet "A".

18. Reconnect all hoses. Remember to remove the plug from the "S" outlet hose before reconnecting it.

19. If all the above conditions do not match, replace the combination valve with a new one.

Check valve

20. Disconnect the hoses from both ends of the check valve.

21. Blow through the valves through both ends, making sure that air only flows in one direction.

22. If air flows in both directions or does not flow at all, replace the check valve with a new one.

23.. When connecting the valve, remember that it must be installed in a certain direction.

Noise test of the air intake system into the exhaust manifold

24. When inlet to the manifold under normal conditions, the pitch of the noise increases with increasing engine speed. To determine whether this noise is the result of a faulty injection system, disconnect the drive belt (making sure its tension is normal) and inspect the engine. If the noise disappears, proceed to the diagnostics below.

Caution: The check will be worthwhile if the pump has been driven for at least 500 miles (i.e. miles of the vehicle's mileage). Reinstall the drive belt (chapter 1).

25. If the belt produces significant noise:

a) check the belt tension (see chapter 1);

b) check the pump, replace if necessary;

v) the pulley mount may be loose. Tighten the mounting bolts as required;

g) the support brackets or bolts may be loose, broken, or missing. Tighten or replace if necessary.

26. If you hear loud mechanical noise:

a) perhaps there is a mounting bolt that is too tight;

b) the drive belt is too tight (see chapter 1);

v) the air pump adjustment lever is faulty, remove it if necessary;

g) if the adjusting lever is worn out, replace it.

27. If you hear intense noise from the air intake system in the exhaust manifold (whistling or buzzing sounds):

a) check for possible leaks in the hoses;

b) the hose may be loose, punctured or kinked - correct or replace the hose and/or clamps as required;

v) check if any of the hoses are touching other parts of the engine and adjust or reposition the hose to prevent further contact;

g) the air bypass valve may be out of order (see paragraph 9) replace it if necessary;

d) check the functionality of the check valve (see paragraph 20), replace if necessary;

e) check and tighten loose pump or pulley fasteners;

and) check the pump outlet tip - it should be rigid and not bent. Inspect the tip and clear the air passage of all foreign material. Replace a bent tip;

c) check for air bleed through the bypass valve (idle only). On many vehicles, the air intake system into the exhaust manifold was designed to bleed air at idle and thus prevent the catalytic converter from overheating. This condition is normal. Before going further, determine that the noise stabilizes at higher RPMs;



and) check the air release through the air bypass valve (release at slow and idle speed).

On many vehicles, air from the intake system is discharged into an air cleaner or a separate muffler. Make sure the hoses are intact and connected correctly.

28. If you hear a loud noise from the pump, make sure the pump has been broken in sufficiently (at least 500 miles). Check for possible wear and damage to the pump and replace if necessary.

Replacement of elements

29. To replace the components of the air flow valve, the air leakage control valve, the check valve, the combined air flow control valve or the silencer, first mark them, then disconnect the hoses leading to them, replace the faulty components, then reconnect the hoses to the appropriate outlets. The hoses must be in good condition, otherwise they must be replaced with new ones.

30. To replace the air pump, first loosen the corresponding engine drive belts (see chapter 1), then remove the faulty pump from the support bracket. Label all wires and hoses as you remove them.

31. When replacing check valves on the air pulse system (intake system II), use a check valve wrench.

32. After installing the new pump, adjust the belt tension (see chapter 1).