GM Lumina/Grand Prix/Cutlass Supreme/Regal 1988-1996

Air Injection Reaction (AIR) System

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OPERATION



The Air Injection Reaction (AIR) system is used to reduce carbon monoxide (CO), hydrocarbon (HC) and oxides of nitrogen (NOx) emissions. The system also heats up the catalytic converter on engine start-up so the exhaust gases will be converted more quickly. This system is only utilized on 6-cylinder engines with manual transaxles.

The system consists of the following components.

Air Pump

An air pump may be either belt driven OFF the crankshaft (2.8L and 3.1L engines) or electric and accessed from under the vehicle, after the right front inner fender splash shield is removed (3.4L engine). The air pump supplies air to the AIR system.

Control Valve

Air flows through the pump through an ECM controlled valve (called a control valve) through a check valve to the exhaust ports or to the atmosphere.

Check Valve

The check valve prevents back flow of exhaust into the pump in the event of an exhaust backfire.

AIR System Control Valve
2.8L AND 3.1L ENGINES

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Cross-sectional view of the Electric Air Control (EAC) valve

The Electric Air Control (EAC) valve combines electronic control with the normal diverter valve function. This valve can be electronically controlled to provide divert air under any driving mode.

When the solenoid is de-energized, the pressurized air from the air pump is allowed to enter the decel timing chamber. This places sufficient pressure on the metering valve diaphragm to overcome spring tension, closing the valve, causing air to divert to the atmosphere (silencer).

At higher engine speeds, excess air is exhausted to the atmosphere (silencer) through the pressure relief valve.

Pulsair Shut-off Valve
3.4L ENGINES

See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: Cross-sectional view of the electric pulsair shut- OFF valve

A pulsair air management system makes the use of the vacuum peaks naturally occurring at the exhaust ports. This vacuum draws air through the shut- OFF valve through a one-way valve, and into the exhaust ports.

A pulseair shut- OFF valve shuts OFF air to the pulsair system when the ECM decides air is not desirable, such as during deceleration. When the solenoid is energized, intake manifold vacuum is applied to the bottom of the diaphragm and pulls the valve open against spring tension, allowing air to flow from the clean side of the air cleaner to the exhaust ports.

When the ECM de-energizes the solenoid, no vacuum can be applied to the diaphragm, and spring tension forces the valve closed.

INSPECTION



Air Pump
  1. Check the pump for a seized condition.
  2.  
  3. Check hoses, tubes, and connections for leaks and proper routing.
  4.  
  5. Check for air flow from the control/divert valve.
  6.  
  7. Check the pump for proper mounting.
  8.  
  9. If no irregularities exist and the pump is noisy, replace the pump assembly.
  10.  

Do not attempt to lubricate the pump.

Hoses and Pipes
  1. Check the hoses or or pipes for deterioration or holes.
  2.  
  3. Inspect all hoses for pipe connections, and clamp tightness.
  4.  
  5. Check hose and pipe routing. Interference may cause wear.
  6.  
  7. If a leak is suspected on the pressure side of the system, or if a hose or pipe has been disconnected on the pressure side, the connections should be checked for leaks with a soapy water solution. With the air pump running, bubbles will form if a leak exists.
  8.  

Check Valve
  1. A check valve should be inspected whenever the hose is disconnected from a check valve or whenever check valve failure is suspected.
  2.  
  3. Blow through the check valve (toward the exhaust manifold) then, attempt to suck back through the check valve. Flow should only be in one direction (toward the manifold). Replace a valve which does not operate properly
  4.  

COMPONENT TESTING



See Figures 3, 4 and 5

Click image to see an enlarged view

Fig. Fig. 3: AIR system testing-2.8L and 3.1L engines



Click image to see an enlarged view

Fig. Fig. 4: AIR system testing-3.4L engines



Click image to see an enlarged view

Fig. Fig. 5: AIR system testing-3.4L engines

Please refer to the accompanying charts for AIR system testing.

REMOVAL & INSTALLATION



Air Pump
2.8L AND 3.1L ENGINES

See Figure 6

Click image to see an enlarged view

Fig. Fig. 6: Air pump mounting-2.8L and 3.1L engines

  1. Disconnect the negative battery cable.
  2.  
  3. Hold the pump pulley from turning by compressing the drive belt, then loosen the pump pulley bolts.
  4.  
  5. Loosen the pump mounting bracket bolts and release the tension from the belt.
  6.  
  7. Move the belt out of the way.
  8.  
  9. Remove the hoses, vacuum and electrical connections from the pump.
  10.  
  11. Remove the pulley from the pump.
  12.  
  13. If required, insert needle nose pliers and pull the filter fan from the hub.
  14.  

To install:
  1. Install the air pump to the mounting brackets, then tighten the bolts to the specifications shown in the accompanying illustration.
  2.  
  3. Attach the hoses, vacuum and electrical connections to the pump.
  4.  
  5. Install the control valve.
  6.  
  7. Install a new filter fan onto the pump hub.
  8.  
  9. Install the spacer and pump pulley against the centrifugal filter fan.
  10.  
  11. Tighten the pulley bolts to 10 ft. lbs. (13 Nm).
  12.  

The preceding procedure will compress the centrifugal filter fan onto the pump hole. Do NOT drive the filter fan on with a hammer. There might be a slight amount of interference with the housing bore, this is normal. After the new filter has been installed, it may squeal upon initial operation until the outside diameter sealing lip has worn in. This may require a short period of pump operation at various engine speeds.

  1. Install the pump drive belt and adjust.
  2.  
  3. Connect the negative battery cable, then start the engine and check for air injection system operation.
  4.  

3.4L ENGINE
See Figure 7


Click image to see an enlarged view

Fig. Fig. 7: Electric AIR pump and related components-3.4L engine

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the vehicle. Remove the right front wheel and tire assembly.
  4.  
  5. Unfasten the 3 right side inner fender splash shield retaining bolts/screws. Remove the 2 inner fender support bracket bolts/screws.
  6.  
  7. Disconnect the air outlet hose from the electric air pump.
  8.  
  9. Detach the vacuum hose from the electric pulsair shut- OFF valve.
  10.  
  11. Remove the 3 air pump retaining bolts/screws.
  12.  
  13. Carefully lower the air pump assembly, then detach the 4-pin harness connector and the wiring harness clip.
  14.  
  15. Remove the electric air pump assembly.
  16.  
  17. Unfasten the electric pulsair shut- OFF valve bolt/screw from the pump bracket.
  18.  
  19. Detach the inlet hose and the 2-pin wire harness connector from the pulsair shut- OFF valve.
  20.  
  21. Remove the electric pulsair shut- OFF valve from the bracket.
  22.  

To install:
  1. Fasten the pulsair shut- OFF valve bolt/screw to the air pump bracket.
  2.  
  3. Attach the inlet hose and 2-pin wire harness connector to the pulsair shut- OFF valve.
  4.  
  5. Position the electric air pump assembly in the upper right front fender well while attaching the 4-pin harness connector.
  6.  
  7. Install the 3 air pump retaining bolts/screws.
  8.  
  9. Fasten the 4-pin harness connector body clip.
  10.  
  11. Attach the air outlet hose and vacuum hose.
  12.  
  13. Install the 2 inner fender support bracket bolts/screws and the 3 right side inner fender splash shield bolts/screws.
  14.  
  15. Install the right front wheel and tire assembly, then carefully lower the vehicle.
  16.  
  17. Connect the negative battery cable, then start the engine and check for proper system operation.
  18.  

AIR System Check Valve

See Figures 8 and 9

  1. Disconnect the negative battery cable.
  2.  

The 2.8L and 3.1L engines use one check valve. The 3.4L engine may utilize two check valves; one on the right side and one on the left.

  1. Remove any engine components necessary for access to the right or left side check valve, as applicable.
  2.  
  3. Unfasten the clamp, then disconnect the air hose from the check valve(s).
  4.  
  5. Unscrew the check valve from the air injection pipe.
  6.  

To install:
  1. Screw the check valve onto the air injection pipe.
  2.  
  3. Connect the air hose to the check valve(s) and secure with the clamp.
  4.  
  5. Install any components removed for access to the check valve(s).
  6.  
  7. Connect the negative battery cable.
  8.  



Click image to see an enlarged view

Fig. Fig. 8: Control valve and related components-3.1L engine shown



Click image to see an enlarged view

Fig. Fig. 9: AIR check valve mounting-3.4L engine shown

 
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