GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Air Management System

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The AIR management system, is used to provide additional oxygen to continue the combustion process after the exhaust gases leave the combustion chamber. Air is injected into either the exhaust port(s), the exhaust manifold(s) or the catalytic converter by an engine driven air pump. The system is in operation at all times and will bypass air only momentarily during deceleration and at high speeds. The bypass function is performed by the AIR Management Valve, while the check valve protects the air pump by preventing any backflow of exhaust gases.

The AIR management system helps reduce HC and CO content in the exhaust gases by injecting air into the exhaust ports during cold engine operation. This air injection also helps the catalytic converter to reach the proper temperature quicker during warm-up. When the engine is warm (Closed Loop), the AIR system injects air into the beds of a three-way converter to lower the HC and the CO content in the exhaust.

The Air Management system utilizes the following components:



An engine driven AIR pump
 
AIR management valves (Air Control, Air Switching)
 
Air flow and control hoses
 
Check valves
 
A dual-bed, three-way catalytic converter
 

The belt driven, vane-type air pump is located at the front of the engine and supplies clean air to the AIR system for purposes already stated. When the engine is cold, the Electronic Control Module (ECM) energizes an AIR control solenoid. This allows air to flow to the AIR switching valve. The AIR switching valve is then energized to direct air to the exhaust ports.

When the engine is warm, the ECM/PCM de-energizes the AIR switching valve, thus directing the air between the beds of the catalytic converter. This provides additional oxygen for the oxidizing catalyst in the second bed to decrease HC and CO, while at the same time keeping oxygen levels low in the first bed, enabling the reducing catalyst to effectively decrease the levels of NOx.

If the AIR control valve detects a rapid increase in manifold vacuum (deceleration), certain operating modes (wide open throttle, etc.) or if the ECM/PCM self-diagnostic system detects any problem in the system, air is diverted to the air cleaner or directly into the atmosphere.

The primary purpose of the ECM/PCM's divert mode is to prevent backfiring. Throttle closure at the beginning of deceleration will temporarily create air/fuel mixtures which are too rich to burn completely. These mixtures become burnable when they reach the exhaust if combined with the injection air. The next firing of the engine will ignite this mixture causing an exhaust backfire. Momentary diverting of the injection air from the exhaust prevents this.

The AIR management system check valves and hoses should be checked periodically for any leaks, cracks or deterioration.

REMOVAL & INSTALLATION



Air Pump

See Figures 1 and 2

  1. Remove the AIR management valves and/or adapter at the pump.
  2.  
  3. Loosen the air pump adjustment bolt and remove the drive belt.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Loosen the air pump adjustment bolt ...



Click image to see an enlarged view

Fig. Fig. 2: ... then remove the drive belt

  1. Remove the pump pulley.
  2.  
  3. Unscrew the pump mounting bolts and then remove the pump.
  4.  

To install:
  1. Install the pump with the mounting bolts loose.
  2.  
  3. Attach the pump pulley to the pump.
  4.  
  5. Install the pump belt, then adjust.
  6.  
  7. Install the AIR management valves and/or adapter at the pump.
  8.  
  9. Tighten the mounting bolts to 20-35 ft. lbs. (27-56 Nm).
  10.  

Check Valve
  1. Release the clamp and disconnect the air hoses from the valve.
  2.  
  3. Unscrew the check valve from the air injection pipe.
  4.  

To install:
  1. Install the check valve into the air injection pipe.
  2.  
  3. Connect the hoses and tighten with the clamps.
  4.  

Air Management Valve
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Tag and disconnect the vacuum hose from the valve.
  6.  
  7. Tag and disconnect the air outlet hoses from the valve.
  8.  
  9. Bend back the lock tabs and then remove the bolts holding the elbow to the valve.
  10.  
  11. Tag and disconnect any electrical connections at the valve and then remove the valve from the elbow.
  12.  

To install:
  1. Install the valve to the bracket or adapter and lock tabs if used, with a new gasket.
  2.  
  3. Tighten the attaching screws to 140 inch lbs. (16 Nm).
  4.  
  5. Bend the tab to hex flat against the bolt and screw heads.
  6.  
  7. Install the outlet and vacuum signal hoses and electrical connections, then check for leaks and correct operation.
  8.  

 
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