GM Corvette 1984-1996 Repair Guide

Air Injection (AIR) System

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OPERATION



The Air Injection Reaction (AIR) system, also called the Secondary Air Injection (AIR) system on later model vehicles, helps reduce Hydrocarbon (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NO x ) exhaust emissions. It also causes the oxidation catalytic converter to heat quickly which allows the conversion of exhaust gases to occur sooner.

The AIR pump is mounted to either the front of the engine or located in the left front corner of the engine compartment and supplies the air for the system. The electric air pump pressurizes air from the air cleaner and pumps it to the check valves located near the exhaust manifolds. By providing the ground, the PCM completes the circuit which energizes the pump relay and turns both the pump and the integral stop valve on. When the PCM turns the pump off, it also de-energizes the integral stop valve solenoid so no air is directed into the exhaust ports.

Anytime the engine coolant temperature is above 59°F (15°C) after startup, the PCM will enable this system and operate it for a maximum of about 3 to 4 minutes or until the system enters "Closed Loop". The following are some of the conditions which will cause the PCM to disable the system:



When engine rpm is below 400 rpm
 
Under heavy acceleration
 
The catalytic converter is overheating
 
Engine coolant temperature is less than 59°F (15°C)
 
Fuel control is not within normal ranges
 
Engine rpm is above 2825 rpm (5.7L) or 3200 rpm (3.4L) for more than 5 seconds
 
When the PCM detects a problem in the system and sets a diagnostic trouble code (DTC)
 

SERVICE



AIR Pump
  1. Inspect the hoses, tubes and all connections for possible leaks and proper routing.
  2.  
  3. Check for air flow to the exhaust ports.
  4.  
  5. Check the pump for proper mounting.
  6.  

Hoses and Pipes
  1. Check for deterioration or holes in the hoses and pipes.
  2.  
  3. Make sure all connections and clamps are tight.
  4.  
  5. Check for proper routing as interference may cause premature wear.
  6.  

Check Valve
  1. Blow through the check valve towards the cylinder head, then attempt to suck back through the valve (or blow through the other side).
  2.  
  3. Flow should only be in one direction (towards the exhaust manifold). Replace as necessary.
  4.  

REMOVAL & INSTALLATION




CAUTION
Make sure the engine is cool before attempting to service the secondary AIR system to avoid being severely burned.

AIR Pump
5.7L (VIN 8) ENGINE

See Figures 1 and 2

  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. Lift the drive belt tensioner to the raised position and remove the belt.
  6.  
  7. If necessary, insert needle-nose pliers and pull the filter fan from the hub.
  8.  
  9. Disconnect the hoses, vacuum and electrical connections from the AIR control valve.
  10.  
  11. Unfasten the AIR pump mounting bolts, then remove the pump assembly.
  12.  
  13. If the pump is being replaced, transfer the air injection control valve to the new pump.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: AIR pump filter fan removal-1984 5.7L (VIN 8) engine shown



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the air pump removal-1984 5.7L (VIN 8) engine shown

To install:
  1. Position the AIR pump assembly and secure with the mounting bolts.
  2.  
  3. Attach the hoses, vacuum and electrical connections and control valve.
  4.  
  5. Install a new filter fan on the pump hub.
  6.  
  7. Place the pump pulley against the centrifugal filter fan.
  8.  
  9. Instlal the pump pulley bolts and tighten equally and evenly to 100 inch lbs. (12 Nm). This will compress the fan onto the pump hole. Do not try to drive the fan on with a hammer. A slight amount of interference with the housing bore is normal. After a new fan is installed, it may squeal when it is first operated, until the sealing lip has worn in. This may require a short period of pump operation at various engine speeds.
  10.  
  11. Install the serpentine drive belt.
  12.  
  13. Instlal the AIR pump pulley and secure with the retaining bolts.
  14.  
  15. Connect the negative battery cable and check the AIR system for proper operation.
  16.  

5.7L (VIN J) AND 1992-93 5.7L (VIN P) ENGINE

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the electric air pump.
  4.  
  5. Disconnect the outlet hose.
  6.  
  7. Unfasten the electric air pump mounting bolts from the front member.
  8.  
  9. Loosen the inlet silencer clamp.
  10.  
  11. Remove the electric air pump mounting bolts, then remove the air pump.
  12.  
  13. If replacing the air pump, remove the pump from the bracket.
  14.  



Click image to see an enlarged view

Fig. Fig. 3: Exploded view of the AIR pump mounting-5.7L (VIN J) engine shown, 1992-93 5.7L (VIN 8) similar

To install:
  1. If removing, install the electric AIR pump mounting bracket to the electric AIR pump assembly.
  2.  
  3. Install the mounting bolts and tighten to 50 inch lbs. (5.6 Nm).
  4.  
  5. Install the electric air pump and inlet silencer and tighten the inlet silencer clamp to 2 inch lbs. (0.2 Nm).
  6.  
  7. Install the air pump mounting bolts to the front member and tighten to 89 inch lbs. (10 Nm).
  8.  
  9. Connect the outlet hose and tighten the hose clamp to 2 inch lbs. (0.2 Nm).
  10.  
  11. Attach the electrical connectors to the air pump.
  12.  
  13. Connect the negative battery cable, then check the system for proper operation.
  14.  

1994-96 5.7L (VIN P and 5) engines

See Figure 4

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the air pump.
  4.  
  5. Disconnect the outlet and inlet hoses.
  6.  
  7. Remove the air pump mounting bolts from the bracket, then remove the pump from the bracket.
  8.  



Click image to see an enlarged view

Fig. Fig. 4: Exploded view of the air pump mounting-1994-96 5.7L (VIN P and 5) engines

To install:
  1. Position the air pump to the bracket and secure with the mounting bolts. Tighten the bolts to 50 inch lbs. (5.6 Nm).
  2.  
  3. Connect the outlet and inlet hoses to the pump.
  4.  
  5. Attach the air pump electrical connector.
  6.  
  7. Connect the negative battery cable, then check for proper system operation.
  8.  

Air Injection Control Valve
5.7L (VIN 8) engine

See Figure 5

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the adapter bolts.
  4.  
  5. Disconnect the air outlet hoses from the valve.
  6.  
  7. Remove the air cleaner cover.
  8.  
  9. Remove the adapter.
  10.  



Click image to see an enlarged view

Fig. Fig. 5: Location of the AIR system control and check valves and related components-5.7L (VIN 8) engine

  1. Detach the electrical connectors and vacuum hoses from the valve.
  2.  
  3. Remove the control valve from the vehicle.
  4.  
  5. Installation is the reverse of the removal procedure.
  6.  

AIR Electric Diverter Valve (EDV)
5.7L (VIN J) and 1992-93 5.7L (VIN P) engines

See Figure 6

On later models, the valve is also referred to as the Electric Switching Valve (ESV)

  1. Disconnect the negative battery cable.
  2.  
  3. Unfasten the mounting bracket bolt.
  4.  
  5. Disconnect the air inlet and outlet hoses from the valve.
  6.  
  7. Detach the electric connector and vacuum hose from the valve.
  8.  
  9. Unfasten the electric diverter valve mounting bracket bolts, then remove the valve.
  10.  



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of the Electric Diverter Valve (EDV)

To install:
  1. Position the diverter valve to the mounting bracket and secure with the retaining bolts. Tighten the bolts to 17 ft. lbs. (24 Nm).
  2.  
  3. Attach the electrical connector and vacuum hose. Connect the air hoses to the valve.
  4.  
  5. Install the mounting bracket bolt(s) and tighten to 106 inch lbs. (12 Nm).
  6.  
  7. Connect the negative battery cable, then check the AIR system for proper operation.
  8.  

Air Check Valve
5.7L (VIN 8) engine

See Figure 5

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

To install:
  1. Screw the check valve onto the air injection pipe.
  2.  
  3. Position the air hose on the check valve and secure with the clamp.
  4.  

5.7L (VIN J, P and 5)

See Figures 7 and 8

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the clamp and air hoses from the EDV left check valve pipe, or AIR system right pipe, as applicable.
  4.  
  5. Remove the check valve clamps.
  6.  
  7. Slide the connector pipes together.
  8.  
  9. Remove the left or right check valve pipe, as applicable.
  10.  
  11. Unscrew the check valve from the air injection pipe.
  12.  



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the left check valve assembly-5.7L (VIN J) shown, others similar



Click image to see an enlarged view

Fig. Fig. 8: Location of the right check valve and pipes-5.7L (VIN J) shown, others similar

To install:
  1. Screw the check valve onto the air injection pipe. Tighten the check valves to 14 ft. lbs. (19 Nm).
  2.  
  3. If installing the left check valve, place the valve pipe assembly between the check valves and push the connector pipes out.
  4.  
  5. If removed, install the right check valve pipe.
  6.  
  7. Position the clamps and tighten to 15 inch lbs. (1.7 Nm).
  8.  
  9. Connect the air hose to the left or right check valve pipe, as applicable.
  10.  
  11. Position the clamp and tighten to 15 inch lbs. (1.7 Nm).
  12.  
  13. Connect the negative battery cable.
  14.  

 
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