Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Exhaust Gas Recirculation System-Rotary Engine

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OPERATION



1980 California RX-7s and all 1986-89 models are equipped with a system for recirculating exhaust gases from the thermal reactor/exhaust manifold and introducing them into the combustion chamber, in order to lower the combustion chamber temperature and prevent the formation of oxides of nitrogen (NOx). The system consists of an EGR valve, an EGR valve solenoid, a vacuum switch and No. 1 water temperature sensor (1980 only).

EGR SYSTEM TESTING



1980 RX-7

See Figure 1

  1. Run the engine until it reaches normal operating temperature, and connect a tachometer to the engine.
  2.  
  3. Connect a voltmeter to the brown and yellow wire in the electrical connector of the EGR solenoid valve.
  4.  
  5. Start the engine and quickly rev it to 2,500 rpm. Current should flow to the terminal for a few seconds and then stop.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Detach the connector from the No. 1 water temperature switch, and connect a jumper wire-1980 RX-7

  1. Disconnect the electrical coupler of the vacuum switch and connect a jumper wire to both terminals in the coupler. Increase engine speed with the throttle. Current flow to the solenoid valve should stop when the engine speed is 2,700-3,300 rpm for manual transmission models, or 3,000-3,600 rpm for automatic transmission models.
  2.  
  3. Increase the engine speed to 2,000 rpm with the throttle. Slowly decrease the engine speed and record the engine speed at which the current stops flowing to the terminal. Engine speed should be around 1,050-1,250 rpm.
  4.  
  5. Slowly increase the engine speed from idle and check the engine speed at which the current begins to flow. Compare this figure with that recorded in Step 5. The difference in engine speed between the two should be about 90-220 rpm.
  6.  
  7. On vehicles equipped with a manual transmission, increase the engine speed to 2,000 rpm with the throttle. Current flow to the terminal should stop when the idle switch lever is fully pushed up to the idle position.
  8.  
  9. Disconnect the coupler of the No.1 water temperature switch, then connect a jumper wire to both terminals on the wiring harness, as illustrated. No current should flow to the solenoid valve at any rpm.
  10.  
  11. Stop the engine, then start the engine with the choke knob pulled fully out, and set the engine speed at 2,000 rpm with the choke knob. Current should flow to the solenoid after 104-156 seconds from the time the engine was started with the choke valve pulled out.
  12.  
  13. On vehicles with a manual transmission, set the engine speed to 2,000 rpm using the throttle, then depress the clutch pedal and shift the transmission into 4th and 5th gears. Current to the solenoid should stop when the gears are engaged.
  14.  
  15. If the results of all tests are as described above, the EGR signal system is working properly.
  16.  

EGR VALVE TESTING



The EGR valve is located between the air cleaner and the bank of solenoid valves on the engine.

  1. Run the engine to operating temperature, then shut it off.
  2.  
  3. Disconnect the vacuum sensing tube from the EGR valve, and connect a vacuum pump to the valve.
  4.  
  5. Start the engine and run it at idle. The engine should operate smoothly.
  6.  
  7. Apply a vacuum of 15.7 in. Hg (399mm Hg) for 1980 models, or 3.9 in. Hg (99mm Hg) for 1986-89 models to the EGR valve. The engine should stall or experience a sharp drop in speed if the valve is working properly.
  8.  

EGR SOLENOID VALVE TESTING



1980 RX-7 (California Only)

The EGR solenoid valve is located in the bank of solenoids on the engine and can be identified by the gray dab of paint on its body.

  1. Disconnect the vacuum sensing tubes from the solenoid valve and the vacuum pipe.
  2.  
  3. Blow through the solenoid valve from tube B . Air should come out of air filter A on the valve.
  4.  
  5. Detach the electrical connection from the EGR solenoid valve, then activate the valve using jumper cables from the battery.
  6.  
  7. Blow through vacuum tube B . Air should come out of port C .
  8.  
  9. If the solenoid does not operate as indicated above, replace it.
  10.  

1986-89 RX-7 (All Models)

See Figures 2 and 3

The EGR solenoid valve is located in the bank of solenoids on the engine. It supplies intake manifold vacuum to the EGR valve.

  1. Locate the EGR valve in the engine solenoid valve bank, and disconnect the vacuum hose from the valve (see illustration).
  2.  



Click image to see an enlarged view

Fig. Fig. 2: EGR solenoid valve location on 1986-89 RX-7



Click image to see an enlarged view

Fig. Fig. 3: Checking EGR solenoid valve on 1986-89 RX-7

  1. Blow into the solenoid valve through port B and place your hand under the air filter. Air should pass freely through the valve and exit from the air filter.
  2.  
  3. Detach the connector from the solenoid valve, then connect a 12-volt power source and a ground to the solenoid terminals. Blow through port B of the valve and place your hand over the opening of port A . Air should pass freely through the valve and exit through port A .
  4.  
  5. If the air flow is not as described above, replace the solenoid valve.
  6.  

 
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