Subaru Coupes/Sedans/Wagons 1985-1996 Repair Guide

Idle Speed and Mixture

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ADJUSTMENT



Manual Carburetor

See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Adjust the idle by rotating the throttle adjusting screw

Inspection of engine idle speed should be carried out after checking the ignition timing and intake and exhaust valve clearances (except hydraulic lifter equipped models).

  1. Position gear selector lever in the N position on vehicles equipped with manual transaxles, and in the P position on vehicles equipped with automatic transaxles. Connect a tachometer in accordance with the manufacturer's instructions.
  2.  
  3. Start the engine and allow it to reach normal operating temperature.
  4.  
  5. Disconnect and plug the air suction hose on the air cleaner and the purge hose leading to the purge canister.
  6.  
  7. Check and adjust the engine to the proper idle speed by turning the throttle adjusting screw.
  8.  
  9. Remove the tachometer.
  10.  

Electronic Feedback Carburetor (EFC)
WITHOUT AIR CONDITIONING

See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: Location of throttle adjusting and idle-up adjusting screw

Before checking or adjusting the idle speed, check the ignition timing and adjust, if necessary.

  1. Position gear selector lever in the N position on vehicles equipped with manual transaxles, and in the P position on vehicles equipped with automatic transaxles.
  2.  
  3. Connect the Test Mode connector and the Read Memory connector located under the left side of the dash.
  4.  
  5. Start the engine and allow it to reach normal operating temperature. Then, run engine at 2500 rpm for 1 minute.
  6.  
  7. Disconnect and plug the purge hose at the intake manifold,
  8.  
  9. To adjust the Idle-up system OFF, turn all accessories OFF and adjust idle to specification by rotating the throttle adjusting screw.
  10.  
  11. To adjust the Idle-up system ON, turn the headlights ON and adjust the idle by rotating the idle-up adjusting screw.
  12.  
  13. Turn the headlights OFF .
  14.  

WITH AIR CONDITIONING

See Figure 3

Click image to see an enlarged view

Fig. Fig. 3: Location of fast-idle, throttle adjusting and idle-up adjusting screws

Before checking or adjusting the idle speed, check the ignition timing and adjust, if necessary.

  1. Position gear selector lever in the N position on vehicles equipped with manual transaxles, and in the P position on vehicles equipped with automatic transaxles.
  2.  
  3. Fasten the Test Mode connector and the Read Memory connector located under the left side of the dash.
  4.  
  5. Start the engine and allow it to reach normal operating temperature. Then, run engine at 2500 rpm for 1 minute.
  6.  
  7. Disconnect and plug the purge hose at the intake manifold,
  8.  
  9. To adjust the Idle-up system OFF, turn all accessories and A/C OFF and adjust idle to specification by rotating the throttle adjusting screw.
  10.  
  11. To adjust the Idle-up system ON, turn the A/C ON and adjust the idle by rotating the fast-idle adjusting screw.
  12.  
  13. Turn the headlights ON and turn the A/C OFF and check the idling speed. If adjustment is needed, loosen the locknut and rotate the idle-up adjusting screw.
  14.  
  15. When complete. disconnect the test mode and read memory connectors. Remove the tachometer.
  16.  

Fuel Injection
1.6L, 1.8L AND 2.7L ENGINES

See Figures 4 and 5

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Fig. Fig. 4: Idle adjustment screw-1.6L and 1.8L engines



Click image to see an enlarged view

Fig. Fig. 5: Idle adjustment screw-2.7L engines

  1. Position gear selector lever in the N position on vehicles equipped with manual transaxles, and in the P position on vehicles equipped with automatic transaxles.
  2.  
  3. Connect a tachometer according to the manufacturer's instructions. Start the engine and allow it to reach normal operating temperature.
  4.  
  5. Check and adjust the ignition timing to specification.
  6.  
  7. Check and make sure all vacuum hoses, blow-by hoses, rocker cover, oil filler cap and oil filter are secure.
  8.  
  9. Increase engine speed to 2500 rpm for 1 minute to heat the oxygen sensor.
  10.  
  11. Disconnect and plug the purge hose leading to the throttle body.
  12.  
  13. Disconnect the air control valve electrical connector from the throttle body.
  14.  
  15. Inspect the auxiliary air control valve attached to the intake manifold, and make sure it is closed.
  16.  
  17. Access the idle adjusting screw located at the side of the throttle body and rotate to adjust the idle.
  18.  
  19. When complete, connect all hoses plugged earlier.
  20.  
  21. Remove the tachometer.
  22.  

2.2L, 2.5L AND 3.3L ENGINES
  1. Position gear selector lever in the N position on vehicles equipped with manual transaxles, and in the P position on vehicles equipped with automatic transaxles.
  2.  
  3. Check and make sure the ignition timing is correct, the spark plugs are gapped correctly and in good condition, and the air filter is clean.
  4.  
  5. Inspect all vacuum hoses for any leaks, and repair if needed.
  6.  
  7. Check and make sure the CHECK ENGINE light does not illuminate.
  8.  
  9. Connect the Subaru select monitor to the harness located under the left side of the dash. When connected use mode F04 for this procedure.
  10.  


WARNING
When connecting the Subaru select monitor, make sure the ignition is OFF, or damage could occur to the monitor and or ignition components.

On 1995-96 models, an OBD-II scan tool can be used in place of the Subaru select monitor. Refer to the instruction guide for the proper operation procedures.

  1. With all accessories OFF , check the idle speed. The idle range should be 600-800 rpm.
  2.  
  3. Check the idle speed when loaded by turning ON the headlights, rear defroster and A/C. The idle range should be 800-900 rpm. If not, diagnose and correct the problem in the fast idle control device (FICD) system.
  4.  


WARNING
If the idle speed is not within specification range, DO NOT turn the idle adjusting screw. If repairs to the FICD do not restore the idle to specification, consult an authorized dealer for additional repairs.

  1. Disconnect the test mode connector.
  2.  

 
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