Honda Civic/CRX/del Sol 1984-1995 Repair Guide

Idle Speed

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ADJUSTMENT



Carbureted Engines

See Figures 1 through 5



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Fig. Fig. 1: Clamp off the air intake control vacuum hose-1985-87 carbureted models



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Fig. Fig. 2: Adjust the curb idle at the throttle stop screw-1984-87 carbureted models

The idle mixture adjustment on these vehicles is controlled by the PGM-FI Engine Control Unit (ECU) and is therefore not adjustable. For further fuel system diagnosis, refer to Fuel System of this information. The following applies to carbureted engines only.

  1. Operate the engine until normal operating temperature is reached.
  2.  
  3. Remove the vacuum hose from the intake air control diaphragm and clamp the hose end.
  4.  
  5. Connect a tachometer to the engine.
  6.  
  7. With all accessories (headlights, heater blower, rear window defroster, cooling fan and air conditioner) OFF, adjust the idle speed by turning the throttle stop screw to the rpm listed in the Tune-Up Specifications chart found in this section or the underhood sticker.
  8.  

If the underhood sticker disagrees in any way with the Tune-Up specifications chart, always defer to the sticker.

  1. After the idle is adjusted, remove the tachometer and reconnect the vacuum hose.
  2.  



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Fig. Fig. 3: To correctly adjust the idle on fuel injected models, disconnect the No. 10 hose, then cap it and the intake manifold



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Fig. Fig. 4: Location of idle adjusting screw on the throttle body



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Fig. Fig. 5: Use adjusting screw B (shown) to set idle speed while A/C is on after the no-load idle adjustment has been performed

Fuel Injected Engines
1985-87 MODELS
  1. Start the engine and warm it up to normal operating temperature. Allow the cooling fan to come on at least once.
  2.  
  3. Connect a tachometer.
  4.  
  5. Disconnect the No. 10 vacuum hose from the intake manifold. (Refer to the vacuum diagram in Emission Controls .)
  6.  
  7. Cap the end of the hose and intake manifold
  8.  
  9. Check the idle speed with no electrical system load, headlights, heater blower, rear window defogger, cooing fan and A/C should be off. Adjust the idle speed if necessary, by turning the adjusting screw on the top of the throttle body.
  10.  
  11. Idle speed should be: 700-800 rpm.
  12.  
  13. Next check the idle speed with the A/C on.
  14.  
  15. Idle speed should be 700-800 rpm.
  16.  
  17. If necessary, adjust by turning adjusting screw B.
  18.  

1988-91 MODELS

See Figures 6 through 9

  1. Start the engine and warm it up to normal operating temperature. Allow the cooling fan to come on at least once.
  2.  
  3. Connect a tachometer.
  4.  
  5. Disconnect the 2P connector from the Electronic Air Control Valve (EACV).
  6.  
  7. Set the front wheels in the straight ahead position and check the idle speed with the headlights, blower fan, rear defroster, cooling fan and air conditioner not operating. Vehicles with automatic transaxle should be checked with the transaxle in N or P.
  8.  



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Fig. Fig. 6: Disconnect the 2P wire from the EACV to set the idle speed-1988-91 1.5L engine



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Fig. Fig. 7: Idle adjustment screw-1988-91 1.5L engine



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Fig. Fig. 8: Disconnect the 2P wire from the EACV to set the idle speed-1988-91 1.6L engine



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Fig. Fig. 9: Idle adjustment screw-1988-91 1.6L engine

  1. The idle speed should be as follows:
  2.  



All Civics and CRX with 1.5L engine-575-675 rpm
 
CRX HF-450-550 rpm
 
Civic/CRX Si, and 4WD wagon-500-600 rpm
 

  1. Adjust the idle speed, if necessary, by turning the adjusting screw.
  2.  

If the idle speed is excessively high on Civic and CRX, check the throttle control system.

  1. Turn the ignition switch OFF .
  2.  
  3. Reconnect the 2P connector on the EACV.
  4.  
  5. On Civic and CRX, remove the HAZARD fuse in the main fuse box for 10 seconds to reset the ECU.
  6.  

1992-95 MODELS

See Figures 10 and 11

  1. Start the engine and warm it up to normal operating temperature. Allow the cooling fan to come on at least once.
  2.  
  3. Connect a tachometer.
  4.  
  5. Disconnect the 2P connector from the Idle Air Control Valve (IAC)
  6.  

In 1993 Honda re-named the Electronic Air Control Valve (EACV) the Idle Air Control Valve (IAC). They are the same part.

  1. Start the engine with the accelerator pedal slightly depressed. Stabilize the rpm at 1000, then slowly release the pedal until the engine settles into its idle. Vehicles with automatic transaxle should be checked with the transaxle in N or P. The idle speed should be:
  2.  



370-470 rpm
 

  1. Adjust the idle speed, if necessary, by turning the idle adjusting screw.
  2.  
  3. Turn the ignition switch OFF .
  4.  
  5. Reconnect the 2P connector on the IAC, then remove the BACK UP (7.5A) fuse in the under hood fuse/relay box for 10 seconds to reset the ECM.
  6.  

In 1993 Honda re-named the Electronic Control Unit (ECU) the Engine Control Module (ECM). They are the same part.



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Fig. Fig. 10: Location of the Idle Air Control IAC valve. This is known as the EACV up to 1992



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Fig. Fig. 11: Location of the idle adjusting screw-1992-95

 
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