Hyundai Coupes/Sedans 1986-1993 Repair Guide

Idle Speed

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IDLE SPEED ADJUSTMENT



Carbureted Engines

See Figures 1 and 2

The idle speed is adjusted periodically to compensate for engine wear or after engine work is performed. Idle mixture adjustments are not required as routine adjustments, but only when major carburetor work has been completed. If idle speed adjustment is required, adjust under the following conditions:



Lights Off
 
All accessories Off
 
Electric cooling fan Off
 
Transaxle in neutral and parking brake applied
 

  1. Start and run the engine at idle until normal operating temperature is reached.
  2.  
  3. Check the underhood decal or the tune-up specification charts for the correct curb idle speed.
  4.  
  5. Connect a tachometer, according to the manufacturer's instructions and adjust the idle speed screw until the correct rpm is reached.
  6.  
  7. Run the engine for at least 5 seconds at 2000-3000 rpm. Then, reduce the speed to idle rpm for at least 2 minutes.
  8.  
  9. If the idle speed is not at the specified rpm, turn the idle speed adjusting screw until the proper rpm is reached.
  10.  



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Fig. Fig. 1: Carburetor adjustment points



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Fig. Fig. 2: Idle speed adjustment point-carbureted engines

  1. Check the underhood specifications sticker for the correct idle speed rpm.
  2.  

Fuel Injected Engines
1468cc ENGINE

See Figures 3 through 7

  1. Warm the engine to operating temperature, leave lights, electric cooling fan and accessories OFF . The transaxle should be in N . The steering wheel in a neutral position for vehicles with power steering.
  2.  
  3. Loosen the accelerator cable.
  4.  
  5. Turn the ignition switch ON but do not start the engine. Leave the key in this position for at least 15 seconds. Check to see that the ISC servo is fully retracted to the curb idle position.
  6.  

When the ignition switch is turned to the ON position, the ISC plunger extends to the fast idle position opening. After 15 seconds, it retracts to the fully closed (curb idle) position.

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the ISC motor connector and secure the ISC motor at the fully retracted position.
  4.  



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Fig. Fig. 3: ISC control cable adjustment points



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Fig. Fig. 4: Multi-tester connections for ISC adjustment



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Fig. Fig. 5: Speed control screws for fuel injected engines



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Fig. Fig. 6: Diagnostic connector and idle speed adjusting screw-2972cc engine



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Fig. Fig. 7: Ignition coil terminal with paper clip inserted

  1. In order to prevent the throttle valve from sticking, open it 2 or 3 times, then allow it to click shut and loosen the fixed SAS sufficiently.
  2.  
  3. Start the engine and allow it to run at idle speed. Ensure that the engine is running at idle speed of 700 rpm plus or minus100. Adjust as necessary by turning the ISC adjust screw.
  4.  
  5. Tighten the fixed SAS until the engine speed starts to increase. Then, loosen the screw until the engine speed ceases to drop (touch point) and loosen an additional 1 / 2 turn.
  6.  
  7. Turn the ignition switch to the OFF position.
  8.  
  9. Adjust the accelerator cable to 0-0.04 in. (0-1mm) for a manual transaxle and 0.08-0.12 in. (2-3mm) for an automatic transaxle.
  10.  
  11. Connect the ISC motor connector.
  12.  
  13. Start the engine and check to be sure that the idle speed is correct.
  14.  
  15. Turn the ignition switch OFF and disconnect the negative battery cable for 15 seconds and re-connect. This will erase the data stored in memory during ISC adjustment.
  16.  

2351cc ENGINE
  1. Warm the engine to operating temperature, leave lights, electric cooling fan and accessories OFF . The transaxle should be in N . The steering wheel in a neutral position for vehicles with power steering.
  2.  
  3. Loosen the accelerator cable.
  4.  
  5. Insert the paper clip into the 1 terminal rpm connector in the engine compartment, and connect the primary voltage detection type tachometer to the paper clip.
  6.  
  7. Ground the self-diagnostic control terminal of the diagnostic connector with a jumper wire.
  8.  
  9. Turn the ignition switch ON but do not start the engine. Leave the key in this position for at least 15 seconds. Check to see that the ISC servo is fully retracted to the curb idle position.
  10.  

When the ignition switch is turned to the ON position, the ISC plunger extends to the fast idle position opening. After 15 seconds, it retracts to the fully closed (curb idle) position.

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the ISC motor connector to secure the ISC motor at the fully retracted position.
  4.  
  5. In order to prevent the throttle valve from sticking, open it 2 or 3 times, then allow it to click shut and loosen the fixed SAS sufficiently.
  6.  
  7. Start the engine and allow it to run at idle speed. Ensure that the engine is running at idle speed of 700 rpm plus or minus 50. Adjust as necessary by turning the ISC adjust screw.
  8.  
  9. Tighten the fixed SAS until the engine speed starts to increase. Then, loosen the screw until the engine speed ceases to drop (touch point) and loosen an additional 1 / 2 turn.
  10.  
  11. Turn the ignition switch to the OFF position.
  12.  
  13. Adjust the accelerator cable to 0-0.04 in. (0-1mm) for a manual transaxle and 0.08-0.12 in. (2-3mm) for an automatic transaxle.
  14.  
  15. Connect the ISC motor connector.
  16.  
  17. Start the engine and check to be sure that the idle speed is correct.
  18.  
  19. Turn the ignition switch to the OFF and disconnect the negative battery cable for 15 seconds and re-connect. This will erase the data stored in memory during ISC adjustment.
  20.  

1596cc, 1997cc and 2972cc ENGINES
  1. Warm the engine to operating temperature, leave lights, electric cooling fan and accessories OFF . The transaxle should be in N . The steering wheel in a neutral position for vehicles with power steering.
  2.  
  3. Loosen the accelerator cable.
  4.  
  5. Connect a multi-use tester to the diagnostic connector in the fuse box. If a multi-use tester is not being used, connect a tachometer to the engine and ground the self-diagnostic terminal.
  6.  
  7. Ground the ignition timing adjustment terminal in the engine compartment.
  8.  
  9. Run the engine for more than 5 seconds at an engine speed of 2000-3000 rpm. Allow the engine to return to idle for a minimum of 2 minutes.
  10.  
  11. Check that the engine is within the desired reading of 700-750 rpm. If the multi-use tester is being used, press code No. 22 and read the engine timing.
  12.  

The engine speed on a new vehicle driven less than 300 miles may be 100 rpm lower than the desired rpm, in which case it would not require adjustment. Break-in should take approximately 300 miles. If the vehicle stalls or has a very low idle speed, suspect a deposit buildup on the throttle valve which must be cleaned.

  1. If the basic engine idle speed is out of specification, adjust by turning the Speed Adjusting Screw (SAS), until the desired reading is obtained.
  2.  
  3. Turn the ignition switch OFF and stop the engine. Disconnect the jumper wire from the diagnosis connector, disconnect the jumper wire from the ignition timing connector and reconnect the waterproof connector. Disconnect the tachometer.
  4.  
  5. Restart the engine, allow to run for 10 minutes and check for good idle quality.
  6.  

IDLE MIXTURE ADJUSTMENT



Carbureted Engines

The idle mixture adjustment is preset at the factory. The mixture adjusting screw is inaccessible without removing and modifying the carburetor. Since this adjustment is preset, it should not be changed as part of a routine tune-up.

USA VEHICLES
  1. Disconnect the negative battery cable. Remove the carburetor. The idle mixture screw is located in the base of the carburetor, just to the left of the PCV hose. Mount the carburetor, carefully, in a soft-jawed vise, protecting the gasket surface and with the mixture adjusting screw facing upward.
  2.  
  3. Drill a 1/8 in. (2mm) hole through the casting from the underside of the carburetor. Make sure the hole intersects the passage leading to the mixture adjustment screw just behind the plug. Now, widen that hole with a 3mm ( 1 / 8 in.) drill bit.
  4.  
  5. Insert a blunt punch into the hole and tap out the plug. Install the carburetor on the engine and connect all hoses, lines, etc. Connect the negative battery cable.
  6.  
  7. Start the engine and run it at fast idle until it reaches normal operating temperature. Make sure all accessories are OFF and the transaxle is in neutral. Turn the ignition switch OFF and disconnect the negative battery cable for about 3 seconds, then, reconnect it. Disconnect the oxygen sensor.
  8.  
  9. Start the engine and run it for at least 5 seconds at 2000-3000 rpm. Then, allow the engine to idle for about 2 minutes.
  10.  
  11. Connect a tachometer and allow the engine to operate at the specified curb idle speed. Adjust it, if necessary, to obtain this speed. Connect a CO meter to the exhaust pipe. A reading of 0.1-0.3 percent is necessary. Adjust the mixture screw to obtain the reading. If, during this adjustment, the idle speed is varied more than 100 rpm in either direction, reset the idle speed and readjust the CO until both specifications are met simultaneously. Shut off the engine, reconnect the oxygen sensor and install a new concealment plug.
  12.  

CANADIAN VEHICLES
  1. Disconnect the negative battery cable. Turn off all of the electrical accessories and place the transaxle in the neutral position. Then remove the carburetor from the engine.
  2.  
  3. Position the carburetor in a vise with idle mixture adjusting screw facing up. Make sure the gasket surface does not become damaged when the carburetor is placed in the vise.
  4.  
  5. Drill a 1/8 in. (2mm) pilot hole in the casting surrounding the idle mixture adjusting screw, then redrill the hole to 1 / 8 in. (3mm). Insert a blunt punch into the hole and drive out the plug.
  6.  
  7. Reinstall the carburetor. Run the engine until it reaches normal operating temperature.
  8.  
  9. Run the engine for 5 seconds or more at 2000-3000 rpm. Allow the engine to idle for 2 minutes.
  10.  
  11. Set the idle CO and the engine speed to specifications, by adjusting the idle speed adjusting screw No. 1 (SAS-1) and the idle mixture adjusting screw. Idle CO should be 1.8 percent when the curb idle speed is set between 850-900 rpm.
  12.  
  13. Install the concealment plug to seal the idle mixture adjusting screw.
  14.  

Fuel Injected Engines

The fuel mixture is controlled and governed by the Electronic Control Unit (ECU). No mixture adjustment is necessary on the system.

 
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