Hyundai Coupes/Sedans 1994-1998 Repair Guide

Idle Speed and Mixture Adjustments

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All engines covered in this guide utilize sophisticated multi-port fuel injection systems. Based on information from various sensors, an engine control computer constantly adjusts and maintains proper idle speed and mixture to meet driving conditions. No periodic adjustments are necessary.

If idle speed is not within specification, check the spark plugs, injectors, idle speed control actuator, compression and general engine tune-up prior to attempting adjustments.

Most often idle speed problems are the result of a deposit buildup on the throttle valve. Deposits can be cleaned with a special cleaner designed specifically for throttle bodies.

On some engines, idle speed adjustments can be made when replacement parts are installed on the vehicle. These adjustments should only be made if all other possibilities have been exhausted. If a problem is suspected, refer to Fuel System and Fuel System of this guide for more information.

ADJUSTMENT



1.5L (VIN J) Engine

See Figures 1 and 2

  1. Warm the engine to operating temperature. Ensure the lights, electric cooling fan and accessories are off. The transaxle should be in P or N . The steering wheel should be in the straight ahead position for vehicles with power steering.
  2.  
  3. Install a tachometer by disconnecting the noise filter connector and installing a special tool (SST 09273-24000), or equivalent, between them. Connect the tachometer to the special tool.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Install a tachometer by detaching the noise filter connector and installing a special tool (SST 09273-24000), or equivalent, between them. Connect the tachometer to the special tool

A scan tool may be connected to the diagnostic connector in the fuse box to read engine rpm if a tachometer and special tool are not available.

  1. Start the engine and allow it to idle.
  2.  
  3. Run the engine for 5 seconds or more at 2,000-3,000 rpm. Then allow the engine to idle for 2 minutes.
  4.  
  5. Check and note the engine idle speed.
  6.  
  7. If idle speed is not within specification, first check for proper ignition timing. If ignition timing is within specification, proceed as follows.
  8.  
  9. Loosen the accelerator cable.
  10.  
  11. 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 Idle Speed Control (ISC) servo is fully retracted to the curb idle position.
  12.  

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.
  4.  
  5. In order to prevent the throttle valve from sticking, open it 2 or 3 times, then allow it to click shut. Loosen the fixed Speed Adjusting Screw (SAS) sufficiently.
  6.  
  7. Start the engine and allow it to run at idle speed. Turn the ISC adjusting screw to obtain proper idle speed.
  8.  



Click image to see an enlarged view

Fig. Fig. 2: Fixed Speed Adjusting Screw (SAS) and Idle Speed Control (ISC) adjusting screw locations-1.5L (VIN J) engine

  1. 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.
  2.  
  3. Turn the ignition switch OFF .
  4.  
  5. Turn the ignition switch ON but do not start the engine.
  6.  
  7. Check Throttle Position Sensor (TPS) output voltage. If voltage is not within specification, adjust TPS.
  8.  
  9. Turn the ignition switch OFF and adjust the accelerator cable.
  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 , disconnect the negative battery cable for 15 seconds and re-connect. This will erase the data stored in memory during ISC adjustment.
  16.  

1.6L (VIN R) and 1.8L (VIN M) Engines

See Figures 3 and 4

  1. Warm the engine to operating temperature. Ensure that the lights, electric cooling fan and accessories are off. The transaxle should be in P or N . The steering wheel should be in the straight ahead position for vehicles with power steering.
  2.  
  3. Install a tachometer by disconnecting the noise filter connector and installing a special tool (SST 09273-24000), or equivalent, between them. Connect the tachometer to the special tool.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Install a tachometer by detaching the noise filter connector and installing a special tool (SST 09273-24000), or equivalent, between them. Connect the tachometer to the special tool

A scan tool may be connected to the diagnostic connector in the fuse box to read engine rpm if a tachometer and special tool are not available.

  1. Start the engine and allow it to idle.
  2.  
  3. Check and adjust basic ignition timing to specification. Leave the ignition timing adjustment terminal grounded.
  4.  
  5. Check and note basic idle speed.
  6.  
  7. If idle speed is not within specification, loosen the accelerator cable.
  8.  
  9. Run the engine for 5 seconds or more at 2,000-3,000 rpm and them allow it to idle for 2 minutes.
  10.  
  11. Check and note the engine idle speed.
  12.  

If the engine stalls or engine speed is low, check for deposits on the throttle valve area. Clean deposits with throttle body cleaner.

  1. If idle speed is not within specification, adjust the Speed Adjusting Screw (SAS) until proper idle speed is obtained.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Turn the Speed Adjusting Screw (SAS) until proper idle speed is obtained-1.6L (VIN R), 1.8L (VIN M) and 2.0L (VIN P) engines

If idle speed is higher than specification, even with the SAS fully closed, check whether the idle switch has been previously adjusted. If the switch has been moved, re-adjust the idle switch to proper specification.

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the scan tool or tachometer. Unground the data link connector and ignition timing connector, as necessary.
  4.  
  5. Start the engine and allow it to idle for 10 minutes or more. Check for proper idle.
  6.  

2.0L (VIN P) Engine

See Figure 4

  1. Warm the engine to operating temperature. Ensure that the lights, electric cooling fan and accessories are off. The transaxle should be in P or N . The steering wheel should be in the straight ahead position for vehicles with power steering.
  2.  
  3. Connect a scan tool to the data link connector in the fuse box.
  4.  
  5. If a scan tool is not available, connect a tachometer to the engine and ground the diagnostic link connector.
  6.  
  7. Ground the ignition timing adjustment terminal.
  8.  
  9. Run the engine for 5 seconds or more at 2,000-3,000 rpm and them allow it to idle for 2 minutes.
  10.  
  11. Check and note the engine idle speed.
  12.  

If idle speed is higher than specification, even with the SAS fully closed, check whether the idle switch has been previously adjusted. If the switch has been moved, re-adjust the idle switch to proper specification.

  1. If idle speed is not within specification, adjust the Speed Adjusting Screw (SAS) until proper idle speed is obtained.
  2.  
  3. Turn the ignition switch OFF .
  4.  
  5. Disconnect the scan tool or tachometer. Unground the data link connector and ignition timing connector, as necessary.
  6.  
  7. Start the engine and allow it to idle for 10 minutes or more. Check for proper idle.
  8.  

 
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