GM Cutlass RWD 1970-1987 Repair Guide

Idle Speed

Print

See Figures 1 and 2

1978 2 GC, 2 GE Carburetor

  1. Run the engine to normal operating temperature. Make sure that the choke is fully opened, set the parking brake, block the drive wheels, turn the air conditioning Off and connect a tachometer to the engine according to the manufacturer's instructions.
  2.  
  3. Disconnect and plug the vacuum hoses at the vapor canister and EGR valve.
  4.  
  5. Place the transmission in Park (AT) or Neutral (MT).
  6.  
  7. Disconnect and plug the vacuum advance hose at the distributor. Set the ignition timing.
  8.  
  9. Reconnect the vacuum advance hose and turn the idle speed screw to obtain the specified rpm.
  10.  
  11. Connect all hoses and remove the tachometer.
  12.  

1978-80 M2ME/M2MC/E2ME-210 Carburetor

  1. Run the engine to normal operating temperature.
  2.  
  3. Make sure that the choke is fully opened, set the parking brake, block the wheels, connect a tachometer to the engine according to the manufacturer's instructions, disconnect the compressor clutch wire, turn the A/C Off, place the transmission in Drive, and disconnect and plug the vacuum advance hose at the distributor.
  4.  

If instructions on car's underhood sticker differ from these, follow underhood sticker.

  1. Set the ignition timing, if necessary.
  2.  
  3. Reconnect the vacuum advance hose.
  4.  
  5. Disconnect the purge hose at the vapor canister.
  6.  
  7. On cars without A/C: set the idle speed by turning the idle screw to obtain the specified rpm. On cars with A/C: set the idle speed screw to the specified rpm. Turn the A/C on. Open the throttle momentarily to extend the solenoid plunger, then adjust the solenoid screw to obtain the solenoid idle speed shown on the underhood sticker. Turn the A/C off.
  8.  
  9. Connect all hoses, and remove the tachometer.
  10.  

1978-80 M4MC-M4ME Carburetor

  1. Run the engine to normal operating temperature.
  2.  
  3. Make sure that the choke is fully opened, turn the A/C Off, set the parking brake and block the wheels.
  4.  
  5. Connect a tachometer to the engine according to the manufacturer's instructions.
  6.  
  7. Disconnect the purge hose from the vapor canister. On the 350, plug the purge hose.
  8.  
  9. Disconnect and plug the EGR vacuum hose at the valve. Disconnect and plug the vacuum advance hose.
  10.  
  11. Place the transmission in Park.
  12.  
  13. Check and adjust the timing.
  14.  
  15. Reconnect the vacuum advance hose.
  16.  
  17. Place the transmission in Drive.
  18.  

If instructions on the underhood sticker differ from these, follow underhood sticker.

  1. On cars without A/C: Turn the idle speed screw to obtain the specified rpm.
  2.  

On cars with A/C: Turn the idle speed screw to set the specified curb idle speed. Turn the A/C ON and disconnect the compressor clutch wire. Open the throttle momentarily to extend the solenoid plunger. Adjust the solenoid screw to obtain the solenoid idle speed shown on the underhood sticker. Reconnect the compressor clutch and turn the A/C Off.

  1. Reconnect all hoses and remove the tachometer.
  2.  

1981 & Later

Most 1981 and later models are equipped with an Idle Speed Control (ISC) mounted on the float bowl. Idle speeds are computer controlled and the ICS should not be adjusted.

On some V8 models an Idle Load Compensator (ILC) is mounted on the float bowl to control the curb idle speed. The ILC is adjusted at the factory and capped to prevent readjustment. If an idle problem is suspected on either of the above systems it is recommended that it be corrected by a qualified technician on cars that do not include either an ISC or ILC, but are equipped with air conditioning, an idle speed solenoid is used to maintain idle speed. For adjustment of these models refer to the 1978-80 adjustment procedures.



Click image to see an enlarged view

Fig. Fig. 1: Common 2 bbl idle speed adjustment locations

The underhood sticker specifies which idle system your car is equipped with.



Click image to see an enlarged view

Fig. Fig. 2: Common 4bbl idle speed adjustment locations

 
label.common.footer.alt.autozoneLogo