GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

Diesel Engines

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IDLE ADJUSTMENT



See Figures 1 and 2

Adjustments to diesel fuel injection units are to be performed only in the case of parts replacement on the injection unit.

The following procedure requires the use of a special tool.

  1. Apply the parking brake, place the transmission selector lever in Park and block the drive wheels.
  2.  
  3. Start engine and allow it to run until warm, usually 10-15 minutes.
  4.  

Failure to have the engine fully warmed up will result in sooting of the probe which will cause an incorrect reading and adjustment for the timing.

  1. Shut off the engine, and remove the air cleaner assembly. Install the cover tool J-26996-1. Make sure the EGR hose is disconnected.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: Cover - Tool # J-26996-1

  1. Clean the front cover RPM counter (probe holder) and the crankshaft balancer rim.
  2.  
  3. Clean the both ends of the glow plug probe and the lens to the photo-electric pick-up. Scrape the carbon from the combustion chamber side of the glow plug probe. Look thorough the probe to make sure it is clean. Retarded readings will be obtained if the probe is not clean.
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  5. Install the magnetic pick-up probe of tool J-26925 fully into the rpm counter. Connect the battery leads; red to positive (+) and black to negative (&ndash).
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Tachometer tool # J-26925 for a diesel engine

  1. Disconnect the two-lead connector at the generator.
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  3. Turn off all electrical accessories.
  4.  
  5. Allow no one to touch either the steering wheel or service brake pedal.
  6.  
  7. Start the engine and place the transmission selector lever in D (Drive).
  8.  
  9. Check the slow idle speed reading against the one given on the underhood emission control sticker. Reset if required.
  10.  
  11. Unplug the connector from the fast idle cold advance (engine temp.) switch and install a jumper between the connector terminals. Do not allow the jumper to touch ground.
  12.  
  13. Check the fast idle solenoid speed against the one given on the underhood sticker and reset if required.
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  15. Remove the jumper and reconnect the connector to the temperature switch.
  16.  
  17. Recheck and reset the slow idle speed if necessary.
  18.  
  19. Shut off the engine.
  20.  
  21. Reconnect the lead at the generator.
  22.  
  23. Disconnect and remove the tachometer.
  24.  
  25. If equipped with cruise control, adjust the servo throttle cable to minimum slack then install the clip on the servo stud.
  26.  

 
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