Idle Speed: Adjustments

1. Run engine until vehicle reaches normal operating temperature, push the cold start cable all the way in, and turn all electrical accessories off.
2. Mount sensor (VW 1324, or equivalent), on valve cover (magnetic end). Since diesel engines do not need spark ignition systems, RPM signals are generated through this vibration sensor.
3. Connect tachometer positive cable to sensor post and tachometer negative cable to ground sensor cables to battery posts.
4. Idle speed indicated on tachometer should be 950 ± 50 RPM.
5. Adjust, if necessary. Loosen locknut, turn IN to raise idle speed or turn OUT to lower idle speed, then tighten locknut.
6. Now accelerate engine briefly to "full load" position. Engine speed should be between 5300 and 5400 RPM for naturally aspirated engines and 5100 ± 50 RPM for turbocharged engines.
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7. Adjust, if necessary. Loosen locknut, first turn OUT to raise maximum speed or turn IN to lower maximum speed, then tighten locknut. If maximum speed is set too low, the engine will not produce full power. If maximum speed is set too high, the engine and injection pump can be damaged by over revving of the engine.
8. Adjust any linkages (accelerator, cruise control) affected by engine speed adjustment as needed.