Maximum Engine Speed, Checking and Adjusting
MAXIMUM ENGINE SPEED (RPM), CHECKING AND ADJUSTING
Checking/adjusting conditions
- Minimum oil temperature 60 °C (140 °F).
- Cold start accelerator cable must not be pulled
- All electrical consumers switched OFF
Engine speed (RPM) can be measured using the VAG 1367 engine tester with TDC sensor or adapter VW 1324.
1 - Idle speed adjusting screw
2 - Maximum engine speed (RPM) adjusting screw
3 - Stop screw for minimum idle speed
4 - Stop screw for maximum idle speed (idle speed boost)
5 - Residual fuel volume adjusting screw
Idle speed
Idle speed is adjusted by turning the idle speed adjusting screw -1-.
Specification: 900 ± 30 RPM
Idle speed boost
- Pulling the Cold Start Accelerator cable to the first stage increases engine speed by approx. 60 RPM.
- When the cable is pulled out to its maximum, engine speed must rise to 1050 ± 50 RPM.
NOTE:
The manufacturer's basic setting for the diesel injection pump ensures that idle speed can normally be adjusted as described, and that the higher idle speed specified above can be reached by pulling out the Cold Start Accelerator cable. If the idle speed cannot be adjusted as described, carry out the basic adjustment see above.
Idling speed adjustment
If idle speed cannot be adjusted to less than 930 RPM by turning adjusting screw -1- because stop screw -3- is touching the stop:
- Loosen lock nut on stop screw -3- for minimum idle speed and turn screw out.
- Using adjusting screw -1- set idle speed to 900 RPM by turning linkage.
- Thread stop screw in until it makes contact with minimum idle speed stop, then tighten lock nut.
Idle speed boost adjustment
If there is a deviation from the specified engine speed (1050 ± 50 RPM) when the Cold Start Accelerator cable has been pulled all the way out:
- Loosen lock nut on stop screw -4- for maximum idle speed and, with the Cold Start Accelerator cable pulled fully out, adjust fast idle to 1050 RPM by turning the stop screw -4-.
- Tighten stop screw lock nut.
Maximum engine speed (free running)
- Accelerate to Wide Open Throttle (WOT) and set maximum engine speed with adjusting screw -2-.
- Specification: 5200 ± 100 RPM
- Lock adjusting screw.
Residual fuel delivery adjusting screw
The residual fuel delivery adjusting screw -5- is secured with an anti-tampering cap and its setting must not normally be altered.
The so-called residual fuel delivery is adjusted on a test bench by the manufacturer, using this screw.
If the screw setting has been altered, this may result in the following problems:
- Screw turned in = residual fuel delivery too large. In this case, engine speed increases and it is not possible to set idle speed.
- Screw turned out (idle travel to control lever) = residual fuel delivery too small. This causes performance problems such as a "flat spot" when starting from rest and accelerating from low revs, or jerking in all gears.
If such problems occur, the following basic setting must be carried out at the residual fuel delivery adjusting screw -5-.
- Remove anti-tampering cap.
- Release lock nut for adjusting screw -5-.
Residual fuel delivery too small:
(performance faults):
- Turn adjusting screw in just until idle speed increases.
- Turn adjusting screw back one-half turn from point at which idle speed increases.
- Lock adjusting screw and secure with new anti-tampering cap.
Residual fuel delivery too large:
(engine speed too high):
- Turn adjusting screw out until engine speed no longer drops.
- Turn adjusting screw in again until idle speed rises.
- Turn adjusting screw back one-half turn from point at which idle speed increases.
- Lock adjusting screw and secure with new anti-tampering cap.