Boost Pressure Limiting Valve
The wastegate valve operates on the opposite principle to conventional wastegate valves. When there is no control pressure, the wastegate valve limits the wastegate pressure. Make sure the connections between the vacuum pump and the wastegate valve are tight.
Checking the calibration pressure
Use a magnetic support with a pointer type indicator that is mounted on the end of the pressure regulator stem (maximum possible along the axis of the pressure regulator rod). Smoothly create a vacuum in the boost pressure limiting valve using the device with pressure gauge Mot. 1014 (Fig. 3.57).
Fig. 3.57. Checking the calibration pressure.
Adjustment on the car
When checking the calibration pressure, it may be necessary to additionally adjust the length of the boost pressure limiting valve stem A (when the pressure goes beyond the tolerance limits) (fig.3.58) . Loosen lock nut 1. Adjust by tightening or loosening adjusting sleeve 2 by half a turn until the correct calibration pressure is obtained. After tightening lock nut 1, check the calibration pressure.
Fig. 3.58. Adjusting the calibration pressure.
Check the adjustment result during a road test by monitoring the parameters «Boost Pressure Limiting Valve Cyclic Opening Ratio» and «Boost pressure» using diagnostic devices.
Calibration values
| Vacuum value, mbar | Rod travel, mm |
| 120 | 1-4 |
| 400 | 10-12 |
| > 450 | The rod is in the extreme position |
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