Testing is to be carried out with the HHT
The irregular running screen is located under the actuations menu
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CDI Actuations
1 Idle speed control
2 Exhaust gas recirculation
3 Boost pressure control
4 Irregular running
5 Compression test
6 Suction fan
7 Element shutoff
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Before starting this actuation, the cylinder-specific quantity injected for the smooth operation correction (see HHT, actual values, check idle position) are to be read out. This actuation is only necessary if the maximum correction (+4.5 ME) has been reached in one or more cylinders.
Notes on HHT diagnosis, CDI smooth running correction
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Irregular running test
The irregular running test must be carried out at idle when the vehicle is stationary. If the maximum correction (+ 4.5 ME) has been reached in one cylinder, the speed must be checked. If this is significantly less than the speed of the previous cylinder, there is a fault in the corresponding injector.
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HHT mask
Correct pattern Irregular running
Shown on engine 611
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CDI Actuations
Cylinder
1 - 4000 rpm
3 - 4000 rpm
4 - 4000 rpm
2 - 4000 rpm
Engine speed
750 1 rpm
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HHT mask
Rejection pattern irregular operation
Shown on engine 611
Fault on cylinder 2
CDI Actuations
Cylinder
1 - 4000 rpm
3 - 4000 rpm
4 - 4000 rpm
2 - 4000 rpm
Engine speed
759 1 rpm
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