Boost pressure control on the Vito V230 (pre-chamber engine)

Hi,

I currently have a V230 (not yet with CDI) in the workshop where the turbocharger boost pressure control is not working.

Regarding the system: It's a pre-chamber engine with a turbocharger equipped with a wastegate. The wastegate is controlled by vacuum (similar to the VTG system used by VAG), and there's a type of "N75" valve, which is a boost pressure control solenoid valve. I have already replaced the "N75" valve.

If I bypass the magnetic valve and control the wastegate directly with vacuum pressure, it builds boost pressure, but unregulated – so the turbo is working correctly.

It's a mechanical inline injection pump with integrated LDA (Low-Pressure Accumulator), and there is a turbocharger pressure sensor (three-pin).



Does anyone have any advice or a wiring diagram that shows how the boost pressure control system is connected to the EGR valve, bypass valve, and mass airflow sensor?

Greetings.
John.

Is the hose to the MAP sensor free of oil (sludge)? I once had this problem with an AHU engine. It prevented proper boost pressure regulation due to blockage.

Best regards.

As far as I know, the OM601 turbocharged diesel engine functions in the same way as the 602 and 603 engines.
Specifically, the wastegate is activated by overpressure using a motor overload relay, which you probably confuse with the N75 valve. This valve opens the pressure hose to the ALDA (actuator) when the boost pressure is too high.
If the sensor is now clogged with EGR sludge, it will get stuck in the open position.
You can easily bypass this protection device by connecting a hose from the intake manifold to the ALDA (air leak detection apparatus).

No, unfortunately - the system operates under negative pressure, similar to the early dCi engines from Renault. Atmospheric pressure at the canister causes the wastegate to open.

If I bypass the N75 valve, which applies vacuum to the actuator, the wastegate closes. Even at idle, some pressure builds up (you can feel it on the charge air hose).

I disconnected the pressure sensor on the pneumatic side and even applied a vacuum to it once. It makes absolutely no difference.

My current assumption is that the control unit for turbocharger pressure regulation, ARF (Anti-Roll Function), and the shut-off valve are not receiving power, as the other systems are also not functioning.

Have you ever checked the vacuum sensor diaphragm for cracks using a syringe? It's possible that's the issue. The PWM signal from the valve might not be working correctly due to a potential defect. Best regards.

Quote:

Hast Du die Unterdruckdose mal mit ner Spritze auf Membranrisse untersucht? Wäre denkbar.. Der PWM-Signalverlauf des Ventils kommt vielleicht aufgrund eines ggf. bestehenden Defektes nicht mit der Situation klar.

Yes, but unfortunately that's okay... The problem definitely lies with the control of the N75 valve.

Ich finde die Ansteuerung mit Unterdruck bei einem Wastegatelader zwar auch etwas seltsam, aber aufgrund Deiner nachweislichen Erfahrung im Forum schließe ich dies aus.. Denkbar ist aufgrund von Abgasreglements diese Lösung vom OEM. Ka doubt...

Are there any new findings regarding this? Has the signal been captured using an oscilloscope? Best regards.