S320 CDI EGR question?

paulkno

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S-Class W220 2002 320CDI
The EGR valve is vacuum operated. With the vacuum transducer disconnected is the valve opened or closed?

I recently removed and cleaned the inlet manifold and I do not wish to repeat this so I'm looking into disabling the EGR. I purchased a wiring kit to disable it electronically by tapping into the the MAF and transducer wiring and disconnecting the transducer fooling the ECU into thinking the EGR is still functioning.

However... If I disconnect the vacuum I have EGR jammed open symptoms and the engine is audibly slightly louder like the valve is open allowing exhaust gases into the inlet. With the vacuum connected the engine is quiet and full power is restored. Leading me to believe that the vacuum operated actuator is closing the valve. So disconnecting the transducer and fooling the ECU into thinking the transducer is still connected is redundant as the EGR valve will be constantly open.

The only instructions available for this show a W210 CDI which has a slightly different EGR arrangement to the W220. Has anyone successfully bypassed the EGR on an S-class and have a clue what I'm talking about?
 
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paulkno

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S-Class W220 2002 320CDI
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Update..

The EGR valve's natural state is open. The vacuum is used to close it.

So the wiring cheats to bypass the transducer and keep the ECU happy don't work on the W220 S320 CDI's. Bypassing the transducer results in the usual loss of power. The car drives great while setting off and at low speeds but has no power if you want to accelerate or overtake.

So I tried an experiment. I removed the actuator and fitted a spacer between the actuator and valve. This allowed the actuator to continue operating but keeps the valve closed all times. The results were interesting. The opposite of when the valve is jammed open. I'm assuming this is due to the mapping for airflow and manifold pressures for an EGR valve that is supposed to be open. As far as I can see you cannot DIY the EGR valve to be permanently closed on an W220 CDI (unless you have a later electronically controlled one maybe).
 

Taffy7hfa

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2004 ML350 Inspiration .2002 ML270 CDI .2016 Hyundai i30 1.6crdi.2014 Peugeot 308 1.6 HDI.
Don't bother.. your egr is there for a reason, to modify your car so that it throws out even more nox is really not a good idea, also next month MOT's are changing and your MOT inspector will be checking that your cars original emissions equipment is present and un-modified.
 
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