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There are description deal with N75 valve (VAG No. 078 906 283 B) fitted in 2.7 BiTurbo engines.

For first, a small background why I decided to "take care" about that valve.
There were a lot of presure overboost occurance pushing ECU in LIMP mode - resulting in almost complete disappearance of boost and power ;-(.  I have done a bit of reading and find out, that the most possible reason for such behavior is the N75 valve, more precisely, dirt inside it - so it needed cleaning ;-).
Unfortunately, the cleaning attempts with various types of cleaners not yielded the desired result, so I decided to "go for broke" and "spoil" the valve - buying a new one could be the wors case ;-).

Below "photographic documentation" from the destruction/repair process:


It turned out, that the N75 valve consist of two main parts - a coil and a three output hoses adapter. After disassembling N75 valve can be easily take into pices shown in the picture above.

Further disassembling and cleaning of every components was child's play ;-)

A brief explanation about element on the picture below:

As you can see, this item in the valve is regulated - you can get access to it from the top of the valve. The screw on the standard valve is 'glued' in the position it was calibrated in the factory, if you want to tweak it, do it when the car has been for a good run and the valve is hot - makes the screw easier to turn, or use small gas torch to warm it up. This way we can obtain regulated N75 valve ;-) .
After everything described above it was enough to have everything put together back, glue and mount in auto.

Performing the above steps "groping" contributed to the fact, that the valve is now a little "fouled" in terms of aesthetics - the next will go much better ;-)

After installing valve in car test drive and adjust the valve time came. The valve is very sensitive to regulation - for one screw turn only regulation state change from underboost ( the desired charge presure can not be achieved - approximately 200 mbar missing) to pressure oscillations around desired value state. Currently I obtained regulation state, where after the momentary peak, presure nicely holds desired setpoint.

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