Help With N75 Valve - 1.8T

tgorman

LCR = 285Bhp + 330Ft.lbs
Jul 22, 2009
91
0
tried to adjust the n75 to get the boost to come in smoother ,but it sent my car into limp mode (wasnt going over 0.5bar and hard to gte over 4k revs )

i then put the valve back to normal but it still didnt work so i just though i would have a go with it backwards and the car worked perfect boost was kicking in quicker than before

but then the next day on the motorway it went back into limp mode ,i then put the valve the normal way around and reset the ecu and erased any fault codes but was still in limp mode

then put it back on backwards and the car works fine again but the car will properly go into limp mode again soon

Can Anyone Help ?

thanks
 

DannyC87

Rubbing is Racing :-)
Mar 4, 2008
3,459
0
Are you sure what you are reffering to as backwards isn't forwards?? Check the orientation of this as I know of a member on here that bought a car with the n75 fitted backwards, this led to the turbo over-boosting and the engine going pop!
 

tgorman

LCR = 285Bhp + 330Ft.lbs
Jul 22, 2009
91
0
no it was definaltly forwards before and now will only work for a while backwards
 

DannyC87

Rubbing is Racing :-)
Mar 4, 2008
3,459
0
very strange, n75 valves have a specific orientation and should not work backwards. The reason it is boosting properly is because the n75 can't send any pressure to the wastegate to tell it to open when it is fitted in reverse; this also means it can't limit the boost at all; not good! What fault codes did you have to reset? Sounds to me like limp mode is being triggered by something else and by reversing the n75 you are not letting the ecu control boost - ie not letting limp mode occur!
 

tgorman

LCR = 285Bhp + 330Ft.lbs
Jul 22, 2009
91
0
when backwards the boost has been exactly the same as it was orginally
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
N75 has three pipes attached to it. Forwards and backwards have little meaning in these circumstances. Begin by posting pictures of both installations, with each pipe clearly labelled.

I wasn't aware that the N75 was adjustable. What have you done to it? Is it possible that you have broken it, hence the odd behaviour?
 

Pabs

Active Member
May 3, 2004
5,936
4
Basingstoke
Few pointers about the N75 screw, as I had a play with mine on a spare one I had:

Usually, it is thread-locked in place. Chances are if yours is, you'll just damage it.

Adjustment of the screw is MINISCULE. (The max movement I could get on mine was less than 1/4 of a turn, and at either extreme the car didn't run well at all)

The ECU map is written to control the N75 - and it expects how the N75 will react. If you alter this too much - the ECU will not get the results it expects and will constantly try to adapt, giving bad results, or worse, limp mode.

N75 is designed to work only in 1 orientation. This link will help:
http://forums.audiworld.com/showthread.php?t=1476692

If you rotate the valve, god knows what will happen - I certainly wouldn't like to try it!
 

tgorman

LCR = 285Bhp + 330Ft.lbs
Jul 22, 2009
91
0
thanks for the help guys i should be getting a n75 in the post today i can try out to see if my current one is broken
 
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