N75 advice which one to get N75J or N75K

20VT_AUQ

Roar
Dec 5, 2019
60
29
Hey all

I have a 1.8T AUQ (180hp) with k03s turbo and my N75 is faulty and I am trying to guess which would be the best option for my engine.

I plan to do a stage 2 remap to maximize what our tiny turbo can bring :D

As far as I know stock N75 is the N75C although nowadays its been replaced by the N75F which is nearly the same.

Then we have the N75J which is largely recommended by Audi communities and the "rare" N75K that seems to be even better.

I heard terror stories about the N75H and how it brings you into limp mode.

Anyone has experience with the J or K valves? They any good for the AUQ?
 

Connor H

Active Member
Dec 19, 2019
1,014
498
Essex
I recently had my N75 changed during a remap, although i have no idea what one they put in, all i know it was the a recent revision genuine audi n75. All i can say is the genuine ones are the only one to go for!
 
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20VT_AUQ

Roar
Dec 5, 2019
60
29
I recently had my N75 changed during a remap, although i have no idea what one they put in, all i know it was the a recent revision genuine audi n75. All i can say is the genuine ones are the only one to go for!
Probably a N75J then

You can see the reference number, they all the same except the last letter.

I.e. 034906283J or 034906283F, etc
 

oggydoodaa

Active Member
Dec 13, 2015
76
18
30
Basingstoke
if anyone can let me know a ballpark figure for an n75 replacement as I'm pretty sure mine is going/gone, the car (1.8 20VT AUQ ) keeps boosting on acceleration but then immediately dumping the boost, like the dump valve is stuck open, I know its not the valve as its a 007p and I serviced it 3 months ago (new spring + grease etc) all genuine Forge parts. If I floor the pedal it boosts but I don't feel like its the correct psi feels a little slow to get going, I don't have a boost gauge either, could I just run vcds and drive round fast and furious style with laptop on seat would that show me? I have a warning code for a pressure drop between turbo and DV so wandering if its the n75?
 

Connor H

Active Member
Dec 19, 2019
1,014
498
Essex
if anyone can let me know a ballpark figure for an n75 replacement as I'm pretty sure mine is going/gone, the car (1.8 20VT AUQ ) keeps boosting on acceleration but then immediately dumping the boost, like the dump valve is stuck open, I know its not the valve as its a 007p and I serviced it 3 months ago (new spring + grease etc) all genuine Forge parts. If I floor the pedal it boosts but I don't feel like its the correct psi feels a little slow to get going, I don't have a boost gauge either, could I just run vcds and drive round fast and furious style with laptop on seat would that show me? I have a warning code for a pressure drop between turbo and DV so wandering if its the n75?
Pressure drop is usually a boost leak somewhere, but it could be anywhere. Check all your PCV, EVAP, SAI, N249 etc... whatever you have left.

Check intercooler hoses, and hoses from the turbo to the intercooler (will require getting underneath)

I found a couple of small leaks one on a clamp on my PCV check valve (under the mani) and another a random evap system hose. Tiny tiny leaks but got rid of my phantom pressure drop code.

Obviously check your dump valve hoses etc.

If it was your n75 you'd have weird boost behaviour (up and down) and a different code

I would get a boost gauge unless you can get someone to watch your boost psi requested vs actual while you drive
 
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20VT_AUQ

Roar
Dec 5, 2019
60
29
if anyone can let me know a ballpark figure for an n75 replacement as I'm pretty sure mine is going/gone, the car (1.8 20VT AUQ ) keeps boosting on acceleration but then immediately dumping the boost, like the dump valve is stuck open, I know its not the valve as its a 007p and I serviced it 3 months ago (new spring + grease etc) all genuine Forge parts. If I floor the pedal it boosts but I don't feel like its the correct psi feels a little slow to get going, I don't have a boost gauge either, could I just run vcds and drive round fast and furious style with laptop on seat would that show me? I have a warning code for a pressure drop between turbo and DV so wandering if its the n75?
Sounds like some hose(s) is/are leaking, check them out. I am upgrading them all with silicone hoses by SFS
 
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