N75 valve

[paulrom]

hi all meagain i am trying to source a new N75 for my 200 b5 s4 as it is playing about and i am getting anhythin from 5psi to 12psi pending on how the valve feels


anyone got any idea's or is this a dealer part only ????

 

[andybnwc]

are you sure its the n75 , have you pressure tested it vag comd it etc ?

 

[mac1403]

I would be more tempted to check the diverter valves first and pressure test.

 

[aragorn]

5psi is the actuators default pressure, so from the breif outline you've given there, it would follow that its an N75 issue.

I would however concur with the other opinons that you should get the induction system pressure tested, and also replace the dumpvalves.

N75 is dealer only, and is around 45quid iirc
Dump Valves are about 20quid each and i'd advise fitting the 710N version from the Audi TT

It will cost you about 50quid or so to get a garage to do a health check including the pressure test iirc.

 

[paulrom]

forge alloy recircs fitted when i bought the car and i know ther ok and have just last weekend fitted the new silicone boost hoses and have pressure tested it myself so i know there sound

havn't vagg'd it yet as can't get my ebay purchased one to work
but still recon on it beingthe N75 ??????
is there any way to check the valve i.e voltage/resistance etc or has it got to be vag'd

second ly can u post up a description of where it is on the b5 as i havn't got a clue LOL where it is still getting to know this car as i am an ex cossie and then renauolt turbo convert

 

[andybnwc]

just under that left cover

 

[andybnwc]

how did you do the presure test

 

[paulrom]

took off the air intake flex at the rear of the y air intake and put on a homemade rigg (bearing in mind i'm a pipe fitter/plumber for a living) that wasn't to hard it looks very simular to the one's 4 sale on ebay

and pumped it up to around 1 bar and left it foraround 25mins no drop

 

[andybnwc]

25mins ! must be no leaks ,try disconnect the n75 valve see what happens to boost then , still a good idea to vag it . ive had so many problems with going into limp.

 

[paulrom]

lmao yerrr slight typo there 5mins m8 was meant to say LOL

the boost changes as you drive it put your foot down to come on boost and it'll give you say 7psi then ease off and do the same again after say stopping at a set of lights and it'll give you 11-12 psi and so on and so forth no regularity to it

 

[S4twiggy]

im new to my S4 B5 so dnt know that much about them at the moment so was wondering wot a N75 valve was? im looking to learn about my car so need advice from you boys who know wot your on about. excuse my ignorance

 

[aragorn]

N75 controls the boost, by bleeding off boost pressure the actuators can see. Its basically an electronic bleed valve, just like the amal valve used on cosworths.

Without the N75 the car would just run 5psi, and thats what you will see with the N75 unplugged.

You really need to get a vagcom kit, its invaluable for cars like the S4 as you can monitor the engine data etc closely to see whats happening. Ebay lead for £10 plus a full version of the software is the cheapest route.

 

[Blue_Thunder]

Does sounds like an N75 issue. There's no easy way to test it really, so swapping it out for a good one is your best option. Disconnecting it will just mean your car isn't boosting beyond the 5psi or so it takes until the wastegate springs are forced open, so it won't prove anything.

It's the valve with the brown plastic connector just infront/below the accordian pipe. Can't miss it with the engine cover off.

 

[andybnwc]

its soft limp mode , could be anything the n75 when shown a fault drops the boost too 5psi , really do need vagcom , where abouts are you

 

[paulrom]

right i'm pretty much decided it needs the n75 changing as have spoken to a m8 of mine and his s4 was doin the same thing last month and changed the valve and all sorted

is this a dealership only part or can i source it from GSF or euro carparts ?????

 

[aragorn]

speak to Siena on here, he should be able to do you a decent price on it.

 

[Lee Goodall]

Is it an 'F' valve on the S4?

 

[aragorn]

from vagcat: 078906283B

Seems its only used on the 2.7T, RS4 and RS6

 

[Lee Goodall]

Oh ok.. I've not got one of them!

Got an almost new 058 906 283 F if anyone needs one though.