boost problem :O/

[cabrio boy]

after reading alot on here i decided to fit a catch can as i was loosing boost thought by deleting the pcv system it would fix my boost problems , ive new maf new n75 valve full samcos new recirc valve but i still have neg 20 on my boost gauge and im only boosting to 6-7 psi any ideas people imalmost out of faith on this car ,

no fault codes when plugged in

going to pressure test it tomorrow what the best pipes to do this on ????????

any ideas ??? i know there is a leek cause of the -20 on my boost gauge ???

 

[Dani_B19]

Whos told you -20 is a boost leak, thats what it should be, anything under -16 so is a leak, a typical 1.8t should be -18/20. Regarding boost thats about for a a3 150bhp, that is me guessig its a a3 as youve not stated what car it is?

 

[cabrio boy]

s3 2002 remapped few other bits , new to audis just by other cars ive owned on a psi boost gauge they have always been -10 when on idle on the gauge this is -20 , also im only boosting to 6 psi any ideas ?

 

[s3dave]

Firstly its not a Boost leak if its -10 - -20 in HG at idle your engine is in vacuum, there is no boost at that stage...
i would say that -20 in hg is normal, so the vacuum pipes should be ok.

 

[badger5]

OP: ignore vacuum.. boost is what you are missing.
Its running on actuator pressure only.... for some reason.. be it N75 plumbed wrong, broken etc etc

 

[Dani_B19]

Argh, so as said the boost is defo down, when my n75 was the wrong way round i was only making actuator pressure, check that as bill said!

 

[cabrio boy]

right had a few hours this morning before a job , reading alot last night i did a few tests run it up the road with the n75 unplugged so actuator pressure only it runs 2-3 psi on my gauge with n75 plugged back in 5-6 psi , i can see there is a massive fault now since ive had the car its been everything that could go wrong can but it wont beat me lol , actuator next ? boost feels strong but iknow its got an apr remap by awsome so should be a fair wack more than that surly ????

 

[s3dave]

Sounds like a weak/leaking Actuator....

 

[Welly]

Agree with Dave, 2-3 PSI actuator pressure is poor. Has the actuator been tinkered with at all?

 

[cabrio boy]

anyone got a picture of there n75 valve so i can just make sure thats correct googled it no pics

 

[Welly]

anyone got a picture of there n75 valve so i can just make sure thats correct googled it no pics

No, but I can tell you...

There are three stubs in a T pattern on the N75 yes?

One is longer than the others. This one goes into the TIP. From there, the one that is horizontal is for the feed from the charge pipe, and the one at the top is the actuator outlet.

 

[cabrio boy]

i dont know i bought it thinking it had great history from awsome and it seems to me guy before didnt do things properly think owner before him used awsome and he just abused it and now im putting it all right owned the car 8 months and never had the full power out of it ive had damaged pipes n75 valves alsorts grrrrrrrrrrr but it seems joys of owning an s3 lol just want it running right now !

for ages it run 1 day at 6 psi the following day at 12 then just went off to 6 psi permanant its strong and holds the power doesnt back off now ive fitted the catch can and new n75 valve new maf new recirc it is a perfect 6 psi no more

 

[Custom-Code HQ]

Have you done any VAG-Com logs to see if you have a faulty boost gauge?

 

[s3dave]

http://s4wiki.com/images/d/d1/N75.jpg

 

[badger5]

i dont know i bought it thinking it had great history from awsome and it seems to me guy before didnt do things properly think owner before him used awsome and he just abused it and now im putting it all right owned the car 8 months and never had the full power out of it ive had damaged pipes n75 valves alsorts grrrrrrrrrrr but it seems joys of owning an s3 lol just want it running right now !

for ages it run 1 day at 6 psi the following day at 12 then just went off to 6 psi permanant its strong and holds the power doesnt back off now ive fitted the catch can and new n75 valve new maf new recirc it is a perfect 6 psi no more

5-6psi is actuator, 12psi is std..... You sure its remapped?

 

[cabrio boy]

yes have all the paperwork from awsome, done an air test on it tonight found one of the intercooler samcos leeking feels alot stronger now thats fixed but still 5.5 psi thats with it plugged it in to vag . com i do think its the actuator now only thing left lol

 

[cabrio boy]

as ive found leeks its moved further along in different parts a few times ive done bits and had it for a few hours running 19 , 20 psi but then following morning go out and its found its self another leek , ive deleted the pcv now and fitted a catch can and replaced all vacume hoses so it seems to have crept along the system to the actuator 6 months of owning this car it wont beat me it will be rolling roaded at its full power lol