what the hell have i got here!?!? help!

limbo118118

limbo118118

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rite... i bought my s3 an it had some sort of MBC... from a pipe coming off the turbo and then connected to the littl sensor (brown) by the TIP... well it didnt work anyways, an i wanted to get rid!... iv recently done the n249 bypass also.

so i removed it an then my car went weird an was boosting to like 23psi an sometime 5..

so i quickly went out a bought a new MBC

i looked up how to fit it i saw it ideally wanted to be put in parallel? with the n249.. but i had already removed all of that and just left it electronicly connected, so that wouldnt work for me..

so now im ended up with this....see pics..

an for some reason my forge 007p sounds completly different its now ''tinging'' when dumping
iv read up an people say you can reverse them.. but i didnt even touch mine!?


please help someone! ideally i know i want to get rid of the MBC! just i dont have a clue about this stuff im lost now! :s

before....
IMAG0227-1.jpg



now...
IMG_0193.jpg
 
You need to bin all the stuff other than the N75 (brown sensor which is actually a valve...)

Bin the brown valve too as its a J valve and replace it with the proper black one (F valve from memory)... J valves are spikey boost wise and tend to put the ECU into limp mode (0.5bar)

Then plumb in as follows... of the 3 outlets on the N75 the longest one goes into the TIP... the opposite outlet to that goes to the actuator (turbo) and the one at the bottom connects to the charge pipe...

I suspect it was all fitted to attempt to get more boost after a remap... the ECU keeps going into limp mode as the boost deviation is too great hence why you have 23psi one day and 5psi the next...

Pikey++ mod I'm afraid and can be damaging to the engine if not done right...

<tuffty/>
 
APY engines do not seem to mind the J valve, i have had mine on a couple of years and its been fine...
I would pipe the N75 valve in correctly , doing away with the MBC/T pieces as said, and see how it runs...
 
rite i plumbed it all in like you said tuffty an now its boosting weirdly like it goes to 14psi then dies off then goes back up.
an then another time it went to 15psi an held all the way thru the rev range, was really doing some werid stuff!? could i have a faulty n75???? worth replacing to the black one?

also the dump vavle is still making a 'ting' noise, i took it all apart it has a green spring. but still dont have a clue why its playing up!? any ideas???
 
limbo118118 said:
can i bypass the n75??
Click to expand...

No.... Or yes arguably if using an MBC or EBC but there is no reason to... I suspect you have other problems...

Is the car actually remapped?... stage 1 boost is around 17psi typically... need to check fault codes and maybe do some logging...

Have you plumbed the N75 the right way around?

<tuffty/>
 
no its not remapped yet. i think my best bet for now is too bypass the n75 with using a mbc if i can!? because i think theres somthink broke with mine :s an yeh i put it the right way hah

any idea how i remove it an plumb in the mbc correctly? cheers
 
Cant you borrow a n75 off anyone to try? Using a MBC because it is not running right is not a good practice to be fair, there could possibly be underlying issues and your gonna end up chasing your tail....
 
limbo118118 said:
no its not remapped yet. i think my best bet for now is too bypass the n75 with using a mbc if i can!? because i think theres somthink broke with mine :s an yeh i put it the right way hah

any idea how i remove it an plumb in the mbc correctly? cheers
Click to expand...

Well there is your main problem right there!!!

If its not mapped then you cannot run more than factory boost... the ECU is hitting limp mode all the time!!

Get the N75 replaced with the correct version, make sure the pipes are connected correctly then if you want more power get it mapped...

Please let this be a lesson to anyone contemplating pikey methods of gaining boost...

I would unplug the N75 electrically until you get the above done... end...

<tuffty/>
 
Ok thanks alot for your help mate, so with havin the mbc an the n75 electricaly connected now sends it to limp an then removing the n75 lets just the mbc run standard psi!? Just trying to understand this abit more :)
 
Sorta... bin the MBC... what you have is a bleed valve and is crap... connect the N75 as I described and assuming nothing else is wrong then it 'should' run ok... std boost is 12psi... any more then you have a problem... most likely the J valve... especially as the car is not mapped...

If you are still experiencing issues then disconnecting the N75 electrically (not removing it or replacing it with the mbc...) will let the turbo run on actuator pressure (7psi) until you can take it to a specialist to have it looked over...

Forget using the mbc, change the J valve to a std one and it should all work fine again... then get a map... you could get it mapped with the J valve if need be but tbh it won't make that much difference and would need a custom stage 1 from the likes of Badger 5 or R-Tech as the spiky nature of the J valve will still need to be dealt with in the mapping... std stage 1/2 maps are designed around std hardware not pikey tuning add ons...

So you understand... the map is expecting to create no more than 12psi... it has built in protection in case of issues that could cause the turbo to produce more boost than the std map is ready for... this is what is happening with yours... the ECU sees more boost than its asked for and considers this a problem so it goes into limp mode... the fact that you are seeing 5psi at all suggests that the N75 is plumbed correctly... its the mbc thats causing your pain... bin it... bin it now...

<tuffty/>
 
<tuffty/> said:
Doesn't make it right....

<tuffty/>
Click to expand...

:think: Doesn't make it wrong either, Narrow band cars seem happy with the valve, ive had mine since i got my car, and before that on mk4 golfs, from what i understand they are of a higher frequency that operates faster than a standard valve, and as the OP as an APY i dont think it will be the Valve causing his issues...as while they are quicker at getting to requested they should not over boost from requested..wasnt it fitted to the TT 225 as standard with no issues?
It would be interesting to see how it reacts on a BT it might get you off the line quicker...;)
 
audi upgrades
You can get any factory turbo to spool a tad better or to spike in mapping.. the reason the J valve does is because the map is tuned to the response of the valve thats fitted from the factory... the map applies a duty cycle to the N75 (for the most part 90-100% on initial spool) then catches the spike before it happens... the lazier J valve doesn't react as quick as the mapping expects which causes the spike... the map has several protection maps (both ME7 and ME7.5 so the APY isn't special) that come into play if the deviation from requested boost is too much for too long and then puts the ECU into limp mode... most mapped cars can have this played with and is generally lifted so that the tuners can give that extra kick that customers want from a remapped car... this is generally why they work more reliably on 'mapped' cars over std cars...

The OP has a std car... he is experiencing boost spikes that are sending the ECU into limp mode... correct diagnosis of this would be to put the car back to std configuration and take it from there...

Fitting a J valve won't make my turbo spool any quicker than it does... it would still spike too... mine is mapped to be more progressive to prevent surge and stop everything getting too hot too quick... I can make mine spike in mapping if I really want to but I don't..

A J valve is just a pikey way of getting a tad more more kick out of an otherwise std map or a generic stage 1/2 map... the more switched on tuners (Badger5 and R-Tech for example) custom map stage 1/2 to the hardware of the car... this is more of a requirement these days as the age of the cars mean generic maps no longer work as well on turbo's/engines that have a few miles on them...

<tuffty/>
 
The J valve is from the older 5 pot S2s iirc, the older turbos were lazier than the small K04's.

Narrow band does have problems from my experience on A4's. It makes for a spikey initial sppol that drops off quickly . The car becomes harder to drive smoothly IME

The OP needs to replace what sounds like a faulty valve ( regardless of designation) and revert to standard to start diagnostics. Bare in mind we are on the web, none of us have seen or logged this car, so we are suggesting ways of fixing it.

I wouldn't suggest replacing the J valve withj another in this case, revert to standard is the way forward. Dave, I'd do the lottery tonight if I were you, you are very lucky to have had this valve work on all these vehicles that most other people have problems with.
 
Dave, whether it works on your car or not, the simple fact is, the J valve is wrong for the car, and they DO cause many cars to go into limp mode.

Whether yours works OK in this instance is largely irrelevant, all cars are unique as we know, and more often than not a J valve will cause issues.
 
Prawn said:
Dave, whether it works on your car or not, the simple fact is, the J valve is wrong for the car, and they DO cause many cars to go into limp mode.

Whether yours works OK in this instance is largely irrelevant, all cars are unique as we know, and more often than not a J valve will cause issues.
Click to expand...


If you say all cars are unique, how can you then say that it won't work on the OP's car?!?! It works on Dave's and he is letting the fella know that it might be an option..
 
s3dave said:
:think: Doesn't make it wrong either, Narrow band cars seem happy with the valve, ive had mine since i got my car, and before that on mk4 golfs, from what i understand they are of a higher frequency that operates faster than a standard valve, and as the OP as an APY i dont think it will be the Valve causing his issues...as while they are quicker at getting to requested they should not over boost from requested..wasnt it fitted to the TT 225 as standard with no issues?
It would be interesting to see how it reacts on a BT it might get you off the line quicker...;)
Click to expand...

*cough*
Frequency is irrelvant and not the difference. Its not a wideband narrowband ecu thing.

internal orifice size is the difference between the J and normal 1.8t valves

The op issue is unmapped, so boot deviation maps are normal +/- 250mb for x seconds, and beyond that its actuator pressure limp mode special. N75J + mbc etc never going to work on an unmapped car

The appeal of the J valve for some is the extra kick or initial boost, where the requested boost overshoots because the mechanical side of the PID control has been changed. Most folks (mappers inc) dont know how to or dont adjust the map which can prevent these overshoots.. Its "pikey" in that its pretty crude at introducing a spike of boost which is not "map requested"

Several tuners advise these are part of their "tuning advise" but I personally dont agree or subscribe.. (they get to sell you a valve you dont need)

If you want spikey boost delivery, then do it in software during the remap, not by bolting on a part which actively does'nt work with the boost control within the map itself. Those tuners that fit these J valves more often than not Dont write their own maps and could'nt do anything else.

Spikey boost delivery is'nt going to get you anything more than more initial boost/torque, at the expense more often of top end power as that same torque falls away sooner in the rpm range because cyl temps have got too hot too soon.
 
Reesy said:
If you say all cars are unique, how can you then say that it won't work on the OP's car?!?! It works on Dave's and he is letting the fella know that it might be an option..
Click to expand...

Std map in ops car? yea.

remapped car, like daves probably, will have boost deviation limits max'd so they wont cut in.

Std map, boost deviations >+/-250mb will drop into limp mode

Simples

hope that explains
:)
 
badger5 said:
*cough*
Frequency is irrelvant and not the difference. Its not a wideband narrowband ecu thing.

internal orifice size is the difference between the J and normal 1.8t valves

The op issue is unmapped, so boot deviation maps are normal +/- 250mb for x seconds, and beyond that its actuator pressure limp mode special. N75J + mbc etc never going to work on an unmapped car

The appeal of the J valve for some is the extra kick or initial boost, where the requested boost overshoots because the mechanical side of the PID control has been changed. Most folks (mappers inc) dont know how to or dont adjust the map which can prevent these overshoots.. Its "pikey" in that its pretty crude at introducing a spike of boost which is not "map requested"

Several tuners advise these are part of their "tuning advise" but I personally dont agree or subscribe.. (they get to sell you a valve you dont need)

If you want spikey boost delivery, then do it in software during the remap, not by bolting on a part which actively does'nt work with the boost control within the map itself. Those tuners that fit these J valves more often than not Dont write their own maps and could'nt do anything else.

Spikey boost delivery is'nt going to get you anything more than more initial boost/torque, at the expense more often of top end power as that same torque falls away sooner in the rpm range because cyl temps have got too hot too soon.
Click to expand...
I love the kick Bill....;)
 
riteeeee guys... i managed to get hold of a 'F' black valve.... i fitted it without the MBC all to tufftys description. an my car was boosting at about 7psi..... weirdly.... so then i fitted the MBC in between the charge vaccum pipe to the n75 an its running 12psi an if i turn the MBC it doesnt make much difference, still holds 12psi.... im confused. but i managed to pick up a bargin of a remap of a lad on FB for a custom map from a company called redbitz in cannock for monday. so im hoping it will run sweetly after that!? any advice??
 
A postal remap?..if so be careful, you really should get it running sweet standard before any remap, as all that is going to happen is the map will amplify the problem,,,
 
Ino it could mess it up possibly but also they should diagnose the car first surely prior to mapping? An also with a map i might be able to take the mbc out an it will run sweet with the "f" n75!? I really dont have a clue what else to do or try now iv done an tried everythink you guys have said. Thanks alot for all your help aswel! As it stands the cars running ok holding around 12psi with the mbc in with the n75 :s
 
*** fella...

are you deliberately trying to get MORE BOOST than its designed to do WITHOUT a remap???
ditch the mbc....
remap will sort it, IF its a decent remap and IFits done by someone COMPETANT

good luck

you're likely to need it messing about like you are
 
Well yeh like i said hopefully i want to get rid of the mbc, i hope this garage can sort it. I only know what i read so im learning as i go on, an if standard boost is 12 and with the mbc in like before it runs that then that is what i was gunna leave it as!?
 
The point is you are using a MBC on a standard car to control boost, and there should be no need to, so you have a problem before a map that will need sorting, are you sure there is no map on it?
 
limbo118118 said:
Well yeh like i said hopefully i want to get rid of the mbc, i hope this garage can sort it. I only know what i read so im learning as i go on, an if standard boost is 12 and with the mbc in like before it runs that then that is what i was gunna leave it as!?
Click to expand...

12-14psi is the std level yes.. so remove mbc...
get it mapped "properly"

Sorted
 
you can't rely on this MBC to get you to standard boost.

THe point we're trying to get across, that so many people don't seem to understand, is that rather than bodging your way around a problem, you need to get to the root cause of it.

This MBC bodge may well have no got you back to factory boost, but there must be a reason it isn't meeting this on N75 control only.

Without finding that cause first, this remap will be of 100% zero use to you at all, and will only stand to make matters worse.
 
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