My S3 won't make the boost requested

[dj_rzn]

I just got out from my chiptuning shop and the car it's only making 250hp with hybrid turbo (K04) and max 1.4bar and 0.9 on the finish (redline). It is should do with the current map 1.5 - 1.6 and it should finish around 1.1bar.

I looked for boost leaks, nothing. I checked the DV and looks fine (vacuum test ok). I replaced the N75 a year ago, it may be faulty again? If I unplug the top vacuum line of N75, the wastegate should stay closed?

 

[Gops]

If you disconnect he n75 it'll run on actuator pressure. Which hybrid is it? Any codes? Have you done a smoke test to really rule out a boost leak? Who mapped it?

 

[badger5]

logged n75 duty cycles on block 118? and 115 also

 

[<tuffty/>]

S3 ecu can't see more than 1.5 bar so unless you are using fixed duty mapping or an external boost controller then boost control over 1.5bar is sketchy at best

As bill says... Log 118 and 115

<tuffty/>

 

[dj_rzn]

I logged 115 and the actual value is somewhere around 2200 and nominal (requested) 2400 - 2500. (in full throttle)
I don't really know what internals the turbo has, but I have a picture.
What is fixed duty mapping?

 

[badger5]

and log of block 118?

 

[dj_rzn]

I will check it tomorrow at my repair shop, the log of 115 was done by my tuner and he showed me the results.
What is the 118 block? or what should i see?

 

[<tuffty/>]

I will check it tomorrow at my repair shop, the log of 115 was done by my tuner and he showed me the results.
What is the 118 block? or what should i see?

http://www.ross-tech.com/vag-com/m_blocks/

<tuffty/>

 

[badger5]

I will check it tomorrow at my repair shop, the log of 115 was done by my tuner and he showed me the results.
What is the 118 block? or what should i see?

3 up from the 115 he logged

shows n75 duty cycle.. see how much effort is being asked of the n75 to achieve the boost.
95% is flat out fyi

 

[dj_rzn]

logged again at block 115 and it shows 1.3bar and requested 1.5 bar, the 118 block shows 95.4% for N75, so i guess it's ok?
Could it be the diverter valve? Just ordered a splitter..

 

[Erikn89nl]

Just ordered a splitter..

Fair warning, if you mean a Forge Split-R, don't fit it. If you do, @<tuffty/> will ban you from the forum

 

[<tuffty/>]

split-r is an instant ban I'm afraid...

<tuffty/>

 

[<tuffty/>]

logged again at block 115 and it shows 1.3bar and requested 1.5 bar, the 118 block shows 95.4% for N75, so i guess it's ok?
Could it be the diverter valve? Just ordered a splitter..

No... what that is showing is the N75 is flat out trying to meet the requested boost and failing... however... N75 duty can be at 95% for initial spool then drop accordingly so based on the info you have given its difficult to tell...

If the N75 duty is 95% at the points the map is requesting 1.5bar boost and only getting 1.3bar then its flat out and you won't get anymore boost

As for the splitter... I'd cancel the order... they are sh*te... the end... you are having enough issues getting boost up without introducing another way of loosing it...

<tuffty/>

 

[badger5]

logged again at block 115 and it shows 1.3bar and requested 1.5 bar, the 118 block shows 95.4% for N75, so i guess it's ok?
Could it be the diverter valve? Just ordered a splitter..

oh dear oh dear oh dear

OE DV please dude.. Split-R will introduce a leak.. Don't use one.

your 95% duty cycle means its flat out so not ok if its not meeting request..
a few probable reasons... Leak somewhere, tired turbo, tired wastegate actuator..

Remember however the max it can request is 2550mb (your 1.5bar)

 

[dj_rzn]

The turbo has just been hybridized 8 months ago but i guess they did not look at the wastegate actuator..
I've read on the internet that also the diverter valve fails and can't hold boost well.. anyway i just bought one for tests (it can act as a DV, splitter or like a blow off) , here is a link:
http://www.ebay.co.uk/itm/400963340999?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Not really a fortune so I guess if it doesn't hold boost better than the original DV i will sell it.
You guys were a total help and really appreciate the good advices, i will keep you updated with this, we have to solve it

 

[<tuffty/>]

Sadly as a copy of an already leaky valve it only likely to leak even more...

Old OE DV's are just that... old... they have had a few revisions and the new OE ones are decent and hold 30psi etc with ease... they should last better than before too

Yes its still possible the diaphragm could split but its still a better solution than a splitter/split-r and Forge valves will need routine servicing to get the best from them anyway...

<tuffty/>

 

[badger5]

The turbo has just been hybridized 8 months ago but i guess they did not look at the wastegate actuator..
I've read on the internet that also the diverter valve fails and can't hold boost well.. anyway i just bought one for tests (it can act as a DV, splitter or like a blow off) , here is a link:
http://www.ebay.co.uk/itm/400963340999?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Not really a fortune so I guess if it doesn't hold boost better than the original DV i will sell it.
You guys were a total help and really appreciate the good advices, i will keep you updated with this, we have to solve it

Std DV works fine.. and will not leak unlike what you have posted