Boost/Vacuum Issues

[KieranM]

I was recently in at Ecotune getting my ED30 mapped from stage 1 to 2+. When the car was on the dyno it only made 284bhp with all 2+ mods (made 307 before on completely stock hardware). They loaded on then 2+ map anyway and now when the car hits around 3k it is just completely flat and very very little boost. The car is still boosting before 3k as you can hear it spool.

The guys at ecotune reckon that it is down to a vacuum leak somewhere in the system. The PCV was checked by opening the oil cap when the car was idiling and the car started hunting so they said the PCV is fine.

I have checked all the boost pipes and they are all on and secure so I have ruled them out. The DV has also been checked and is fine.

What else should I check or what can it possibly be? Is it worth while getting a smoke test done? And is there any thing I can log in VCDS to help pin point the issue.

[bradh]

Does it build boost back up after 3k i had this and it turned out to be seal had gone on boost pipe

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[pudding]

Yep, usually the Bayonet O-rings, especially at 3K on stage 2 where the KO4 really starts to kick hard.

[Shamm]

@Pudding i have the same problem where is that ring located ?

[Paradox1]

driver side of the engine bay. pipe that comes of the turbo. should be able to see it from opening the bonnet but obviously need to be under the car to sort it

[pudding]

There's 4 of them in total on the GTI/Edition 30:

1 on the turbo outlet
2 on the intercooler
1 on the turbo discharge pipe > intercooler

I've deleted all of them, by:

Fitting an S3/6R intercooler (can mod the GTi/Ed30 hoses for that, but 6R hoses are a better fit)
Fitting a Forge Motorsport 6R muffler delete kit
Chopping the Bayonet off the discharge pipe and welding a section of 2.25" on the end.

The boost is very consistent now.  Put my foot down, it just goes.   I used to have the same problem.  Get to 3K and it just backed off, then built again, backed off, went flat, then pulled to redline OK.   Never got any fault codes because the N75 just adjusted to get the target boost.  If it gets severe enough, you'll get a "underboost" fault code, but normally only see that from a split DV.

[KieranM]

The boost won't build back up after 3k, it's just flat all the way and takes ages to get up the rev range after 3k.

When the car is sitting idiling it occasionally gives off what is like a little misfire but I've checked in VCDS and it does to register any misfire counts. I'm not sure if it's related to my boost issues though.

[pudding]

Sounds mechanical then.   Broken ring land(s) maybe?  Time for a compression test I think.  Sounds like the cylinder(s) is/are hitting the max pressure they can sustain at 3K, and then the boost is just blowing into the crank past the piston(s).  Should be a lot of PCV oil in the boost path when that happens, and oil consumption increased.

Kind of seems that way doesn't it if there's no fault codes, it misfires at idle, and it was making less power than it should when you took it in?  I really hope it isn't that, but it does seem like a mechanical issue from the descriptions.

[Pesky jones]

Pudding, your boost would build again after 3k presumably because the leak would close itself...?  Could it be that Kierans isnt closing again

[KieranM]

I thought that the ring landing had cracked last month as it was misfiring top end but we did a compression test and it was all good. It turned out to be a combination of a dodgy injector and failing HPFP, both of which were replaced and has cured the top end misfire. The misfire on idle sounds like it's only the one misfire every couple of minutes.

[pudding]

I thought that the ring landing had cracked last month as it was misfiring top end but we did a compression test and it was all good. It turned out to be a combination of a dodgy injector and failing HPFP, both of which were replaced and has cured the top end misfire. The misfire on idle sounds like it's only the one misfire every couple of minutes.

Have you done any logging to see what happens at or just after 3K?   Sounds like the engine is OK mechanically then, which is good.

[Shamm]

When im driving after 4k revs it doesnt wanna go anymore sometimes it does but not much

[Paradox1]

Any error codes? needs logging

[Shamm]

I havnt got it scaned yet i finding someone local yet

[Paradox1]

Worth investing in VCDS lite