My understanding was that it held some boost between 1st and 2nd gear changes and cut the boost if in an accident but BAMs are fly-by-wire which cuts the throttle in an accident.

Does your car also have an SAI (N112 ?) eg APX , that may have to be deleted hence why all the T pieces. And blocked pipes?

On my BAM I just removed the jungle, container and bracket pipe from on top of cam cover and disconnected from DV and inlet manifold, then ran a new pipe from inlet to DV, and then reconnected the N249 electronically and tie wrapped it out the way.

Junking the PCV and the n249 really simplifies the vacuum and breather.

 

The N249 valve will open the DV when cruising when the ECU asks for reduced boost for better fuel efficiancy, it will also open the DV valve quicker on gear changes or throttle lifts.
I looked at the delete but thought it was beneficial to keep it.

 

Yeah I did read about it being used to act like an N/A engine when cruising.

 

Does anyone saying I read about the operation or behaviour have any factual information from a VAG document to support those opinions.?

the cruising reference? well when cruising you hover on the throttle so anytime you lift and boost flickers into vacuum the DV may be opened.

Its an anti lag device and the VAG documents describing it say its an anti-lag device. Get me some reliable info on this overboost protection because as far as I know the n75 is doing its job, hit an overboost in mapping and it cuts you into limp mode.

Read the Transcript , its a perfect call! - N249 - There is no decelleration of the compressor wheel = Anti-Lag.

 

Does anyone saying I read about the operation or behaviour have any factual information from a VAG document to support those opinions.?

the cruising reference? well when cruising you hover on the throttle so anytime you lift and boost flickers into vacuum the DV may be opened.

Its an anti lag device and the VAG documents describing it say its an anti-lag device. Get me some reliable info on this overboost protection because as far as I know the n75 is doing its job, hit an overboost in mapping and it cuts you into limp mode.

Read the Transcript , its a perfect call! - N249 - There is no decelleration of the compressor wheel = Anti-Lag.

It's just what info we come acros and use as we see fit or choose to understand.
But who said anything about overboost protection? I said it will reduce the boost when asked to for fuel ecconomy.

 

It's not just about what you've said , its the posted a link to someone who's posting opinion on what he's learnt and is talking about overboost and boost control.

And as he's posting opinion again with no actual reference to anything that's credible I'm referring to this and all the typical theoretical posters out there that i see the same type of "Fake News" opinion on what the n249 does outside of what an actual reference document says it does.

Don't shoot the messenger I've posted an actual VAG document page on its function from the TT study.

Just would like to see something technical that's reliable and refers to the alternative functions that people represent rather than propagating the same info derived from the first surfer dude that spun a story of his removal and how it felt great when he did it.

This post talks about reinstating it which is recommended.
I'm already of the opinion it was a mistake by the previous owner removing it because of said surfer dude!

I've been in this platform for 18 years and gone through testing the removal of the n249 and 100% you remove it there is a moment of audible compressor surge on lift off which goes away when it's in-place.

More boost and a bigger DV will highlight that and I'm also highlighting that it does what it says on the tin with many years of experience.

I can say that I believe he is fundamentally wrong saying dv response is faster removing it both from experience, testing and from a technical manual stating it does the exact opposite of what his opinion is claiming.

Just be careful what you read and what you repost or you may propagate something false or at very least check into some credible references.

If it actually has some kind of boost protection which I've never seen, it's a protection feature, why would you remove something that's 99% good as an anti lag device and remove it because 1% of the time it's going offer some engine protection when you may need it?

The ability to open the DV faster in cruise situations you mention may well be useful but it's less of a benefit than it is when at WOT and gear change when you want to keep the compressor spinning.

 

It's not just about what you've said , its the posted a link to someone who's posting opinion on what he's learnt and is talking about overboost and boost control.

And as he's posting opinion again with no actual reference to anything that's credible I'm referring to this and all the typical theoretical posters out there that i see the same type of "Fake News" opinion on what the n249 does outside of what an actual reference document says it does.

Don't shoot the messenger I've posted an actual VAG document page on its function from the TT study.

Just would like to see something technical that's reliable and refers to the alternative functions that people represent rather than propagating the same info derived from the first surfer dude that spun a story of his removal and how it felt great when he did it.

This post talks about reinstating it which is recommended.
I'm already of the opinion it was a mistake by the previous owner removing it because of said surfer dude!

I've been in this platform for 18 years and gone through testing the removal of the n249 and 100% you remove it there is a moment of audible compressor surge on lift off which goes away when it's in-place.

More boost and a bigger DV will highlight that and I'm also highlighting that it does what it says on the tin with many years of experience.

I can say that I believe he is fundamentally wrong saying dv response is faster removing it both from experience, testing and from a technical manual stating it does the exact opposite of what his opinion is claiming.

Just be careful what you read and what you repost or you may propagate something false or at very least check into some credible references.

If it actually has some kind of boost protection which I've never seen, it's a protection feature, why would you remove something that's 99% good as an anti lag device and remove it because 1% of the time it's going offer some engine protection when you may need it?

The ability to open the DV faster in cruise situations you mention may well be useful but it's less of a benefit than it is when at WOT and gear change when you want to keep the compressor spinning.

As i understand it, it does what you say. I can't understand why people remove it after reading what it's for, but upto them as they say.

I read about people recomending it's removal, read up on it and decided removal was the wrong thing to do.

 

People mainly remove it when there's a problem as it's cheaper and easier to do.

People like to delete them on the S4's with other bits too, I've kept my fully functional for these very reasons.

 

People mainly remove it when there's a problem as it's cheaper and easier to do.

People like to delete them on the S4's with other bits too, I've kept my fully functional for these very reasons.

For sure I have only worked on a lot of TTs and not the whole VAG turbo range but in all my years only 2 TT's have had problems and both were from being manhandled badly.

Vacuum resevoir pipe is glued, pull it off and youve broken the seal.
other pipes bent and cracked and replaced by gasket sealent and still split

Thats it most N249 faults are actually faults in parts like the DV or somewhere else in vacuum pipes, maybe in distant memory 1 solonoid failed ( TT no. 3) but in my experience it is a very reliable setup and unfortunately needs man handling to do plugs and coils.

Mondo has a nice setup here he's just relocated it so its hidden and still functional which is what I would recommend.

Essentially it is only making DV functions from 95% efficient to 100% efficient so if the 5% is not a bother then remove it but it is better to have it than not.

 

Thanks for clearing up the position Wak, while not ideal there may be benefit from having the debate in one place.

So looks like I will need to look to reinstate the system. You mentioned that one of the hoses was glued so sounds like I need to find a second hand one with the pipe intact. Will need to work out which hoses go where as the fitment under the electrical connector has nothing on it at present and the two on the other side short loop to each other. Even looking at your schematic it is not totally obvious, not sure what grey box with the chevron is?

When ever it was done in the past, would it have needed a remap to finish the removal and hence it will need remapping to add it back?

 

I'm not sure you can map the 249 out, that's the reason most "removals leave the solenoid in place because the ECU is monitoring its operation and will generate a fault code if it's removed or not replaced with a load resistor. I like Mondo still have the 249 connected but I defy you to find it :roll:

 

A hide a seek challenge!

I would guess that the wiring loom may be the limiting factor for the solenoid and the hose from the top of the DV is running down near the TIP and the air box is gone so probably space there for the resevoir, not sure about the solenoid though unless the wiring loom allows it to be moved the that area?

If you have the plumbing arrangement that would be great, and thanks for the logic on the delete process, hopefully I can just plumb it back up and be good to go.

 

if you are putting it back you will need the bracket as well

hiding N249 and vaccum gubbings ?

 

You can map out the open circuit DTC and then you can have it in or out and it will work as normal except if it actually goes open circuit and you wouldnt know.

the DTC doesnt cause an light on the dash so its not essential so long as you know a fault scan will see a fault then its not neccesary to map it out.

This picture looks like it shows enough to set it back up.

the pipe on the vacuum chamber just needs a light smear of araldite with a cotton bud on the outer surface before sliding a tube on, it should hold fine.
Image

 

If you look closely enough you might see that the relay box on my bulkhead is gone......., quite a lot of space behind the scuttle panel...... :roll: