8N TT 225, has bad turbo flutter, what’s your thoughts on it?

[YotoWerks]

This is how I bought it, apparently it’s been running fine but I do have a lean code and CEL.

Listen to it.
https://youtu.be/ieemHLUMZ-4


Sent from my iPhone using Tapatalk

[Tiberius73]

That sounds like classic compressor surge.
Judging by the fact that it seems to happen as you lift off the throttle rather than just 'randomly' it isn't a fault as such but rather because someone has removed or disabled the blowoff valve. Or the currently fitted one is too small. Sometimes also called a diverter valve or anti-surge valve. A vacuum line connects the intake manifold to a spring-loaded piston device inside the blowoff valve, which keeps the valve closed. When the pressure differential between the intake manifold and intercooler piping reaches a certain level, the blowoff valve spring is depressed. This allows the excess air to be released from the system, preventing it from flowing backward to the compressor.

The problem is that unless this is a specifically modified turbo, the flutter is causing heavy vibrations/shock to the turbine which is wearing the bearing rather hard if you lift off the throttle at high boost and rpms (e.g. when shifting up on WOT at 5k rpm).
As low boost/rpms, it really isn't so dramatic.

I've killed a K04-023 turbo in less than 400 miles when hill/canyon racing like this.
It also doesn't give any performance advantage. It is just a 'boy ricer' noise with no advantage of any kind at all.

[rfelker]

Swap the DV its on backwards. you will get a flutter sound when its on this way. From the pics its not in blowoff mode its capped. So that should be good to go.

[asiwa]

This is how I bought it, apparently it’s been running fine but I do have a lean code and CEL.

Listen to it.
https://youtu.be/ieemHLUMZ-4


Sent from my iPhone using Tapatalk

For me this issue was related to a vacuum leak in one of the lines that runs from the N249 valve assembly (second picture) underneath the intake manifold, specifically the leftmost of the two that are secured by the tan retainer. It began as only mild turbo flutter but it has nothing to do with the orientation of the DV, and that is confirmed by the CEL. If you remove the black dipstick mount plate in front of the intake and reach underneath, my bet is that you'll find one of those vacuum lines is rotting and torn.

What I will mention as well is that your DV is most definitely not stock - it appears to be aftermarket and may even be a full-on blowoff valve. The 1.8T is designed to run optimally with a diverter valve, and unless the car has a big or modified turbo an aftermarket DV is generally unnecessary.

You can replace that one with the OEM version, PN# 06A145710N or the "P" revision which I believe may be the most recent. They work great and even though I replaced mine as a precaution, the one that was installed from before I bought the car six years ago was still in good condition.

Sent from my Pixel 2 XL using Tapatalk

[YotoWerks]

For me this issue was related to a vacuum leak in one of the lines that runs from the N249 valve assembly (second picture) underneath the intake manifold, specifically the leftmost of the two that are secured by the tan retainer. It began as only mild turbo flutter but it has nothing to do with the orientation of the DV, and that is confirmed by the CEL. If you remove the black dipstick mount plate in front of the intake and reach underneath, my bet is that you'll find one of those vacuum lines is rotting and torn.

What I will mention as well is that your DV is most definitely not stock - it appears to be aftermarket and may even be a full-on blowoff valve. The 1.8T is designed to run optimally with a diverter valve, and unless the car has a big or modified turbo an aftermarket DV is generally unnecessary.

You can replace that one with the OEM version, PN# 06A145710N or the "P" revision which I believe may be the most recent. They work great and even though I replaced mine as a precaution, the one that was installed from before I bought the car six years ago was still in good condition.

Sent from my Pixel 2 XL using Tapatalk

Yes I fixed it, I found the vacuum leak that you are talking about and it fixed it! I got the 710 valve new and I was lacking boost so I went to the aftermarket one again and everything is good now!
Thanks for the input!


Sent from my iPhone using Tapatalk

[quattrosnrabbit]

Please tell me you did something about that filter too. Poor thing looks like it hasn't been serviced (cleaned and oiled) in so long that it's rusting...

[hightime80]

Yeah classic hot air intake lol

[WarmFuzzies]

I have that same exact lift off noise on my car — noticed the other day out on a test drive

Stock 1.8

I’ll search for a vacuum leak too


Sent from my iPhone using Audizine

[asiwa]

I have that same exact lift off noise on my car — noticed the other day out on a test drive

Stock 1.8

I’ll search for a vacuum leak too


Sent from my iPhone using Audizine

If your motor is bone stock there is also a chance that the DV itself is bad, although I've seen very few instances of the revised 710N version going bad. If the valve is original it could be the earlier, weaker part.

Most likely a vacuum leak from the hose that runs under the intake.

Sent from my Pixel 2 XL using Tapatalk

[WarmFuzzies]

If your motor is bone stock there is also a chance that the DV itself is bad, although I've seen very few instances of the revised 710N version going bad. If the valve is original it could be the earlier, weaker part.

Most likely a vacuum leak from the hose that runs under the intake.

Sent from my Pixel 2 XL using Tapatalk

Thanks — I suspect the DV is bad so I’ve ordered a new one from ECS and will swap it in next week so stay tuned.


Sent from my iPhone using Audizine

[WarmFuzzies]

Thanks — I suspect the DV is bad so I’ve ordered a new one from ECS and will swap it in next week so stay tuned.


Sent from my iPhone using Audizine

Update: new DV fixed my flutter. Car purrs like a kitten after lift-off


Sent from my iPhone using Audizine