Whistling sound under high boost?

[FishmanUK]

Got my car mapped less than a week ago and I have started to get quite alot of noise whenever the turbo starts to spool. Didnt do it for the first couple of days. It sounds a bit grindy/whistly. Havent got round to checking the dv connections will do that tomorrow morning. Also would like to check the PCV if I knew where it was !

I havent seen any smoke and most if not all of the power is there but there is also plenty of noise even with light throttle although off boost it sounds normal

 

[LeonFRMK1]

mine had a strange whistle under full boost... changed the turbo gasket and problem solved...

 

[courtney gray]

ive got a problem with my boost on my seat ibiza cupra mark 3 ive changed mostly everthing pipes etc but my mate had a mess with my actuator and he could move it quite freely by hand couuld this be my problem can anyone help me

 

[Nautilus]

Whistling disappeared for good last April, after the manifold/turbo gasket had been changed.

~Nautilus

 

[courtney gray]

if my actuator move freely buy hand does that mean its buggered cus my mate told me your not supposed to move ithem that easy can anyone help me

 

[Nautilus]

Actuator works on turbo pressure, so I'd say if it can be moved by hand is shot

~Nautilus

 

[courtney gray]

thanks for your help so the first thing is to change the actuator not the manifold gasket or turbo one

 

[courtney gray]

where is the best place to get a decent uprated actuator from i cant find one or as anyone got one for sale on the forum

 

[richybigman]

Contact Forge to see if they do one.

 

[mr_D]

they are not that hard to move by hand on any of them!

 

[stevo lcr]

Pulled DV and PCV out, double-checked all screw clamps, tightened them with a large screwdriver. All of them were loose Whooshing sound diminished itself to usual turbo whirring

"Common knowledge" among mechanics and enthusiasts says increased turbo noise is a sign of bearings giving up and turbine grinding when it appears in conjunction with other unusual things: oil consumption, smoke, fluctuating boost, lack of boost altogether

~Nautilus

Another thing to look for is aluminium powder in the turbo pipes,created when the turbo blades hit the inside of the housing.Thats when you know its time to get your credit card out!!

 

[courtney gray]

lack of boost

ive changed almost everthing ive had my turbo checked and it dont smoke what so ever so i dont know what it could be im running out of idears please can someone help me on this forum

 

[Nautilus]

Whirring returned after major engine intervention last October. It happens usually under a combo of part-throttle, high-rpm and low boost.

Finally identified it as "wastegate flutter at part throttle" and found out it's a common occurence on mapped and otherwise modified 1.8Ts and 2.0TFSIs.

History

1. It appeared at first after remap and DV change to a Forge 006 item.

2. Diminished with various fittings to improve engine breathing.

3. Found out I had a loose turbo bolt.

4. Boost was smooth, boost gauge needle did not fluctuate, noise did not harm engine operation.

5. Flutter disappeared for good after changing the turbo-to-manifold gasket and turbo bolts.

6. After major engine work (cylinder head off, replaced piston rings, replaced exhaust valves, changed all gaskets including turbo to manifold and manifold to head), flutter / whirr appeared again.

7. Smooth delivery of boost, no crazy spikes, no fluctuations, no harm to the engine, just noise.

Cure Attempts

1. VAG-COM check. No codes.

2. Engine operation: smoother than before valve job.

3. DV checked and greased. Green spring + spacer shim fitted. (DV006 comes with Blue spring, but the 5 year old Blue spring seemed softer by hand compared to a brand new Yellow spring.)

4. Turbo and manifold bolts checked and tightened.

5. Wastegate actuator: checked for tightness.

6. N75 checked for hose integrity and tightness.

7. Throttle body: self-aligned after battery disconnection.

Results

Fluttering / whirring seems to diminish after harder and harder driving, like a sort of breaking-in. It sounds less threatening (or silences itself) as the turbocharger gets hotter after prolonged driving. It usually does not appear below 4000rpm, over 0 bar of boost on the gauge or at minimum (vacuum) figure on the gauge. Best cure is to push slightly harder the throttle to get out of the dangerous part-throttle area.

~Nautilus

 

[Nautilus]

Pulled the Forge DV 006 today to lubricate the piston and O-rings (still with Blue spring) and tried to fit it back in reverse.

It does not impede operation, the valve works by pressure differential on the sides of the piston: that is, if there is pressure in both thin hose (from manifold to the valve top) and charge pipe (connected to the valve side by hose), both forces counteract each other and it stays closed. While lack of pressure or vacuum in the thin hose combines with pressure in the charge pipe to move the piston and dump boost. (It works somehow like the triple valve of an air brake on a truck or train.)

So, if fitted in reverse, the pressure from the charge pipe would push the dimpled bottom of the piston instead of the curved side, but the pressure differential between piston top and piston sides/bottom stays the same.

Tested it on a stretch on open road to see if it still holds boost as it should.

Conclusion:

+ It still holds boost up to 1.5 bar at lower rpm.
+ It still holds boost over 1 bar at 6000 rpm (throttle had not been pushed to the floor, so it may hold even better than 1.1 bar).
+ It does not appear to spike anymore, as weird as it sounds - boost raises and stays there.
+ Sound of wastegate whirring / fluttering disappears. (Why?)
+ Spooling is slightly quicker.
+ Dumping boost is slightly quicker.
+ Acceleration feels a bit quicker and smoother (but why?).
+ Engine feels a bit more lively under throttle (due to quicker spooling). In fact, it raises rpm and torque so quick that movement of the engine under torque can be felt in the chassis, despite the Powerflex dogbone.
+ Sound of dumping is just as before, a slight "pssssssh" instead of the loud noise of the splitter BOVs or open-air BOVs.

Later Edit:

Explanation:

"Piston type:

Boost to bottom of valve
Return to side of valve

Putting it this way allows the pressure from the turbo to help open the valve quicker. If you put it in backwards you end up with boost pushing on the side of the valve forcing it against 1 side of the valve body, this can also cause the valve to start leaking since the valve is not sitting 100% straight."

http://www.audiforums.com/forum/b5-models-69/dv-valve-reverse-158753/page2/#post1254498

~Nautilus

 

[Nautilus]

Had a small and annoying boost limitation to 0.6 bar / 8 psi in the meantime (May-June 2013) and suspected the DV to have stuck itself open. Other causes for boost limitations are limp mode (0.3 bar), bad N75, boost leak in the pipes, bad wastegate actuator.

DV usually has to be lubed each 10 000 kms, or each spring and autumn. It had been neglected over time since last spring, maybe 12 000 km.

It had been stuck wide open, against the spring. O-rings were bone dry and stuck like old rubber does. Did not use the same red grease as in the 2006-2011 timeframe, since it doesn't hold for long time, but tried a bit of Ballistol (gun oil, it never fully dries and turns itself into a sort of thin grease over time).

With stuck DV, engine ran well, no flutters, no noises, no whooshing, only boost limited itself. On a car with no boost gauge, the fault would be impossible to detect in time.

To be noted: lube the DV at least once per season.

 

[Adjay]

When I had a wile u deer boost it was the PSV breather pipes and also i t did not loses turbo boost, so I got new piping from creation motorsport. Check out the breather pipes.

 

[Nautilus]

All breather pipes have been replaced a long time ago with either silicone or mesh-rubber hoses, PCV valve is new.

 

[Adjay]

All breather pipes have been replaced a long time ago with either silicone or mesh-rubber hoses, PCV valve is new.

Did that not fix it, usually if your boost is not dropping and you have a whistle its usually breather pipes. Do you still have the n112 and n245 valve and all the piping.

 

[Nautilus]

Nope, what cured the whirring / whistling sound had been the reversal and correct lubrication of the Forge DV and tightening of the hose clamps.