Whistling sound under high boost?

[Nautilus]

Hello everyone

For some time I was hearing a weird noise under hard acceleration: a whistle (or a combination of whirring and whistling) while pushing the throttle hard. It did not happen always at the same rpm and boost, sometimes at 0.5bar, sometimes at 1bar or 1.4bar, sometimes at 4000rpm and sometimes at 5000-6000rpm, and not even all the time throttle was pushed, only 1 time out of 5!!!!

The engine rumble did not change, only the whistling appeared over it

As I did no longer heard the "pssssssssst" sound of the DV when whistling (I have a Forge 006) I suspected the DV piston is stuck, and it moves "like the ball in a whistle". Should check the DV tomorrow morning and oil it a bit

What else should I check, boost leaks?

~Nautilus

 

[theyellowone]

A friend of mine owns a Skoda RS (1.8t 20v), he had a whistle noise, think it turned out to be a leaky intercooler?!

 

[Nautilus]

Oiled this morning the piston of the Forge DV, drove a bit , pushed the throttle hard a few times, it did no longer whistle. If it doesn't anymore in the next few days, I've solved it

~Nautilus

 

[Nautilus]

If a boost leak did happen, why does the gauge show it holds pressure (even in the 1.4-1.5bar range)?

(Gauge is connected to the top of the DV)

~Nautilus

 

[mr_D]

then that will be the reason it doesnt show a difference. plus im sure if the dv was stuck then you would get wastgate chatter which is a myth for the turbo stalling due to air not being released, if you have an induction kit on it of any kind then it could just be turbo whistle which is fine and sometimes concidered a good thing

 

[Nautilus]

Since yesterday the metallic whistling has appeared only once out of a few times the throttle was pushed hard, a sound like a huge "police whistle". However, I suspect some detonation (pinging) since I have run for a week with my spare coil pack on cylinder #1 (the original coil pack had blown) and it triggers the Check Engine Light in the dash. There were above 38 degrees C (100 degrees F) around and with a coil which is not 100% perfect and high boost, detonation might have happened

The new set of coils is to come in 1-2 days

~Nautilus

 

[freegeek]

If a boost leak did happen, why does the gauge show it holds pressure (even in the 1.4-1.5bar range)?

(Gauge is connected to the top of the DV)

~Nautilus

I has a tiny boost leak which had a very loud woshing sound that did not apear to impact my max boost.

After a lot of searching starperformance found that it was this pipe going to the braking system.

 

[mr_D]

I has a tiny boost leak which had a very loud woshing sound that did not apear to impact my max boost.

After a lot of searching starperformance found that it was this pipe going to the braking system.

brake servo hoses. was a recall on the mk3 ibiza cupra

 

[strugers1]

i have that now on my tdi!!

 

[Nautilus]

Whistling has not disappeared, changed to a metallic whirr/buzz. It appears randomly, sometimes at 0 bar, sometimes at 1 bar or over, usually when throttle is pushed only a bit at high rpm (when accelerating from 4000rpm boost raises quickly at the slightest touch of the throttle, it does not need flooring the throttle like it does at 2000rpm and high gear). Boost does not fluctuate, acceleration is smooth, but it's annoying because it makes me to suspect damage to the turbocharger

~Nautilus

 

[Nautilus]

The strange sound still present, like a metallic whirr or something grinding, appears mostly at 1 bar of boost and is louder at ~1.5bar, enough to cover engine rumble and intermingled with DV whooshing

Can it be turbocharger damage? If the turbo is damaged shouldn't the engine behavior change, fluctuating power, juddering, power loss, smoke etc?

On the other side: wher other members got damaged turbochargers (sorry for them) did their turbos do such strange noises before blowing up?

~Nautilus

 

[Nautilus]

Searched the forum, there was a member with a similar noise at over 1 bar of boost:

http://www.seatcupra.net/forums/showthread.php?t=116642

The reason for the noise in that case:

"basically the N75 valve was connected with cheapo blue fancy hose (Not Samco !) and what was happening was, the weight of the N75 vlave was pulling the hose such that it was kinking the charge line. When the pipe was cold the restriction (kink) in the pipe was basically not opening the waste gate quick enough and I was getting this boost spike which was causing the pinking.
When the car and pipe heated up - the pipe went soft and basically would move and react to charge pressure quicker, push the actuator quicker and hence no pinking.
When the car was left overnight the charge pipe to the N75 went cold and stiff and would cause a restriction to the actuator and hence wouldn't open the wastegate quick enough - hence rapid boost = pinking."

Inspected my N75 hoses for similar issues, but found no restriction, and therefore I suspect N75 failure.

Which version should I choose as a replacement?

The valve on my car is a "F" type.

As my remap has a huge boost spike around 3500-4000rpm, I'm interested in the smoothest-acting version. As I've found searching around, N75H is thought to be smoother and N75J more "spiky".

~Nautilus

 

[Nautilus]

Changed the Turbo Intake Pipe for a Forge silicon duct in the mean time.

Noise still appears, when the boost is high (close to 1.5bar) and the throttle slightly open, such as when throttle is pushed at slow rpm in high gear. At full throttle, revs over 4000 or both, it does not happen.

Two possible reasons are: 1) detonation/pinging due to running lean (high boost and too little petrol flow) or 2) surging

~Nautilus

 

[drvince]

What do you mean ????

A turbo car is supposed to have the whistle.
I love that sound !

 

[mrwookie]

Changed the Turbo Intake Pipe for a Forge silicon duct in the mean time.

Noise still appears, when the boost is high (close to 1.5bar) and the throttle slightly open, such as when throttle is pushed at slow rpm in high gear. At full throttle, revs over 4000 or both, it does not happen.

Two possible reasons are: 1) detonation/pinging due to running lean (high boost and too little petrol flow) or 2) surging

~Nautilus

I'm having the same issues as this at the mo with my LCR. Just out of intrest what remap do you have?

 

[mrwookie]

Did you ever get this sorted Nautilus?? I tried changing the N75 on mine and it made it a bit better but still there

 

[Nautilus]

Sometimes still happens, same conditions: high boost, slightly open throttle. Only cure seems to be pushing the throttle down

I'm almost sure by now it means surging

Remap is Dimsport (Race2000)

~Nautilus

 

[johntheboy]

I'm having this problem at the moment on my '05 Tdi. It tends to be when i set off when the car has been sat still for an hour or more. Ill rev the engine or set off and when the turbo starts to deliver power i get a squeek sound which I can only describe as what sounds like a fan belt slipping. Is this what everyone else seems to be getting? Would the problem be detected on vagcom, I rang one garage and thats what they said they would do first. This is really driving me mad now.

 

[Nautilus]

After the weather thawed a bit, tried some running around (in the dead of winter it would have been a bad idea on a remapped 1.8T )

Metallic whistle appears to be gone for good, at least as the outside temperatures are around 10 degrees C. On the other side, turbocharger makes a very loud whooshing sound under strong acceleration, even louder when throttle is not 100% opened. I mean loud enough to cover the engine rumble altogether, and it sounds like a giant caged fan or an aircraft taking off (before anyone asks, I know the turbo itself is a fan). DV sound is practically inaudible when releasing the throttle, or it's covered itself by the whoosh.

I understand turbo spooling up should make some noise. On the other side, it can hardly be a boost leak, the gauge shows full boost available while the sound is clearly not the thin ear-piercing hiss produced when air is pushed through small openings.

I have also a 3"downpipe fitted on stock cat-back exhaust, Forge TIP, large duct to airbox, and engine rumble in itself has diminished after these had been fitted.

Later Edit: checked the TIP and accessories fitted (DV, N75, PCV), all three screw clamps were loose, N75 could be pulled out by hand. Smeared a bit of sealant on N75 stem, tightened the screw clamps as tight as possible, waited a few minutes for the sealant to dry, tried a bit the turbo in traffic - whooshing-whistling sound has diminished a bit, it does not cover engine rumble anymore, but it's still loud

Which is the normal sound of a remapped 1.8T turbo spooling up?...

Thank you

~Nautilus

 

[Nautilus]

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