This has just started to happen since boost pipes have been fitted.
Driving along and plant it reaching full boost then itsounds like another turbo spooling up but much louder like a belt slipping. It only does it now and then and sometimes it loud and others not so loud.
It's hard to explain really. Turbo is a 6 month old unit VF34 with Apexi induction kit.

 

sounds like a boost pipe has popped off, check the jubilee clips.

 

Not a scared passanger?

 

bets on up pipe

 

A pipe had popped off whilst driving but I've checked them all and seem fine. It has just been re mapped and is alot quicker so I'm thinking it may be the induction kit as it's alot louder in general. Will take it off and clean it tomorrow. Hope it's not another turbo on it's way out.

 

start car from cold and put your hand round the 3 bolt/2bolt join depending what headers you run

 

Sorry mate but I don't understand, I'm brand new when it comes to these cars, forgot to mention it has a FMIC

 

under the car,you will have 2(oem headers 1 pipe) exhaust pipes running across the engine going into a collector ,(turbo side) then 1 pipe going upto the turbo ,check the joints round this area for leaks and black soot.

 

Will do and thanks again. Update tomorrow.

 

The VF's can tend to "shriek/whistle" at high boost levels reached after a remap. I have a VF30 running 1.4bar peak which does this sometimes and there are some old posts about VF35s on here doing the same. Check the boost/intercooler piping and check peak boost with a gauge but if all seems OK and the car is running well then I'd be inclined not to worry about it.
Kevin

 

All I'm worried about it buying another new turbo It drives well and holds boost no problem. After remap on the rollers it blew a pipe off and then on the way back it blew another one off. Spoke to the lad who mapped it and he said it's running alot more boost but is not running to it's max.

 

Traced fault to dump valve, going to strip it down and clean it up tomorrow along with air filter and idle air valve.

 

Ok thought it was dump valve but just been out and it started again, it only does it now and then and seems to do it when 1.2 bar is reached(max). Can't understand why it does it only now and then? If you easy off the throttle it quiets down. Sounds like a very loud kettle whistleing.

 

had mine mapped started doing the same..had it back on rollers all pipe worked check.etc.it was boosting and running fine. still made the noise 6 month on. had it back on rollers at the scooby clinic still boosting fine still putting out 331bhp and its exactly same as yours some times it dose it sometimes it dont as mr maguire said ithink its just a trait of the vf s ive stopped worrying about now as ive covered about 10,ooomiles and now i dont even notice it ..its got to be the extra boost going throu the turbo..

 

Ok I know what your getting at with regards to VF's doing this but only sometimes? seems odd that it's not doing it all the time though. It is abit worring as it's a very loud shreak but I can't find any pipes off and it boosts and drives fine.

 

Sounds like a boost leak, particularly if you've just had a load of pipework refitted.
I've got a minor one on mine that I can't for the life of me find (and I know what I'm doing). Its been there for months, I need to admit defeat and take it to a specialist.

Makes the car a little laggy and slightly down on power as the fuelling is just off optimum. If its bad it might lead to some detonation when off boost as it'll be running slightly lean, but I've had no signs.

 

Sureley if it's a boost leak it will happen all the time, I have had pipe work done along with clutch, belt, service and remap so it could be anything really.
Andy

 

Hope I haven't misunderstood, but it probably is happening all the time, just you can't hear it? Mine is only clearly audible above 1 bar (or from 0.7ish if the windows open), can't hear it at all at idle (-0.6) which is why I can't find it.

 

Mine does it on boost but only sometimes and sometimes it's louder than others.

 

Well finally found the fault at the weekend and yes it was a boost pipe which had not been secured properly by myself
Thanks for the advise chaps.
Andy