I had yet another guy take a look at it and he said the sound is not coming from the diverter valve, but from another valve which is right near the turbo. This one looks metal and is "behind" the engine towards the passenger compartment and somewhat down so it's really hard to see. I'll try to get a picture of it. Any idea what this valve does?

Ok, took some pictures, but it's really hard to get some light there :(

First picture is the stock diverter valve. 2nd and 3rd are the valve supposedly making the noise.

I "think" thats your wastegate which can "chatter" under certain conditions.

You know like a rally car does.

Iirc it's not good too have this happen on a ko3 turbo.

I may be wrong though.

Yarp, that's the wastegate actuator.

That jubilee clip is not standard, so it's been fiddled with at some point.

Which could be harmless, like a new hose was fitted. But could be not so harmless, and someone has been farting about with the actuator rod to increase the pressure at which the wastegate opens.

Your going to need to get under the car and inspect the wastegate actuator properly. If it's been tampered with, you should be able to see some marks on the actuator rod.

Or there is the possibility that the actuator is just shot, as the diaphrams can go. You'll need to get it pressure tested to check this though. Find someone to run a hysteresis check on it.

I still believe you need to get the car to someone who knows a bit about modified Skodas to give you some idea as to what youve bought. It might be a well tuned car with gremlins or a home bodged set up, where are you in the country & perhaps someone on here can recomend someone

Yarp, that's the wastegate actuator.

Maybe that's what the tuner guy meant by a valve that's 'inside the turbo', even though in this case it's external instead?

Maybe that's what the tuner guy meant by a valve that's 'inside the turbo', even though in this case it's external instead?

Well the wastegate valve itself is 'in' the turbo, as it is a component within the turbine housing.

The wastegate actuator, and actuator rod, are there to open and close the wastegate valve.

If the wastegate valve was broken, you would know about it! As you would have no boost, and a metal disc would go rattling down the exhaust!

Like someone else said, this car needs a good looking at by someone in the know.

I'm in Romania and honestly, it looks like there's no one around who would know :(

Tonight I'm taking off the diverter valve and cleaning/checking it. From what I read on another thread here the noise could be because the diverter valve's not opening, causing the pressurized air blown by the turbo towards the closed throttle to be "chopped" by the turbo fans. This noise would then most likely be audible around the turbo and the air filter casing.

I found a nice guide on forge's site http://www.forgemotorsport.co.uk/valve_service.pdf on how to open and clean the valve then test it, I just hope that the stock one can be opened as well.

I also saw the "tuner" guy who told me he can't help me...

Tomorrow I'm also sending the receipts to the original tuner of the car (Dupre Motorsport) hoping they can tell me what's been fitted on the car (make of turbo, other stuff...).

Here's a picture of the wastegate valve if anyone was interested. This is obvioulsy not a K03, and note the passive wastegate control. The principles are the same though.

A pint to the man who can guess what turbo this is!!

Reading about wastegate chatter on wikipedia:

"There is confusion in the automotive world about so called "wastegate chatter" or "turbo flutter". A noise created on lifting off the throttle in a turbocharged car, commonly described as a chipmunk or a rattlesnake, is often stated incorrectly as being a result of the turbo's wastegate closing.

The noise is in fact the air compressed by the turbo passing back through the compressor wheel of the turbo after the airflow is abruptly halted by the throttle plate closing, called compressor surge. However, in some cases, i.e. where the throttle plate doesn't open fast enough or is set up to only react to high boost, some chatter will remain. Surge can occur on diesels when the turbo is attempting to pressurize the air at a higher pressure ratio than the compressor wheel can flow at a given speed. Diesel engines have no use for a blow off valve as they do not have a throttle plate.

The chatter noise is very noticeable on World Rally Cars, where anti-lag is used.

A compressor stall like this can cause excess stress and wear on the turbo's shaft or bearings under higher load applications of the turbo (around 15psi and greater depending on the trim and flow rate of the compressor side)

Actual wastegate flutter occurs instead under partial boost conditions such as partial throttle near the boost threshold. It sounds like FftFftFft not ShuShuShu and is caused by the rapid opening and closing of the wastegate at boost levels near the spring pressure. It is commonly heard more clearly and may be more prominent on cars with modified intake silencers, up-pipes, and or downpipes, and is not harmful." :confused:

I just hope that the stock one can be opened as well.

The Bosch unit isn't serviceable, is it?

@Bodge: That's a in interesting cutaway - I didn't realise that the valve itself was inside the turbo, but had assumed it came off the manifold. In this instance, doesn't that mean there'll come a point when tuning the Octy without replacing the turbo where the standard valve might not be able to handle the increased boost? Is it actually possible to tune one of these to that degree without swapping the turbo, such that it becomes an issue?

Interesting stuff about wastegate shatter; I'd always thought it was caused by using a poppet valve wastegate and a crude fuel dump anti-lag system!

A pint to the man who can guess what turbo this is!!

A big one

A pint to the man who can guess what turbo this is!!

It's not a turbo; it's a computer graphics illustration!

I met this evening with a guy who's a professional pilot and has had his share of tuned turbo cars. He told me the sound is normal and it's made by the wastegate. Another man another opinion I guess...

What he said though is that the car is not pulling as it should be, or at least that it should be pulling more evenly. Can anyone with a stock rs describe please how the car pulls? Nice and even from 2000 rpm on (this is the feeling in the o2 rs) or (like mine) so-so up to 3000, then better and at 4000 all hell breaks loose?

Another video that sounds like mine:

Edited 11 December, 200817 yr by jmf

Mine feels like a normal car up to about 2k, when you start to hear the turbo spooling up. By 2.5k you can really feel it starting to pull (fidgety wheels in in the wet) and at 3k it's properly on the ball. You can ride that out to around 5.5k when you notice a slight dropoff, and from then on you're only thrashing it with diminishing returns. The boost is smooth throughout the entire range without any noticeable peaks or dropouts. I do get the feeling that the engine management tames the boost in first gear because it knows you'll not be able to put it down fully, but second is a different story altogether

You might find that the engine comes on song more at 4000rpm with the engine being variable valved. I can feel it kick in about that point, but it is usually smooth though. Have you got a tuner with a rolling road to see what its doing?? If its not the DV, then it could be possible caused by a bad map

Ken and Fatty can have half a pint each for effort! Haha!

Oggy, as far as I know the VVT does not come in during normal driving. It's used purely during cold start situations, when it sets the valves to 'massive overlap', something to do with heating up the cat quickly. It runs in conjunction with the secondary air system.

So there is no 'VTEC like' power surge at high revs, just the turbo.

Turbo's are for men. Woof

I might be wrong with this, but I don't know too much about these engines, thats why I pay to get things fixed, but I always thought that VVT allows the lift/duration/timing of the exhaust or inlet valves to be changed while the engine is in operation. My Clio 172 sport had VVT & it came in about 4000rpm like a mild turbo. This allowed for economical driving under 4000rpm. I always thought the principal of VVT was the same & to allow for economical driving & lower emissions. What do I know, I'm here to learn:rolleyes:

Edited 12 December, 200817 yr by Oggy

I've always though theres another slight jump at around 4k tbh.

Maybe I'm imagining it.

I might nip over too UKMK1v's to see what I can find out about the VVT on the 1.8T.

It's only timing and not lift on these, isn't it? Information seems to be remarkably thin on the ground. I can't see why you'd go to the effort of designing it in, and then only use it at startup and not take advantage towards the top of the rev range too.

From Wikipedia

Volkswagen & Audi - VVT introduced with later revisions of the 1.8t engine, and the 30v 2.8l V6. Similar to Porsches VarioCam, the intake timing intentionally runs advanced and a retard point is calculated by the ECU. A hydraulic tensioner retards the intake timing.

It's all greek to me though :confused:

I popped a poston ukmk1v's and itseems hey know about as much as us. lol

Ok, it makes sense now. The point is not to act like VTEC and MIVEC and convert to high lift cams at high engine speeds, but to change the cam timing for better emissions, economy and mid-range torque.

I ordered a 007p valve today from Forge. It's due to arrive next Friday (wasn't that a movie also? ). I'll let you know how it works once I got it.

In the meantime I spoke with the guys from dupre motorsport, they told me that the turbo is custom built (?!), not some standard model. Now I'm waiting for an answer from them about any info they can give me, like the boost it makes...