DV knackered?

JB_A3_Turbo

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HI,

I read on another post that a failed Diverter Valve will make a fluttering sound and can be heard when in lower gears.

When I accelarate off in 1st or 2nd and take my foot off the accelarator I get what I would also describe as a kind of fluttering noise from the front of the car (I thought this was normal?)

e.g accelarate in 2nd gear past 2000rpm (turbo whisling) take my foot off and a short fluttering noise can be heard.

Is this a failed Diverter Valve and should I get it looked at? I've not noticed any loss in power (it's done it since I bought it about 2 months ago)- I thought it was normal e.g like the whoosh you get from a dump valve on the seat leons with the same engine?

Should I get this looked at immediately?
 

HTC

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Yes this will be a broken diverter. The diaphragm inside has split allowing boost past the valve and back into the inlet.

This loss of boost is causing the drop in power.
The fluttering noise is the valve internals flapping as the air rushes past it.

You won't damage anything if you leave if for now. But I'd want to get it sorted to get the power back.

You can either get a replacement OE item which will most likely faill again, but I would recommend the new "eliminator" valve from Forge Motorsport.

Must admit that the broken valve does sound cool!

BTW, leons have more of a "dump valve" sound as they run more boost, thus more air rushing through the valve. You get this noise on chipped cars as well.
 

starski4578

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its easy to replace yourself mate and it'll only cost you about £30 from audi stealers. Definately sounds like the dump valves gone.
 

JB_A3_Turbo

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ok thanks, at least it sounds as though I don't need to replace immediately or not drive it! But I will get over to audi and get a replacement.

Would I really see a drop in power because of this?, where would this power loss be most noticible? It's has done it since I bought it 2 months ago I'd didn't presume there was a problem since it seems to perform very nicely as it is?
 

HTC

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Yes, if it is leaking alot you will lose some boost pressure. This is directly related to power output.
 

JB_A3_Turbo

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It is safe to fit the forge motorsport DV model:

FMCL007P
 

HTC

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Yup thats the same valve I have fitted to mine, but I'd recommend the new eliminator diaphragm valve from forge which is out or just about to be released.
 

starski4578

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Just thought i'd mention fitting the forge won't increase performance at all if anything from reading past forums it decreases performance. Best bet is to get a new original audi part. Unless its the extra noise your after.
 

JB_A3_Turbo

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I'm interested in getting the forge valve if it's going to easily outlast the bosch valve that audi will otherwise fit. I've heard the bosch DV don't always last very long and I may end up replacing it again?

Surely Audi could fit a better DV instead of the bog standard plastic bosch one?
 

HTC

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If you are leaking boost, then a new valve, forge or otherwise, will increase performance as you would have fixed that leak.

If your current valve is okay, then no you won't see any increase.

Indeed the piston type has a lower response time than the diaphragm type.
 

JB_A3_Turbo

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I'm going to take it in to Audi tomorrow and see if they can diagnose that the DV has definitely failed. I've done about 2k on the clock with it like this (not knowing there could be a problem) and want to get this sorted if it really is a problem and will break something else if it not fixed.

Is the DV essential to the operation of the car? a friend at work says that if the DV fails I'll be calling the AA from the side of the road since the car won't work without it !?!

It's all a bit confusing- Dump Valves I thought were supposed to give an air evacuation noise that's part of the way it releases excess air. I've also read that Diverter Valves generally don't make a noise, if they do e.g a fluttering noise like mine when lifiting off then it has failed or split. I heard Diverter Valves and Dump valves are the same people just call them by two different names. Sho should the diverter valve be making any noise at all?!?

I don't want to fit something that is uneccessary but then again I don't want to risk anything failing as a result of not fixing a potential problem?

Argghhh can anyone try and clarify all this for a very confused new A3 owner!!

Thanks,

Jon.
 

HTC

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I'll see if I can explain how it works. Here is a diagram of the Audi setup. The diverter valve is circled in red.
01valve0sg.jpg


I won't get into too much detail, but when you plant your foot down a valve in the turbo causes exhaust gas to spin it up. This draws the air from the filter(10), through the turbo and pushes it round through the intercooler(15), throttle body and in the engine.
You can see the direction of the air indicated by the arrows. Green is the air sucked in from the filter and purple is air under pressure (boost).
02boosting0dv.jpg


When you let off the pedal, the throttle valve closes. This causes a problem as the air under pressure cannot now enter the engine. We need somewhere for it to go. The vacuum connection on the top of the diverter valve opens it and allows the air to escape.
This is shown by the reversed direction in purple.
03throttlerelease7rt.jpg


If this air wasn't released it would damage the turbo by stalling the blade rotation too quickley.

The difference between VW/Audi engines is they dump the excess air back into the pipe after the air filter. Other cars just dump it out into the fresh air. VW/Audi do this to keep the noise down as they like a more refined image. Other makes like the noise, as do the max power crew :)

On engines with high boost (remapped etc) you will get some noise even with a diverter valve as its just the sound of the air passing through the valve. Think of blowing over the top of a bottle. The harder you blow the louder the noise.

If the valve fails you won't get any boost but the car will drive, but with hardly any power.
At the moment you are allowing a small amount of boost to leak back into the inlet when you put your foot down.

Hope that makes sense.
 

Jodi

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That's a very clear explanation. Where are the diagrams from? Do you have the key to go with them as I'd be interested in knowing the rest of the parts on the diagram?
 

JB_A3_Turbo

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Hi Thanks for the detailed explanation!

The first picture showing the diverter valve isn't coming out for some reason?

I've just rung Audi service department (huntingdon) and stated that I think I have a faulty diverter valve- they claim to have never heard of one of these? They said it could be a dump valve? I told them it wasn't a dump valve? Has anyone got the part number for the diverter valve that I can throw at them!!

Many thanks!!

Jon.
 

HTC

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Not sure why the first pic isn't working. Anyways, the diverter valve is item number (6) in the diagrams.

Some service people aren't very clever. If you don't call it exactly what they have written down in the parts computer then they get a tad confused.

The official part name is a "cut-off valve".

The part number is 06A145710N. If they say something stupid like "we need your chassis number" or thats not for you particular car" tell them to order it anyway. Its the latest revision of the valve thats stronger than older versions.
It looks like this:
oe_d_valve_300x185.jpg
.
 

FactionOne

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The one VAGParts sell (interestingly they call it a Dump Valve too, despite as HTC has excellently illustrated, it actually being a diverter valve) is listed as part number 06A145710N; in Audi's own words, that's a cut-off valve; so your dealership's service department are still technically mis-informed /ubbthreads/images/graemlins/lol.gif -edit: had a trip to the garage mid-post so didn't spot HTC had covered that one!

The one thing I can't help thinking though, is that when asked for information on a diverter valve, they didn't instantly know what you were on about, and suspected you might mean a dump valve. That would make me nervous, I wouldn't want anyone messing about with my charge system (when I have one!) who doesn't actually know how it works. I'd be ringing the switchboard number again and be asking to be put through to parts and doing the job myself if that's how clueless service are.

Just my 2p's...

Regards,

Rob.

edit: I'm not sure if I'm bang on right, but it might be worth getting on to VAGParts actually, although you'll probably wait a couple of days longer, because the prices I have say Audi want £21.18 plus a drink for Gordon and VAGParts are coming in at £15.41 plus the VAT. I dunno how carriage might sway it though...
 

madvw

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[ QUOTE ]

Some service people aren't very clever. ...they get a tad confused.


[/ QUOTE ]


/ubbthreads/images/graemlins/cry.gif /ubbthreads/images/graemlins/cry.gif /ubbthreads/images/graemlins/cry.gif /ubbthreads/images/graemlins/cry.gif /ubbthreads/images/graemlins/cry.gif

must be the understatement of the new year so far!
 

JB_A3_Turbo

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I've got a mechanic friend who works for VW who I asked yesterday about this problem. He understood immediately what I was talking about!

He's going to take it for a spin and see what he reckons- he's also bringing a replacement DV (cut-off valve) home tonight to fit for me.

Will see how it goes!
 

JB_A3_Turbo

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Yes the DV was broke. It was looked at and tested with a vacuum testing bit of kit. This revealed it was unable to hold a vacuum as it should. Getting it replaced on wed since they didn't have the bit's in. So will be interesting to see if I notice a power difference with it fitted!
 

C_Audiboy

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Excellent post HTC - a very clear explanation and good diagrams.

I'm a total monkey when it comes to 'techie' stuff on cars but even I understand this process now!!

Good work /ubbthreads/images/graemlins/bravo.gif
 

JB_A3_Turbo

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I was suprised if my DV was not holding a vacuum that the car and turbo worked at?!?! Apparently the escaping air through the valve will be sending a shockwave into the turbo and cause "turbo stall".
 

JB_A3_Turbo

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OK....the DV has been replaced....but I'm still getting the noise!!!! The old DV was checked to see if it could hold a vacuum and it was not- so it was blatently broken. A new one (part number as above) has been fitted although an air rushing sound can be heard when lifting off the throttle. We've not tested the new DV to check that this is holding a vacuum now. Accelaration seems pretty rapid to me plenty of grunt when you put your foot down at at 2000, 3000 , 4000rpm.

Although I understand that the DV is sending the excess air through the cars internals (as opposed to the atmospehere- which would make a noise) I'm told that I shouldn't be hearing any noise?- could it be the noise I'm hearing is the noise as it goes through the internals? If that's the case was my DV ever broken in the first place?- it looks like it wasn't working as it should.

/ubbthreads/images/graemlins/noidea.gif

Any suggestions?

thanks
 

HTC

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With a working valve you will often hear a little noise. This is normal. The "fluttering" type noise should have gone tho, if that makes sense.
 

starski4578

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Its normal to hear the DV when you let off the pedal especially at high revs and in built up areas. If its been chipped it will be even more noticable. So long as the fluttering noise has gone away im sure its working fine.
 

A3TDI_SPORT

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Hi all, i am new to this forum. I bought a A3 TDI Sport a week ago from an Audi dealer. I have exactly the same symptoms as described above, do you think this will be covered under the warranty, or do you think i will be better coming from the 30 day Audi exchange angle?

Cheers!
 

Timbo

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A3TDI_SPORT said:
Hi all, i am new to this forum. I bought a A3 TDI Sport a week ago from an Audi dealer. I have exactly the same symptoms as described above, do you think this will be covered under the warranty, or do you think i will be better coming from the 30 day Audi exchange angle?

Cheers!
AFAIK (and someone may correct me) TDI engines don't have diverter valves as they don't have throttles. So it's unlikely to be the same problem.
 
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