Another item on my to do list could be to track down a boost leak. Almost every time I went to change gear you you could hear boost escaping, kind of like a chavi dump valve. Now my dump valve is standard (from the external look of it), but the vacuum pipe was very lose and just pulled off with ease. Now I don't believe that is was where the sound was coming from so anyone know where the most common place to find a boost leak, and why would I get it when I was changing gear?
Buying an S2 Coupe - Am I walking into a world of pain.
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Could be the diaphragm in the DV is split, you should be able to hold vacuum on the actuator line. An actual boost leak will woosh or whistle as the boost builds, not as you change gear.Another item on my to do list could be to track down a boost leak. Almost every time I went to change gear you you could hear boost escaping, kind of like a chavi dump valve. Now my dump valve is standard (from the external look of it), but the vacuum pipe was very lose and just pulled off with ease. Now I don't believe that is was where the sound was coming from so anyone know where the most common place to find a boost leak, and why would I get it when I was changing gear?
The DV is actually a Diverter Valve in the stock configuration as it doesn’t dump, it diverts manifold pressure back to the face of the turbo.
The plastic DV often rests on the back of the headlight surround and can rub through, I’ve seen plenty of these with a hole in them. Worth checking.
Does the car have the stock airbox with the stock paper filter? Cone filters sound noisy..Last edited by newsh; 25 October 2021, 17:17.Comment
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Great, the paper filter is perfectly adequate, I use one on my 400 hp car, although it’s in an RS2 airbox which flows a bit better.
People are weird with K&N filters, they don’t check them, I pulled one out of a bike that was threadbare, basically doing nothing, at least with a paper one, ok they get dirty and block up but they don’t stop filtering the air.Comment
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We fitted a panel K&N into our S2 ‘back in the day’ and it gummed up the MAF in about a month of normal driving. It was about the time several people on here saw a similar issue so we reverted to paper and gave the MAF an industrial alcohol bath. It might have been an ‘era’ issue but it put us off.
Great, the paper filter is perfectly adequate, I use one on my 400 hp car, although it’s in an RS2 airbox which flows a bit better.
People are weird with K&N filters, they don’t check them, I pulled one out of a bike that was threadbare, basically doing nothing, at least with a paper one, ok they get dirty and block up but they don’t stop filtering the air.85 WR Urquattro, 85 20vT International liveried RallyRep
93 MTMS2 Avant

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Hence the invention of the “MAF BAF”
We fitted a panel K&N into our S2 ‘back in the day’ and it gummed up the MAF in about a month of normal driving. It was about the time several people on here saw a similar issue so we reverted to paper and gave the MAF an industrial alcohol bath. It might have been an ‘era’ issue but it put us off.Comment
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Might have a Forge dump / recirc type valve they give you the woosh without affecting the running of the car, boost leaks are a nightmare to trace could be anywhere budAnother item on my to do list could be to track down a boost leak. Almost every time I went to change gear you you could hear boost escaping, kind of like a chavi dump valve. Now my dump valve is standard (from the external look of it), but the vacuum pipe was very lose and just pulled off with ease. Now I don't believe that is was where the sound was coming from so anyone know where the most common place to find a boost leak, and why would I get it when I was changing gear?Comment
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Did you try pulling a vacuum on the DV? Just pull the wee vac pipe off the front of the Inlet manifold and suck on it, (or use a mightyvac to avoid oily mouth lol).
You will definitely need to do a proper boost leak test. There’s a definitive thread on here about it but basically you pressurise the intake system from the MAF hose, it should hold about 1 Bar and leak down slowly past the rings and the turbo oil seals. You need a plug to fit the large end of the maf hose with a tyre valve in it. You can pressurise higher if you disconnect the PCV system from the maf hose.Comment
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So if I put a vacuum on the small pipe on the DV should it hold? As at the moment it does not hold any vacuum. I've also tried to push the valve in and hold my finger over the small pipe and as soon as you let go of the valve it just springs straight back,Comment
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Yes it should hold, the diaphragm is split and that accounts for your strange whooshy chav noise.
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Cool
710P is the uprated valve as fitted to the 1.8T.
If you need a spare, search “audi bosch 06a145710p” on eBay
You’ll probably only find aftermarket but Febi are ok I think someone said a Topran one worked but not sure how long it would last for £15.. your car is going to be running stock boost though so a good second had one should be fine.Comment
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Yes I have seen that but wanted to keep the Aux rad. One option would be to delete the air guide and try and mount a third party cooler where that guide used to be. Or bite the bullet & buy a replacement cooler from Germany, and make a replacement bracket.Comment
Will get the DV removed in the morning.
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