Audi TT removing mods from previous owner

[andymc]

Hi all, I have just taken in as a part exchange a 2002 Audi TT that's had a few mods, better filter, SS exhaust and a remap, the issue is the dump valve, its noisy as fk and will scare people off, can it be removed/blanked or would it need setting up again?

thanks
Andy

[V8RX7]

Some are adjustable to be quieter.

However you can replace it without issue - the air recirculates rather than being dumped - doesn't affect mapping.

[andymc]

V8RX7 said:

Some are adjustable to be quieter.

However you can replace it without issue - the air recirculates rather than being dumped - doesn't affect mapping.

ok, will look into it, cheers

[andymc]

V8RX7 said:

Some are adjustable to be quieter.

However you can replace it without issue - the air recirculates rather than being dumped - doesn't affect mapping.

so do i remove and then blank off?

[anonymous-user]

andymc said:

so do i remove and then blank off?

you can't blank off a dump valve, replace it with standard affair.

[V8RX7]

Get on a TT forum and find someone to swap - they will probably give you £40 too.

[jonwm]

I've got a standard one off a mk1 leon cupra r, if the tt is the 225 bhp model with the bam engine I'll try and find it for you, I sold mine with a repacement non noisy one

[jonwm]

Just re read and as it's mapped you'll not want the standard one, Google forge 007p that's what mine had on a was still silent just uprated to deal with the boost better,the standard ones diaphragm isn't strong enough and will fail, car will keep going into limp home mode.

[Ozzie Osmond]

... demonstrating once again that "modifications" are often a backwards step.

[jonwm]

Mine wasn't mapped, probably the only one that wasn't :-) I believe the original design was weak on the diverter valve,lots about it on the vag forums, only affected the 1.8t

[Slow]

Ozzie Osmond said:

... demonstrating once again that "modifications" are often a backwards step.

For the dealer taking the px, the person who owned the car probably liked it?

[GC8]

The Spruce goose said:

andymc said:

so do i remove and then blank off?

you can't blank off a dump valve, replace it with standard affair.

You can, but it will attempt to stall the turbo and increase lag, which is the exact opposite of what a recirculating air bypass valve was fitted for in the first place.

OP: re-fit the original recirculating bypass valve (nb 'dump valve' is a really lame misname).

[Coatesy351]

GC8 said:

You can, but it will attempt to stall the turbo

Urban myth. You cant stall or make a turbo spin backwards by not having a diverter valve fitted.

[anonymous-user]

Replacing the filter with a standard airbox will go along way to quieting the dump sound. A standard diverter valve is about £40 from the dealers which will get rid of any residual noise

[GC8]

Coatesy351 said:

GC8 said:

You can, but it will attempt to stall the turbo

Urban myth. You cant stall or make a turbo spin backwards by not having a diverter valve fitted.

Why are forums full of this? With 23yrs of turbocharged car ownership behind me I can assure you that I understand exactly how a turbocharger works both with and without a bypass valve.

Tell me Turbo-Guru, what do you think happens when you remove the air bypass valve, and why do you think that the development engineers fitted it in the first place?

Your attempt at forum wisdom is about as worthwhile as "there's no such thing as 'wastegate chatter' ".

[George111]

Most of the so called "premium" diverter valves perform worse than the stock part. On the 225bhp engine Audi used the same diverter valve Porsche used on the 911 (where there are two) - made by Bosch and back then cost £30 each.

[e635815]

On diesel engines, you will only find a wastegate (on non-variable geometry turbos) which dumps the exhaust gases directly into the pipe when the flow is too big for the turbo to handle (i.e. max rpm).

On gasoline engines, you find both the wastegate and the recirculation valve. The wastegate has the same function as on the diesel engine. The recirculation valve, recirculates the compressed air between compressor inlet and outlet when the throttle gets shut. This prevents the compressor from stalling and damaging the thrust bearing.

Now, which of those two systems is the OP talking about?
Both can be altered by aftermarket items with strong consequences on the long term reliability.
And both can, should be reverted back to original settings.

[GC8]

I doubt that he would be talking about the wastegate, even if he wasnt obviously talking about the air bypass valve, because wastegates are virtually always incorporated into turbochargers...

[Coatesy351]

GC8 said:

Why are forums full of this? With 23yrs of turbocharged car ownership behind me I can assure you that I understand exactly how a turbocharger works both with and without a bypass valve.

Tell me Turbo-Guru, what do you think happens when you remove the air bypass valve, and why do you think that the development engineers fitted it in the first place?

Your attempt at forum wisdom is about as worthwhile as "there's no such thing as 'wastegate chatter' ".

So educate me if you know it all what will happen to the car with it removed?