Flapper Mod with Switch

Yannis

Yannis

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I have been doing some research on the flapper mod. I have found plenty of info for the R32 and TT but nothing for the A3.

I know the wire that I'm looking for is a 0.5mm grey with blue stripe. However in the guides that I have read, this wire seems to be located in different places depending on RHD or LHD, R32 or TT.

I am also having trouble gaining access to any of the possible locations due to all the trim that is hiding everything. Do I need to do something like this to gain access?

ImageUploadedByTapatalk1413886854393446


Where are all the relays hidden on a RHD 8P A3? Drivers side or Passenger side? I believe once I have access to these the location of my wire will become clear.
 
Ok, so I have just been out and taken off the A-Pillar bottom section on both drivers and passenger sides to reveal the wiring loom running to the back of the car.

On the drivers side there is no sign of a grey wire with blue stripe. But on the passenger side I have found one.

A few of the guides talk about there being 2 of these wires and you have to get the right one?

I can only see one so far but I haven't cut open the loom to have a real look. Once the parts arrive I will get stuck in and open up the loom and have a real search about.

If I do find two wires the same, I'm not really sure how to differentiate between them? Maybe I could go ahead and cut it then run a VAGCOM scan and see if I get the following;

1 Fault Found: 19475 - Valve for Exhaust Flap 1 (N321): Open Circuit P3019 - 004 - No Signal/Communications - Intermittent

I will do a step by step guide on this once I have figured it all out.
 
Potentially going to sound very thick here but what is the flapper mod?
 
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As Andy Parker says what,s the flapper mod :uhm: I can think of something quite filthy but i,m quite sure I,m wrong on that one lol......:undwech:
 
exhaust flap
 
Some cars have a vacuum / ECU operated "flap" in the exhaust tail pipe.
It is opened and closed at certain pre determined revs, speeds, gears , mostly to control noise etc. some cars like TTRS and also RS3 have a sport button that can influence the flap more, but still certain revs, speeds gears. When open on the RS there is a noticeable tone or volume difference, so much so, I think the second tail might take a less restrictive route through the back box internally.

Flapper mods vary from removing the pipe and sealing off, so 100% open to switchable on off, or standard,loud, quiet to fancy remote control, or extra vacuum valves that retain oem system, and provide an override Off function.

It was a real popular mod on R32's and has grown since.

I'm standard, with the factory sports button, and 100% on would do my head in, there are times where you just don't want the drone, like on motorways etc. This is where a switchable option comes in. There are loads and loads of different variants if you google switchable flapper mod.

I've looked into it, even found a relay board that I could be controlled with a iPhone. ( a first and a twist on the remote version that I haven't seen before) but I don't want to hack about my looms, and even if I could make it plug and play, I'm not sure I would want to pull my car apart to install it.

I'm creak and rattle free, and like it that way.
 
Ok this is new to me so the S3 has a exhaust flap ?

IE to make it loud under full throttle and quiet under part... ?
 
8P S3 yes.
8L S3 no.

All defined by the ECU, and controlled via vacuum.

Vacuum on flap closed
Vacuum off flap open
 
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Ah ok - had heard of it on the RS4 but not the S3 - I've got a full Milltek now so a bit redundant for me I think
 
There is one on my 3.2 sport , I looked into this mod too but sometimes it's nice to sneak about and not draw too much unwanted attention .................officer :busted cop:
 
I have the 3.2 and will be making a guide for this once all the parts arrive.

It will be switchable so if you don't want to draw attention to yourself, you can just flick the switch and it's back in OEM mode.

You can buy kits for the R32 which would work in the A3/S3 but they are only available in America for about $55. Considering the parts for doing this cost about a fiver I think I will manage without the kit.
 
So, managed to get a bit of time over the last few days to fit everything.

To check to see if it was all working correctly, I put the GoPro on the back of the car pointing at the flapper. Went up and down the road in both normal and loud mode and guess what, the flap doesn't move, It's just always open.

I am confident my wiring is sound and all connected up correctly to the right wire in the loom.

I have run a scan with VAGCOM to make sure I haven't got 19475 fault, I even unplugged my wiring and did another scan to see if the fault was triggered when the wire from the ECU was not connected to anything. And still nothing.

Can the flap position be read by looking at a block on VAGCOM?
 
Yannis said:
Can the flap position be read by looking at a block on VAGCOM?
Click to expand...

Not physically, it's a dumb electro mechanical movement.
You might be able to find/ monitor the Solenoid output N321 though if there is a measuring block.
 
I don't really understand why no fault was registered when I ran the car with the wire cut?

I'm not sure if the flap was actually working before I did the mod but I presume it was as VAGCOM a has never shown the flapper fault?

Any ideas?
 
If I ground the wire leading to the solenoid it should shut the flap?
 
That's how I understand it

From that German link I sent you....

The solenoid valve is energized via a black / green wire directly from terminal 15 (ignition + 12V..14V).
The ground wire of the solenoid valve is fed back via a brown / purple wire to the engine control unit.
Click to expand...
 
Ok, so I have come to a bit of a dead end....

This morning I started from the flapper itself and worked back to check everything was actually working correctly.

I ran the engine to build up a vacuum in the reservoir. I shut off the engine and then took the vacuum line of the reservoir and heard a good whoosh as the air rushed in.

So there is a vacuum!

Next I gave a suck on the pipe to the flapper and sure enough it shut nice and easily.

So the flapper mechanism works.

I then unhooked the solenoid that governs the vacuum supply. Rigged it up to a 12v supply and it worked as expected.

So everything at the back of the car is in good order.

Before I plugged the solenoid back in I put a voltage tester across the supply and tried my flapper switch to see if there was any reading. Nothing!

I even grounded the solenoid return to the ECU as per the guides to force it to close and still no reading.

So it seems my problem is that there is no 12v supply to the solenoid. Maybe I have blown a fuse in the wiring process?

Where does N321 get its 12v supply? Is it on constant supply and the ECU is in control of the ground side of things? This is what it would seem from the guides.

Has anyone got a wiring diagram for the 3.2?

Any suggestions would be great!
 
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