Can anyone help? I've got no boost

[Audi Parts Guru]

Gents,

My poor old girl has suddenly lost all of her boost. She's just passed the 200k miles mark and when I was driving home from work the other day, I put my foot down and suddenly no boost. She just seems to drive like a normally aspirated car for some reason

Now apart from checking hoses and vacuum pipes etc, what else do I need to check?

Any help would be much appreciated

Oh and there's no fault codes registered

[DarrenM]

You got a boost gauge, if so, whats it showing? The hose popped off the back of mine ages ago, i gained a hisss noise and lost boost..

[sheppardnias]

With a duff WGFV on my S6 the car drove very much like a normally aspirated car. Didn't feel much quicker than my old coupe which was a 2.6. No surge as the revs rose (I think that the .4 bar boost that the wastegate opens at is hit at pretty low revs), no ecu error codes just a reasonably paced estate car. That would be my first point of call, unless you can here a hiss from a leak.

Easy to check a WGFV with VagCom or with a 12V power source and a couple of wires onto the connection point. If it doesn't click, it's dead.

[andyg plym]

ever replaced the nock sensors?

[UrS4boy]

... I was driving home from work the other day, I put my foot down and suddenly no boost. She just seems to drive like a normally aspirated car for some reason Now apart from checking hoses and vacuum pipes etc, what else do I need to check? Any help would be much appreciated

Oh and there's no fault codes registered

This happens all the time on UrS4s. The boost signal hose to the ECU blows off the moisture trap on the firewall. This leaves you with just waste gate spring-based boost. (The ECU is not getting any signals to control the N75 WGFV). There are not fault codes generated. I presume your ABY S2 Avant has something similar. Check out the diagram at the link below. The moisture trap looks like a black 35 mm film can (or inline fuel filter):

http://forums.audiworld.com/s4s6/msgs/222453.phtml

Dave F.

[valjo]

also check MAF and lambda probe.

[Audi Parts Guru]

ever replaced the nock sensors?

Nope, all original and untouched

[220bhp]

Replaced everything on mine but it was the front knock sensor that made a real difference.

[Audi Parts Guru]

Replaced everything on mine but it was the front knock sensor that made a real difference.

Did you get a fault code from this?

[UrS4boy]

Did you get a fault code from this?

I wouldn't be chasing the knock sensor possibility until you make sure that the boost signal hose to the moisture trap and ECU is intact (check the clamps, etc.). Typically solved with a 50P gear clamp.

Dave F.

[S2central.net]

I'm with UrS4boy on this one... Or maybe a WGFV failure (or wiring to it - or its fuse)


Paul

[Audi Parts Guru]

I'm with UrS4boy on this one... Or maybe a WGFV failure (or wiring to it - or its fuse)


Paul

Any idea of the fuse number and size?

I'll check this tomorrow as well as the moisture trap hose

[Audi Parts Guru]

Gents, I'm about to go and check the pipes to and from the moisture trap on my car, but before I do can anyone let me know exactly where it is situated on an S2 Avant?

I've had a quick look but can't see anything

[europeanme]

have the same thing on my avant...my WGFV had a cracked pipe so I've just purchased a new WGFV from VAG parts and will fit it over this weekend, hopefully!?!?!...

[S2central.net]

I think the moisture trap is a red-herring but its in the passenger side A-pillar, behind a piece of trim - close to the altitude sensor.

DO the MOtronic output tests, pull codes etc - should point at WGFV if its gone open circuit... Else buy a new one - cheap as chips