problems with boost @3k rpm + fluttering on/off/on..

[avants2turbo]

bit of history..

driving the car a couple of months ago, very occasionally i would get a hessitation when the car came onto boost (WOT), then it would clear and wouldnt do it again for a couple of journeys, this has been getting more frequent over the past month, to the point where it would do it 2-3 out of 4 times i put my foot down. I then had the main radiator crack on me, and have a devil of a job trying to get the Hella one from GSF instead of paying Audi £220+VAT. Got the radiator finally friday, and fitted it yesterday (3 hours to remove and refit.. was quiet chuffed) At the same time i bought new Bosch F5DPOR plugs and fitted them (incase the hessitation was down to something silly like the plugs) toop it for a spin earlier today, same problem as befor, and now it does it every time you put your foot down (WOT) in every gear, seems to come on at about 3k rpm.

The problem itself is @3k+ rpm (ish) and its like theres a flutter on the boost, its all jerky, not smooth at all

Im running the Apikol Ignition system that uses the 1.8T coils (06B 905 115R) and have the MTM remap from QST

I had a boost leak test done a few months back, and that was fine, but that was a few months back.

to me it feels a bit more like something opening and closing and loosing boost.

It was suggested to me that it could be the a dodgy coil, but it feels more like a mechanical problem, is there anyway i can test the 1.8T coils used in this ignition system?

Could it be something to do with the boost control (WGFV)? what does the WGFV do? and how can i check if its functioning correctly?

can i disconnect it and see if theres any improvement with mechanical boost? if so what do i disconnect? where is the WGFV, whats it look like?

any other suggestions?

many thanks in advance
Keith

[Smith_S2]

Keith sounds like what i had read this

http://www.s2forum.com/forum/showthread.php?t=32808

change your diaphragm if you can

[avants2turbo]

Keith sounds like what i had read this

http://www.s2forum.com/forum/showthread.php?t=32808

change your diaphragm if you can

how do i change the diaphragm? in what the wastgate?

do you get the part from Audi? part no.? pictures?

[Smith_S2]

It's so easy

http://www.sjmautotechnik.com/parts_products/wginst.html#wgdiainstall

part no N 90254601 that's what i got from Audi.

see pic attached for help use a 11mm socket.

HTH

[avants2turbo]

It's so easy

http://www.sjmautotechnik.com/parts_products/wginst.html#wgdiainstall

part no N 90254601 that's what i got from Audi.

see pic attached for help use a 11mm socket.

HTH

that picture is presumably after removing the top of the wastegate where i would assume theres a spring?

any ideas how much the diaphragm should be?

was your ripped or were there any obvious signs of damage ?

[merlin's S4]

Get yourself a new 1.8t coilpack (£20ish) and try it on each cylinder in turn and see if you can make the problem go away.

[Smith_S2]

Yes. Ripped, looked like a used condom , may be a bit harsh.

£40-£50 roughly

when you remove the WG cap(six small nuts) apply some pressure to the WG when you get to the last 3 nuts this will stop the WG from hitting you in the face, the rest will make perfect sense!

cheers
John

[avants2turbo]

Get yourself a new 1.8t coilpack (£20ish) and try it on each cylinder in turn and see if you can make the problem go away.

I have bought a new one, havent tried it yet, does it sound like a problem with the coilpack?

[avants2turbo]

Yes. Ripped, looked like a used condom , may be a bit harsh.

£40-£50 roughly

when you remove the WG cap(six small nuts) apply some pressure to the WG when you get to the last 3 nuts this will stop the WG from hitting you in the face, the rest will make perfect sense!

cheers
John

ill give the coilpack a go first as ive already bought this part and if that fails the Diaphragm is next on the list..

[bigdan]

hi there!

keep us posted, as i am having similar problems and would be really interested in the outcome

it seems to only happen when hot and i get the same fluttering on and off boost as you mentioned, sometimes she starts to boost and then dumps, or wont boost at all.
it may be interesting to note that mine is unmodified, except for an air filter?

[avants2turbo]

just had a call from Audi, my wastegate diaphragm has arrived, will pick it up in the morning and fit it, see if it fixes my problem.. knowing my luck it wont have!

[avants2turbo]

infact, i cant be arsed with this work lark, think ill knock it on the head at lunch time today and go get this done!

[Rusty]

What DV are you running? If it's an OE Bosch or 710N then they wear out over time. Cheap at £15 for a 710N.

[avants2turbo]

What DV are you running? If it's an OE Bosch or 710N then they wear out over time. Cheap at £15 for a 710N.

any ideas on the part no. for it?

[Rusty]

I've got a spare in the glvoebox, will have a look when I go outside in a bit. It's the DV from an S3 (or any 1.8T?) more commonly referred to as a 710N as that's the last digits. Other options are Forge DV007, Bailey, Turbosmart, GFB, best stick to recirculating type. If the DV is leaking then it'll be letting high pressure air back into the low pressure side and could give the problems ou describe. Worth replacing it if you've not ever done so. Other option is the Lambda probe, they can give some funnies but not as bad as you describe.

Oh, and if you've not got a method of leak testing the inlet then get yourself a kit (not sure if AndyP is still doing them) as that'll find you all the little leaks that kill performance over time. All the small bore hoses that relay boost all over the place degrade, and it's so easy to get a Jubilee clip on slightly on the P and get a leak that way.