Turbo cut off valve

While having a couple of warranty items looked at (driver's seat belt & sun roof), I'd started having some trouble with a flat spot under medium to hard throttle. The car would accelerate as normal, but at 3000/3200 rpm there is a pronounced flat spot - as if you'd suddenly backed off or as if a plug has suddenly fouled. As the revs rise through to about 3500, the problem would quickly disappear with the revs quickly spinning up as normal.

The local dealer kept wanting to diagnose it as a DSG fault, even though I pointed out that it happened in various gears, or when a gear is held (ie nothing to do with the gear change).

They eventually pronounced it as a turbo cut off valve. The part will be fitted next week for a total cost of $255.60 (the car's out of warranty now).

Has anyone else had a similar problem or a problem with the cut off valve?

What seems peculiar is that the cut off valve (if playing up) at 3000 rpm should be associated with the supercharger, wouldn't it? I mean, at those revs the supercharger is handing boost over to the turbo and would need a cut off valve to help with this, wouldn't it?

G'day Barney, I'm very interested to see what the outcome is.
In the range from 2400-3500rpm both turbo and s/charger are boosting which obviously has a number of valves and senders in operation to control boost levels, the main valves are as follows:

Regulating Flap J808 - Supercharger bypass valve
Turbo Recirc Valve - N249
Solenoid Valve N75 - Turbo Charge Pressure control valve

I understand that the N75 valves are widely used in various roles on VAG vehicles and failures are not uncommon and the price sounds about right too - this is the turbo charge pressure control valve.

Let me know if you don't have a copy of the TSI Self Study manual (thank you Mr Greg Roles!!) and I can host it somewhere for download.

subscribed for future updates.

cheers,

Paul

Hi Paul

Thanks for the feedback! Yep, I have the Self Study Manual (Greg's a real prince, isn't he? :headbang and wondered which valve they were on about. The guy at Service was not a lot of help in being really informative (about half of them are clueless, the other half are OK). :frown:

Hopefully I'll be more enlightened next week and I'll post the results. Noticed that the average fuel economy was waaaaaaay up when I collected it - they sure road tested it (despite me taking the head mechanic for a 2 spins prior to dropping it off). Good in one way I s'pose... at least they were looking.

Strange though that the diagnostic gear couldn't pick it up, despite being able to pick up some really minor faults elsewhere :iono: VAGcom's both brilliant & dumb at the same time it seems.

To be continued...

OK, so I have the GT back from the stealers.
The part they replaced is part # 03C145710D.
Service were clueless as to exactly what part this is, so I went hunting.

Seems it's the N249 Turbocharger Air Recirculation Valve.
Upside: quote was $5 higher than what I had to pay, and the car was ready before they promised (will wonders ever cease?).
Part was $98.46, labour $131.25. Time to fit ~1 hour.

Found quite a few references to this part on the Web, some of the links are below:

http://translate.google.com.au/tran...&hl=en&safe=off&biw=1915&bih=1305&prmd=ivnsfd

http://www.volksnation.com.mo/forum/archiver/?tid-91.html

http://vorsicht.org.hk/forums/showthread.php?t=11414

http://uk-mkivs.net/forums/p/397693/2733587.aspx

Below is a photo of the part in situ (ie under my hood) - apologies for the dodgey pic. Instructions on how to remove the engine cover were found in the installation instructions.

PS This is the part you'd remove the put the Forge DV (tshhhhhhh, tshhhhhh!) Atmospheric Blow-Off adapter valve in place. Instructions on how to remove the engine cover were found in the installation instructions for the Forge Valve.

Hope this helps the rest of you when you get a giant flat spot at 3200 rpm. Keep an eye on the boost gauge at the time of the event - it'll drop like a rock.
Off topic - this is the first real use for that gauge I have encountered (other than the obvious Colour & Movement Effect, of course!).

OK - an update.

While the car is slightly better, the lack of boost is still happening.
Hit ~3000 rpm in any gear and the needle on the boost gauge drops to about 1/4 to 1/3.
:mad0259:
The stealer appeared non-plussed by my reappearance (poor things!).
I now have to lose the car for "at least a full day, maybe more" while they reassess - yet again.
This will be the fourth time someone's taken a look at it.

Can't work out how a road test after 'fixing' wouldn't have shown this up.
Their excuse is that they don't "drive customer's cars that hard".

Doesn't wash with me, as the condition occurs at a particular rev range - not at a particular speed.
Why not for example, hold the damn thing in 2nd (~40kph) or even 3rd (~55kph)?
You don't need to break the speed limit to induce the condition. Or stick it on a dyno even...

They did hint at the fact that the replaced part was something that VW are 'aware' of.
Seems to me they looked up what it MAY LIKELY be, and just plonked that part in it.

Also said they don't have too much experience with my motor.
GTs outnumbered GTIs in the car park 3:1, and besides what are they going to do when a mainstream Mk6 TSI comes in?
Consult the Ouija Board, I s'pose...

The implication was also that I drive the thing much harder than normal (not true).
a) none of their business
b) what do I do when I put my foot down to pass a B-Double?
c) what's their diagnostic gear doing all this time?

Love the car, despise everything else. Will keep you posted.

Not all that happy, Jan...

Keep at 'em, they should know the car in and out and be able to support it!

hey

just had my turbo bypass valve replaced as it was faulty, they picked it up on the diagnose so i don't see how they couldn't find out your problem with the diagnose. It cost me 480 bucks. don't know if this helps but tought i'd let you know.

Jayo365 said:

...they picked it up on the diagnose so i don't see how they couldn't find out your problem with the diagnose

Click to expand...

I'm guessing because:
a) your guys actually did the diagnosis or
b) your guys knew how to read the diagnosis and
c) your guys probably road tested it too!
:yikes:

Thnx for the input - it will save me fainting when they finally quote me the correct part!

I think I have a similar problem with my car and was wondering if you managed to get it fixed ( what part was the culprit and how much was it to replace? )

Take it to a specialist rather the a VW service. I like the fact I talk to the guy working on the car rather than a service manager who keeps going out into workshop to get answers for questions I have. Someone must know of someone in Adelaide I'm guessing.

badboy said:

Take it to a specialist rather the a VW service. I like the fact I talk to the guy working on the car rather than a service manager who keeps going out into workshop to get answers for questions I have. Someone must know of someone in Adelaide I'm guessing.

Click to expand...

Yep you're right, however as I've already sunk money into the repairs, I really want to have them fix it properly this time - I'll be deducting the incorrect repair fee from the final bill. :fighting0030: