Just became an RS6 owner - a few questions on stage 0

[JCviggen]

Doesn't it need to be at least 2 things though?

Idle lean --> air must be sucked from the low pressure side so pre-turbo but post MAF or from the vac lines that are connected to the intake manifold.
Higher rpm rich --> air leak must be between turbo and intake manifold, possible IC or hoses.

There is only positive pressure after the turbo and only negative on the intake side so a leak in 1 of those places can only go 1 way not both..

[Shoppinit]

When the turbo is off boost then it's negative pressure. When it's on boost, then it's positive pressure. So a hole in your intercooler could blow both ways.

[JCviggen]

When the turbo is off boost then it's negative pressure. When it's on boost, then it's positive pressure. So a hole in your intercooler could blow both ways.

Hmmm no it isnt. Not to disagree but if you'd put a boost gauge in between the turbo and throttle body it never goes negative. Even cruising at a steady 3000rpm you would see a decent positive pressure. The only vacuum is in the intake manifold when the TB is nearly closed. The turbo is pushing air onto the throttle plate.
I've had boost gauges hooked up there on some of my cars when troubleshooting boost issues and it was quite surprising how much positive pressure a turbo makes while the engine is not really doing anything.

Thats why when you open the throttle your vac drops to 0 right away before the turbo has a chance to spool.

[Shoppinit]

OK. I see what you are saying.

Found this:

http://wiki.ross-tech.com/wiki/index.ph ... 136/004406

Could be related to your evap after all... Wouldn't hurt to start there if you can't find a vacuum leak.

[spurtle]

I still think you need to check the MAF seating.

+1. And my money is still on the lambdas. When you clear the DTCs, this will reset the fuel trims (they'll be relearned over 30 miles or so) - see if this improves fuel consumption or makes the idle more even.

[JCviggen]

Small update, after the dealer visit last week I've lost a few codes but sadly not too many of them. However the MIL has not gone on thus far the last 100 miles, before it would only take 20.

The EVAP fault is gone after replacing the purge valve. And after they checked and re-assembled the intake "no leaks found" I have also lost 1 of the lean idle codes and idle is a little better but not perfect. I checked with VCDS and 1 of the MAFs now reads 0.3 g/s higher at idle than the other (before they were the same) and the one still reading low is the side that has the lean code. So logically its still leaking there. I'll ask them to fix that, but I wouldn't be surprised if they don't have the rubber gaskets in stock and they take 2 weeks to get here. Or they might f*** up the other side again.

Both (mult) rich codes are still present as well. Could be the leaking intercoolers. Though whatever they are leaking can't be very much since the maximum airflow values through the MAFs are about what they should be. Both banks are in the same ballpark so I assume the MAFs are OK (or both equally wrong - less likely)
Also logged boost and it seems to peak around 0.7 bar but on average it's more like 0.6 - could be because of the very low temperatures that the ECU requests less boost to make the power it should.

It's a fairly normal -8C here at the moment and I have experienced no more battery or alternator issues at this point. Not sure that'll hold when we see -20 again but let's wait and see.

Gearbox code TC clutch stuck OFF came back, too. I think after flooring it a few times in 1st and 2nd and using the paddles. Car has 67k miles and as far as I can see the box has never been touched. So ATF quality and level are dubious. May have to go ahead and spend 550£ on an oil change with no certainty of success. That said the car drives normal enough, shifts OK, so if it doesn't go away I may just have to ignore it and see if it eventually grenades or not. The type of driving I do here the box spends 98% of the time not in lock-up anyway.

[Shoppinit]

Sometimes the contaminated ATF is all that holds the box together and when you change it that's when you start seeing problems. IMO it's better to change it, cross your fingers and deal with the consequences if any than to wait for it to explode, knowing that it's full of sludge.

Perhaps you've got a dodgy lambda sensor. Are they both reading the same voltage / correction?

IF both lambda probes are reading about the same then that would suggest something upstream of the intake manifold.

When is the last time the plugs were changed? And what plugs are you running? Is there anything in the misfire detector counter?

At this stage, I would change the MAFs just on general principals (if you haven't already, that is). Get some shipped in from a reputable source of genuine bosch units and change them yourself to be sure. I did a tutorial that can show you how to get at the MAFs in the stickies. You could consider changing the N75 and DVs while you're at it, if you feel like a bit of preventive maintenance.

[Shoppinit]

I checked with VCDS and 1 of the MAFs now reads 0.3 g/s higher at idle than the other (before they were the same)

They haven't seated them properly.

Do it yourself, it's the only way to be sure. It just feels right when you do it properly. If you have to force then they are not seated right.

[JCviggen]

The lambdas are reading fairly similar, I only checked while idling and the one with the idle lean code and less MAF was subtracting a bigger % than the other. But they were both in minus a few percent IIRC.

Plugs were changed 600 miles ago, OEM. No misfires detected.

I've been planning to go at the intake myself but freezing my butt off outside has so far kept me from trying. I also lack some tools and haven't found a ratchet yet in stores. Will have a look at your pics! The car is due back in service next week when the PS hoses arrive anyway.

If the box goes my relationship will probably go along with it lol, the g/f is near the limit of what she will accept being spent on the car rather than her
Quite amazing that she considers 1000+ pounds for a handbag acceptable, but 1000 in car maintenance is "ludicrous" "I could buy 2 pairs of shoes for that!!"

[JCviggen]

EVAP fault P0441 is back as well now, by the way. So that N80 valve wasn't exactly 200$ well spent. No clue how to explain to them in english with my gf translating that the problem can lie in the charcoal canister or in the lines. (flow lower limit exceeded guessing something's clogged up) They haven't got a clue what I'm on about. In fact they seem to be somewhat irritated by us telling them how to do their job Somewhat starting to regret buying a car for which no qualified service exists in this country.

[Shoppinit]

Welcome to the world of every RS6 owner outside of Germany and the UK. Incompetent bar stewards. I think you're gonna have to do it yourself. Or find a tame local garage guy and get them to follow instructions. I'd definitely change the carbon canister (as long as you're sure none of the vacuum pipes have perished).

Have you tried finding a specialist in Moscow? How about some of the surounding countries?

I would attempt to post on here to see if anyone can recommend anything. Perhaps your girlfriend can help you.

http://www.audi-club.ru/forum/showthread.php?t=213651

[JCviggen]

Thanks I was planning to register there and see if they have any russian wizards

Surrounding countries are not likely to be of much help, and western europe is a 3-day trip in each direction. I'd love to make it one day but I'm not sure i'd like to set off while there's as many things potentially wrong with the car.

Funny thing today, whilst correcting the clock in the dash by a minute or 2 I managed to inadvertently enable something that would make an annoying BEEP and display a yellow km/h sign whenever I went faster than 5 km/h. Thank god it was gone the next start because that drove me insane and I don't actually have an instruction manual for the car. There is such a thing as putting too many useless things on a car!

[monoi]

It happened to me, it is a limiter in that it tells you you're going faster than the speed you set, by mistake obviously.

I did it inadvertently trying to reset the miles and pressing the wrong button. I can check in the manual the exact procedure if you want.