Jenner

I am pretty sure this is due to the economy and the dealership is trying to make a few extra $ on the side but I figured I'd toss this out there to see if anyone else knows of carbon isuess with the RS4.

I am a little paranoid about carbon build up because the E39 M5 that my RS4 replaced was known to have issues(mine never did) and my 993 Turbo is also known to have carbon build up issues and can be a costly repair(again mine hasn't had this issue yet).

Anyhow the tech said that because of the currently quality of gas in the US and because of the way FSI works my valves are covered in tar like gunk and that he has pictures to show me(how the fack will I know the difference in pics between my valves and some other valves unless it has a time/date stamp on it which still could be faked).

So he says they have put some chemical on the valves now to loosen the crap and that while it should help out some, they also have this new forced chemical treatment system that is meant for FSI cars to clean out the carbon build up for $170.

For reference I have ~11,000 miles and only use Sunoco or Shell or Chevron 93 octane gas in my cars.

Can there be any truth to this? That there is excessive carbon build up due to no fuel washing over the valves and intake manifold like in sequential electronic port injection motors?

The second reason I think this is a scam is that he told me they also got a new nitrogen machine and want to fill my tires with nitrogen for $50. I said I would pass on the nitrogen and get back to him on the carbon removal treatment.

What do you guys think? 100% snake oil? Any truth to this? I guess I am just overly paranoid about this due to my knowledge of carbon build up in other engines and the problems it causes with performance and emmissions and CELs.

daveak05

Not "snake oil", he's not BS'ng you.

It's similar if not the same as the dealer fuel system cleaning where it's hooked up to an IV like device and cleans injectors and upper valves.

You can accomplish the same thing over time with use of a fuel system cleaner once every few months if you want. But the IV method is a thorough and quick method.

Nitrogen in tires is worth it too, IMO. Keeps pressure loss to almost non existent.

Redfoot

For $50?... Nitrogen? ...Seriously?

McQueen993

I have followed the Porsche issues for a while as I am a 993 owner. The issue with the 993 is failing inspection due to the CEL coming on as the carbon clogs the SAI ports. I have spoken to a mech I trust who calls BS on the regular SAI cleansing procedure as by the time the system is clogged, the valves will need replacement anyway (a flaw in the 993 engine), so the cost isn't worth it. There is also no noticable degradation in performance. I also didn't think this was an issue with the 993tt (you should look into this as you're a lucky tt owner).

Which leads to the RS4. My sense is that if you plan on keeping it forever, then clean it. If not, it's a waste of money. I don't think there will be (and hope there will not be) a comparable issue with the CEL and inspection issues with the RS4 since it's not emissions related.

Nitrogen - I guess I'd try it and see what happens. Ask to see the machine.

greatwhiteshark

its effectiveness over time, but it does minimize pressure loss. It also claims to prevent rust since there's no water in nitrogen.

CanuckRS4

1. on a new vehicle there is very little deposition especially if you use the high quality fuel with good detergents in them. ie. Shell V-power.
2. N2 for $50 is ridiculous, remember that normal air contains 79% nitrogen. Save your money.

greatwhiteshark

during several early production batches, or so I thought.

The argument about the valves on non DI fuel-injected engines does have some merit, I suppose, but what's to prevent 'carbon' from building/accumulating onto the tops of the exhaust valves, since fuel only sprays onto the intake valves?

CanuckRS4

There is no water in Oxygen either, which is O2. That statement makes no sense. Of course there is water in the atmosphere, it's called humidity for lack of a better layman word.
You're getting your noodle yanked pretty good if you buy Nitrogen for your tire fill-ups. But this kind of thing keeps the economy rolling i guess

greatwhiteshark

http://www.getnitrogen.org/why/index.php

Jenner

I'm perfectly happy monitoring/correcting my tires pressure myself with my gauge and air compressor and have the TPMS as a backup.

It's the carbon issue that I'm more confused about.

I must admit he had a good sales pitch with the bits about FSI and crappy gas in the US but the parts that really bother me are the fact that they "just got this new machine in for this specific purpose" and that my car has low mileage and only drinks top tier premium fuel.

His suggestion was to do this every 10,000 miles. I questioned why Audi would have engines with this "issue" but not cover it or mention it in the warranty or maintenance info. His reply was that they design their engines for European fuel not US.

Is there really that big of a quality difference between 93 PON USA and 95 MON Euro petrol? According to octane charts 93 PON is equal to 96 MON.