ELEVENS

Doing another carbon clean, this time with only 12,000 miles. The carbon is much less than the first time (@33,000 miles), but still very substantial, mostly on the backsides of the valves. The vanes were not too bad at all this time. And the port walls weren't as bad either. The carbon was much softer this time, perhaps due to all the liquid crap I've been aspirating into the intake manifold. The job took 9 hours. The first time the carbon was much thicker, harder, and took 13 hours.

My 12,000 miles:

* Nothing but Shell V-Power 93 octane

* RLI BioSyn fuel conditioner, 25ml every fiillup

* Miscellaneous elixirs sucked through the Vijay port (an unused vacuum port on early 2007 cars) every 1000-1500 miles - SeaFoam, GM induction cleaner, BG ISC.

* BG MOA oil additive with Valvoline Platinum Euro 5W-40, 4000-mile oil change intervals.

I stand by my original prediction that this is something that needs to be done every 10,000-15,000 miles on this car. This time around, the flaps and vanes will be permanently removed. What a dirty pain in the ****! The car runs amazing now, expecially 5100-redline. It can finally breayth again as the designers intended.

Pictures here: http://pcvb.smugmug.com/STUFF/Carbon-buildup/21943882_SjB47R#!i=1750206867&k=j67TsVh

BEFORE


AFTER

aTOMic

What are the things in pic #3?

What engine in the RS4?

Searched your "garage" for the engine size, I guess mine doesn't say mine (yet) either.

Wow, what a mess! Great pics though.
Put some links to your cleaning procedure in this post! SCHNELL!



-Tom

ELEVENS

That 3rd pic is the intake manifold flaps. My theory on the purpose of the flaps is to increase air velocity at low rpm which promotes proper swirl inside the combustion chamber for complete fuel mixing. The flaps move out of the way at higher rps for increased flow.

The B7 RS4 has a 4.2L FSI V8 engine code BNS.

Sorry, I'm too lazy to do a how-to write up.

aTOMic

As much work as the engine disassembly was - dude, you are NOT lazy! I figured you had already done the writeup; but I was too lazy to search through your thousands of posts!

I am bookmarking the pics for the next time someone argues that "...modern gasoline has a full complement of detergents blah blah...ventil sauber is a waste of money...my engine is as clean as new inside...". People who hold this fantasy have never dismantled an engine.

I wonder how much of the buildup was oil vapor? Any chemists reading this, is there any analysis possible?
Sooo the RS4 is like my Passat, but with Quattro and with my A8's engine in it? Oooooh, me likey! I love the sound of the 4.2 V8, even though is's muffled/resonatored/silencered/catalyzed almost to complete silence!

Questions - 1) I cannot believe VAG would spend an extra nickel on something that was not essential to proper engine operation; after removing the flaps and vanes are there any ill effects?

2) Was the cleaning done
a)by just running solvents through or did you
b)scrub off the carbon?

Thanks,
Tom

ELEVENS

Yes the ill effect of removing the flaps is poor low-speed drivability and lowered fuel mileage. I wouldn't recommend it unless you're after those last couple of HP.

The carbon MUST be manually removed. I use a variety of dental tools and gun brushes. Soaking in a solvent helps soften up some, but not all, of the harder deposits, and also works to flush out the carbon bits using a turkey baster. Compressed air works great as a final step (port covered with a rag of course).

RS4Ship

ELEVENS - Just curious, but does your motor burn any oil in between changes?

I'm at about 15k+ miles since the last carbon clean, but I don't know if I want to tackle this on my own. I've read the DIY guides, and it doesn't look too difficult, just looks like everything takes a while. What made you decide not to take it to a shop to have this done? Have you had any issues or broken anything along the way.

ELEVENS

Nope, none at all. My motor stopped burning oil after break-in (around 10,000).

I've not broken anything along the way, other than the occasional hose clamp. I did it myself because I can. And because I'm curious to see how things work. And because I don't trust others working on my stuff. And last but not least, because I'm a cheap SOB.

s4master1

great job on the clean up.
have you considered 10w-50, 10w-60 oil?
just like the bmw m series oil, we use it on rs4s and consumption and carbon build up have minimize very noticeably.
we have cars going over 30k after cleaning and no deposits or at least nowhere near the ones in your pictures.
like to know the effects of removing the flaps completely.
careful with strong chemicals and cylinder walls.

to the A8 guy
Sooo the RS4 is like my Passat, but with Quattro and with my A8's engine in it? Oooooh, me likey! I love the sound of the 4.2 V8, even though is's muffled/resonatored/silencered/catalyzed almost to complete silence!

seriously?
like your passat?, a8 engine?
total insult to the RS4.

ELEVENS

Ahh the old 10W-60 BMW oil we used to run in our M5's. I thought about that, and I'm not surprised it would help with the carbon issue. But I'm not willing to give up the (5-10HP?) and (1mpg?) power and fuel economy loss that the extra viscosity oil would bring.

I'm also a little hesitant to move that far out of the range that the Audi engineers recommend for the motor (5W-40 or even 0W-40 for Mobile 1).

The effects of removing the flaps were not good (for me) when cold and running under 3000rpm. I plan to re-install the flaps very soon. It was a worthwhile experiment. I believe it boils down to how you use the car. If you drive it like you stole it and also don't give a hoot about fuel mileage, ditch the flaps. If you drive reasonably and spend a lot of time under 3000rpm, and like better fuel economy, keep the flaps.

About the harsh chemicals aspirated into the intake manifold.. I think I'm done with that experiment too. The wash patterns on the flaps and vanes show that the carbon-eating liquid elixirs really only make it into the closest intake trumpets. That makes sense when you think about it. The liquid's mass effects time of flight inside the IM plenum.

aTOMic

To the motorcycle guy,
I humbly explain that I meant no disrespect to the A4/S4/RS4 cars; on the contrary! I simply meant to compare the (most excellent) effect of taking a car the size of my Passat and stuffing it with a V8 and Quattro (like in my A8). If I somehow offended you I certainly did not intend to.
Regarding the 8 engine, I am currently trying to differentiate the Audi 4.2 (gas) V8s on this thread, so if you could please help me to understand the variations, I'd appreciate that! Are there many differences between the A8's 4.2 and the one in RS4s?
As for the silence of the engines, I love the soft growl of the A8. I wish it was louder, though! (Maybe Audi should do like BMW's "Active Sound System" (A.S.S.) or ASM or whatever they call it, and play a recording of a nice engine sound through the stereo! No, on second thought that'd be stupid). Anyway, one time I opened the A8's window while driving beside a building and stomped it - and I could not hear the engine as well as with the windows up! I guess the "normal" luxo-car buyer wants their car quiet, but I do not pretend to be normal.
Thanks for your input!
-Tom