"Carbon build-up"

[Andyuk911]

PP,

must last word, a thread to all the other threads on the internet, DON'T get hung up on carbon... !

http://www.audizine.com/forum/showth...ad-for-RS4-4.2

If you want Audi's thoughts, pm Mr Q ... love to hear how different piston rings stop this ...

[Sims]

PP,

must last word, a thread to all the other threads on the internet, DON'T get hung up on carbon... !

http://www.audizine.com/forum/showth...ad-for-RS4-4.2

Thanks Andyuk911.

Someone has checked on ETKA and it seems the piston rings post CW20/2007 are not different.

Cheers

[DHall1]

I dont pop over here very often but noticed Qisha had a few notes.

This carbon situation in the US models was the #1 reason I didnt buy the RS4 or R8. After looking at some intake valves of low mileage cars and the current "fix" to clean them out....I passed on the entire idea. I will keep my RS6 than you very much.

Is it still true that the US models have a bigger problem than euro?

US gas is crap. Even the Shell premium. Our oils are not much better which is why Audi, BMW and Benz all specify certain oils.

Has anyone looked into BND oils and fuel conditioners? The guy is a chemical engineer and puts out a fantastic product. Many of us on the RS6 side use his oils and Aces IV fuel conditioner. I dont make a penny from this but if I had an RS4 in the US.....I would be giving his fuels and oils a consideration. Google BND auto and give Brian a call. You will be amazed.

Good luck with the solution guys.

Dear Friends,

as promised, i would like to say a word or two concerning „Carbon build-up“:

What is “Carbon build-up” and how does it come into being:

With fuel direct injection the cylinder heads and valves are no longer “washed” by fuel, which leads to a lacking “cleaning factor”. This is where the exhaust gas recirculation combined with the ventilation vapor of the crankcase ventilation and oil starts to build up. Particles of dirt and jets of water coming through the air intake path form into firmly adhering layer. This layer is taken up within the chambers of the cylinder heads and the admission valves, resulting in a rough surface, the airflow cross-sections become more narrow leading to non optimal air interlacing and cylinder charge. In total the results of “Carbon build-up” can be bad exhaust emissions, lower power output and higher consumption. In worst case the “Carbon build-up” affects the valve train. The valves can not close completely, which leads to low compression on the relevant cylinder, the fuel composition is not “fired”.

Factors that promote “Carbon build-up”:

Low quality fuel

Frequent short range driving

Preventing higher engine temps

Low RPM driving

intermittent driving

long time „not-using“

using non-specific engine oil


Audi RS 5 and „Carbon build-up“, do i have to worry?

As you might already know, the RS 5 engine ist based on the RS 4 V8 version. Main “Carbon build-up” relevant points that have been altered:

Engine production tolerance over again significant improved

Engine oil temp is increased by ~10°C

Modified piston rings


Resume:

The probability of „Carbon build-up“ within the RS 5 engine is nominal.

Qisha

PS: as the RS 4 V8 was also mentioned you migh like to note, that the engines from build date CW20/2007 received a altered cylinder head with different piston rings.

[MihokS5]

It seems that "carbon" is not really the issue because it is normal on all cars/DI cars, you will have to have it manually cleaned at some point.
The problem I see with the Audi FSI's is that large amount of oil consumption leading to sticky droplets building up on the valves. Can anyone enlighten me on this???

[Sims]

It seems that "carbon" is not really the issue because it is normal on all cars/DI cars, you will have to have it manually cleaned at some point.
The problem I see with the Audi FSI's is that large amount of oil consumption leading to sticky droplets building up on the valves. Can anyone enlighten me on this???

Here is one that was cleaned, and the result after 1300 miles.
http://www.tt-forum.co.uk/forum/view...ad1b&start=165

What does it effect - power, fuel/oil consumption? Anyone care to comment?

[DHall1]

Looks like time for a buy back.

I would stuff that car so far down Audi pants....they would never find it.

Here is one that was cleaned, and the result after 1300 miles.
http://www.tt-forum.co.uk/forum/view...ad1b&start=165

What does it effect - power, fuel/oil consumption? Anyone care to comment?

[Sims]

Looks like time for a buy back.

I would stuff that car so far down Audi pants....they would never find it.

I can sympathise with what you say, but what if it does not affect the power or the fuel consumption, and it's merely cosmetic as some people seem to think??

[Tanner]

I can sympathise with what you say, but what if it does not affect the power or the fuel consumption, and it's merely cosmetic as some people seem to think??

It does affect power. Couple guys on quattroworld.com dyno'ed their RS4 before and after the cleaning and there's a difference in the charts and such. I've always wondered about measuring something like the MAF before and after to see if that could be used to determine how bad the buildup *could* be without trying to put a boroscope through the intake (I tried on my 2.0T and the end of the scope kept on getting covered in oil).

[Sims]

It does affect power. Couple guys on quattroworld.com dyno'ed their RS4 before and after the cleaning and there's a difference in the charts and such. I've always wondered about measuring something like the MAF before and after to see if that could be used to determine how bad the buildup *could* be without trying to put a boroscope through the intake (I tried on my 2.0T and the end of the scope kept on getting covered in oil).

Clearly there are different opinions and experience. May I please have a link to the thread you mention about the before & after cleaning?

[PetrolDave]

My car is production June 2006.I am very concerned about carbon build-up.I have now 90.000 km.I drive once in a week for 200 km journey at least.Rear brakes are stock, but front after 3 times pad replacement are ceramics six months now.Average consumption 15 l/100km.4 sets of summer tires until now.No track use,Many times aggressive driving until speed limiter.

Is the performance of your car significantly worse now than when it was new?

Yes, then you need to have the cause investigated and not just assume it is due to carbon build up.

No, then why be concerned?

[KK265]

Is the performance of your car significantly worse now than when it was new?

Yes, then you need to have the cause investigated and not just assume it is due to carbon build up.

No, then why be concerned?

I do not feel any significant difference about performance.Only little bit vibration more on idle and at 2500 rpm from engine.But I do not like the pictures I see from other users with problems.So I am concerned.

[Tanner]

Clearly there are different opinions and experience. May I please have a link to the thread you mention about the before & after cleaning?

I don't have the links but the discussion is on http://forums.quattroworld.com/rs4b7/

[KK265]

Piston damage:http://www.youtube.com/watch?v=n7I4O...eature=related

[DHall1]

cosmetic holes in pistons? any other questions.

[Marv]

This might sound like a silly question (but that's never stopped me before )...

All modern diesel engines are direct injection and presumably suffer the same exhaust gas recirculation and piston ring leak issues - do they not also suffer carbon build up?

[MR USER]

My RS4 has now 94k km. I brought it in last week to have few things checked and all 4 brakes replaced.
One of the tests I asked Adi to carry out is cilinder compression. THe results were surprisingly good! However most of the km I did no my car were on stretches of 3-4 hundred Km at time and using the full rev band... In toher words the engine was properly used. However while talking to a friend thta owns a very large dealership in Italy I learned that few of his clients complained about loss of power. What he did is cleaning the manifolds (i guess that is the right name... I'm referring to the pipes attached to the engine that get the exahust gasses out of the cylinders). He noted a large build up of particles that were reducing significantly the diameter thus reducing the flow of gasses out of the engine. The result he mentioned is a gain of about 80 bhp... I'm no expert and for as much as it make sense cleaning the manifolds the power gain seems axaggerated.... moreover it takes 4 hours to clean them and another 10 to take the engine down.... so the total price could be very very high!

Any comments on that? Would you reccomend doing such work?

[GEN XER]

This was also addressed here. I actually put most of these questions to BND Auto and you can read his answers here.

http://www.rs6.com/showthread.php/17...in-our-engines

[GEN XER]

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