Another s6 carbon problem...
02-14-2011, 11:53 AM
#11
AudiWorld Member
This is a problem with engines where the fuel is directly injected into the cylinder.
Older engines would inject fuel in the intake manifold where it would clean the backside of the intake valves on it's way into the cylinder.
Without the cleaning action of the fuel, trace amounts of oil in the EGR system turn into varnish on the valves, which in turn absorbs carbon residue.
The end result is gunked up intake valves and surrounding area, that has to be manually cleaned by disassembly, or by seafoam or similar treatments.
02-14-2011, 12:54 PM
#12
2nd.
Why would you try something that doesn't reach the problem area?
This is a problem with engines where the fuel is directly injected into the cylinder.
Older engines would inject fuel in the intake manifold where it would clean the backside of the intake valves on it's way into the cylinder.
Without the cleaning action of the fuel, trace amounts of oil in the EGR system turn into varnish on the valves, which in turn absorbs carbon residue.
The end result is gunked up intake valves and surrounding area, that has to be manually cleaned by disassembly, or by seafoam or similar treatments.
This is a problem with engines where the fuel is directly injected into the cylinder.
Older engines would inject fuel in the intake manifold where it would clean the backside of the intake valves on it's way into the cylinder.
Without the cleaning action of the fuel, trace amounts of oil in the EGR system turn into varnish on the valves, which in turn absorbs carbon residue.
The end result is gunked up intake valves and surrounding area, that has to be manually cleaned by disassembly, or by seafoam or similar treatments.
02-14-2011, 12:59 PM
#13
AudiWorld Super User
Audi's argument is that some fuel still reaches the backs of the intake valves during the injection cycle (or even during valve overlap) and the regular amount of additives in the fuel is not enough since, as you pointed out, the valves are not completely washed over with fuel.
Although this is no excuse for a poor design it is the excuse they give and Audi's own software update for this issue modifies valve timing to combat the problem. (But some claim to still have the issue after the software update.)
Audi adamantly denies it has anything to do with oil and some who have used catch cans and such still report the problem.
Also heating the valves to the extreme is listed in the early DI tech documents as a solution to the buildup. Something like 30+ minute at 3000+ RPMs would burn off the deposits. (I honestly don't know if that works or not.) I would assume Europe's "lean burn mode" would also achieve the same result.
What is interesting is the Audi additive listed indicates it is to prevent "carburetor icing" right on the bottle so I have my doubts that it is any kind of new fancy fuel additive designed specifically for DI motors. I figure almost any good fuel additive will do the same thing.
Honestly this carbon issue sucks for all owners.
Although this is no excuse for a poor design it is the excuse they give and Audi's own software update for this issue modifies valve timing to combat the problem. (But some claim to still have the issue after the software update.)
Audi adamantly denies it has anything to do with oil and some who have used catch cans and such still report the problem.
Also heating the valves to the extreme is listed in the early DI tech documents as a solution to the buildup. Something like 30+ minute at 3000+ RPMs would burn off the deposits. (I honestly don't know if that works or not.) I would assume Europe's "lean burn mode" would also achieve the same result.
What is interesting is the Audi additive listed indicates it is to prevent "carburetor icing" right on the bottle so I have my doubts that it is any kind of new fancy fuel additive designed specifically for DI motors. I figure almost any good fuel additive will do the same thing.
Honestly this carbon issue sucks for all owners.
02-14-2011, 02:59 PM
#14
AudiWorld Member
Audi's argument is that some fuel still reaches the backs of the intake valves during the injection cycle (or even during valve overlap) and the regular amount of additives in the fuel is not enough since, as you pointed out, the valves are not completely washed over with fuel.
Although this is no excuse for a poor design it is the excuse they give and Audi's own software update for this issue modifies valve timing to combat the problem. (But some claim to still have the issue after the software update.)
Audi adamantly denies it has anything to do with oil and some who have used catch cans and such still report the problem.
Also heating the valves to the extreme is listed in the early DI tech documents as a solution to the buildup. Something like 30+ minute at 3000+ RPMs would burn off the deposits. (I honestly don't know if that works or not.) I would assume Europe's "lean burn mode" would also achieve the same result.
What is interesting is the Audi additive listed indicates it is to prevent "carburetor icing" right on the bottle so I have my doubts that it is any kind of new fancy fuel additive designed specifically for DI motors. I figure almost any good fuel additive will do the same thing.
Honestly this carbon issue sucks for all owners.
Although this is no excuse for a poor design it is the excuse they give and Audi's own software update for this issue modifies valve timing to combat the problem. (But some claim to still have the issue after the software update.)
Audi adamantly denies it has anything to do with oil and some who have used catch cans and such still report the problem.
Also heating the valves to the extreme is listed in the early DI tech documents as a solution to the buildup. Something like 30+ minute at 3000+ RPMs would burn off the deposits. (I honestly don't know if that works or not.) I would assume Europe's "lean burn mode" would also achieve the same result.
What is interesting is the Audi additive listed indicates it is to prevent "carburetor icing" right on the bottle so I have my doubts that it is any kind of new fancy fuel additive designed specifically for DI motors. I figure almost any good fuel additive will do the same thing.
Honestly this carbon issue sucks for all owners.
The V10 and V8 has a cyclonic oil separator, but it doesn't appear to do enough to solve the issue.
Toyota has a system on their upper end engines that injects a small amount of fuel into the intake manifold, perhaps new Audi engine designs will incorporate this solution.
Hopefully an enterprising lawyer will bring a class action lawsuit.
02-14-2011, 04:00 PM
#15
AudiWorld Super User
Their claim is it is a maintenance issue akin to brakes, tires, oil changes etc. Weak.
02-17-2011, 07:38 AM
#16
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They can say that all they want, however, I refer to the manual and ask Audi to show me where it lists that as a maintenance item and where it was included in the annual maintenance costs that appear on every vehicle sticker, etc. I have looked and it's not there - they cannot go back and now claim it's maintenance.
02-19-2011, 07:35 AM
#17
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I know many members said the catch-can does not work, but I’m draining about two coffee cups full of liquid every 2500 to 3000 miles. It seems the V10 generates a lot of vapors which fill up the catch-can quickly, looking to upgrade to bigger catch-can at this point. Just happy that most or all of the vapors never make it back into the valves.
02-19-2011, 05:10 PM
#19
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I just got a can of TUNAP micrologic® PREMIUM 133 Valve Cleaner. You spray it into the intake so it should reach the backs of the intake valves.
Haven't had a chance to try it yet, but I will as soon as it's gets a bit warmer.
http://www.tunap.com/en/ranges/autom...ucts/p133.html
I also got 4 cans of the TUNAP micrologic® PREMIUM 173 System Ingredient 'Petrol' which I was told can be used as preventative measure but might also clean some deposits. I tried a can in a full fuel talk a few days ago and the car does seem to be running much smoother.
http://www.tunap.com/en/ranges/autom...ucts/p173.html
Haven't had a chance to try it yet, but I will as soon as it's gets a bit warmer.
http://www.tunap.com/en/ranges/autom...ucts/p133.html
I also got 4 cans of the TUNAP micrologic® PREMIUM 173 System Ingredient 'Petrol' which I was told can be used as preventative measure but might also clean some deposits. I tried a can in a full fuel talk a few days ago and the car does seem to be running much smoother.
http://www.tunap.com/en/ranges/autom...ucts/p173.html
Last edited by cebo0650; 02-19-2011 at 05:23 PM.
02-20-2011, 04:52 PM
#20
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My catch-can is mounted low on the front passenger side, the vapor leave the engine pass thru the catch-can and back into engine. Because the space is very limited the engineering process is tough but possible. I was told for the catch-can to work well it has to be mounted as low as possible to prevent the return liquid coming back into the engine. Inside the catch-can there is a steel-wool like material which helps the liquid stay in the can and at bottom you open a screw to drain. In my opinion, two coffee cups of liquid is a lot, returning to the valves every 2500 to 3000 miles. Since I had this done the car feel like a beast every time you step on the gas compare to before.