3.0 Liter carbon buildup?
02-09-2016, 07:21 AM
#21
AudiWorld Senior Member
Owners that have installed catch cans in the hope that it would stem carbon deposits have been disappointed at the results. Carbon build-up is still an issue.
02-09-2016, 07:58 AM
#22
AudiWorld Member
I believe the buildup is from oil that gets picked up by blow-by gases flowing through the crankcase and then back to the intake via the PCV system.
The 'Italian tune-up' may even make things worse by causing more blow-by gases from hard driving, as well as sucking them into the intake with the vacuum created when you close the throttle at high rpm.
The 'Italian tune-up' may even make things worse by causing more blow-by gases from hard driving, as well as sucking them into the intake with the vacuum created when you close the throttle at high rpm.
02-09-2016, 08:02 AM
#23
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02-09-2016, 08:19 AM
#24
AudiWorld Expert
http://www.edmunds.com/autoobserver-archive/2011/06/direct-injection-fouls-some-early-adopters.html
02-09-2016, 09:09 AM
#25
AudiWorld Member
You will always get some byproduct in there. With port injection it was never an issue, because the valves were constantly being washed by the fuel. This is an old article and manufacturers have made some improvements since then, but it gives you some basic background info on the issue:
Direct Injection Fouls Some Early Adopters - AutoObserver
Direct Injection Fouls Some Early Adopters - AutoObserver
This is what I was referring to:
Tony Chick, principal engineer at European Performance Labs in Stratford, Connecticut, has made a career of repairing and rebuilding high-performance engines from Audi, Porsche AG and BMW, among others and his operation has garnered a reputation among car enthusiasts as a go-to place for cleaning DI engines that have become choked with carbon. Chick thinks the problem for most affected engines can be traced to the breathing system – specifically, the design of its crankcase ventilation and exhaust-gas recirculation components.
02-09-2016, 09:14 AM
#26
It's not all blowby either, it's actual crank venting. It's also potentially from the valve seals themselves. then you add in EGR, and no way to clean the valves, and you get buildup.
02-09-2016, 10:42 AM
#27
AudiWorld Member
Valve seals and blow-by seem like a bit of a cop-out since, according to the article, other manufacturers do not have this issue. Crank venting and EGR makes sense, and again, design issue.
02-09-2016, 10:46 AM
#28
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Also, since your car is a 2016, it has the latest version of all the related systems, so you really shouldn't have to worry about this.
02-09-2016, 12:12 PM
#29
AudiWorld Super User
The VW FSI patent is a highly technical read, but worth it to many Audi enthusiasts. Extra credit will be awarded for reading it 
The patent lists carbon buildup from 3 possible sources: Valve timing overlap (internal EGR), seeping valve oil seals, and crankcase ventilation vapors. It lists a half dozen or so systems to deal with the carbon buildup problem such as special valve seals, oil additives, specific running temperatures, valve coatings, etc., etc. Internal EGR is a tough one because valve overlap is ground into camshafts for performance reasons, and not too many of us are willing to give up any performance.
Personally, I wouldn't be concerned about carbon buildup on a 3.0T.
Click below for link to patent:
Patent US6866031 - Direct injection internal combustion engine - Google Patents
The patent lists carbon buildup from 3 possible sources: Valve timing overlap (internal EGR), seeping valve oil seals, and crankcase ventilation vapors. It lists a half dozen or so systems to deal with the carbon buildup problem such as special valve seals, oil additives, specific running temperatures, valve coatings, etc., etc. Internal EGR is a tough one because valve overlap is ground into camshafts for performance reasons, and not too many of us are willing to give up any performance.Personally, I wouldn't be concerned about carbon buildup on a 3.0T.
Click below for link to patent:
Patent US6866031 - Direct injection internal combustion engine - Google Patents
02-09-2016, 12:48 PM
#30
It might seem like a cop out to you, but it's the cause. The "design flaw" is that unlike with port injection, with FSI there is no gas going past the valves, EVER. So there is nothing to clean them off. The only way to prevent this would be to either have a fuel injector spray in the intake manifold, or, route EGR and PCV directly into the combustion chamber.