Valve coking and direct injection engines
11-22-2016, 01:52 PM
#1
Audiworld Junior Member
Thread Starter
Valve coking and direct injection engines
After doing some research on the horrible effects of Direct Injection on the up stream side of the intake valves, I decided to modify the PCV system on my 2012 A6 3.0. I looked at a lot of you tube films regarding the use of catch cans, and only one outfit truly impressed me. Tracy Lewis of RX products has the answer to this problem.
When I contacted him about a system for both my Audi and my JCW Mini Cooper, I was told he had done many Mini's but had yet to have an A6 in the shop. I then scheduled an appointment to bring the A6 to him and fabricate a system.
The installation is quite simple, the two hoses off the back of the valve covers which are connected to the bottom of the manifold, are disconnected. A tap is placed into the air intake, after the air filter, and this is connected to the passenger side valve cover. A plug is the put into the hose removed from that side.
On the drivers side, a hose is run from the valve cover to a baffled, "American Made" catch can, and the hose that came of the valve cover supplies the necessary vacuum.
Since this was installed on a car with under 10K miles, I did not take the supercharger off to check the amount of build-up presently on the valves.
I checked the drain on the catch can this AM, after driving only about 100 miles, I can report that there was a bit of oil in the can. I think this is the answer to the problem. I will check the can again after about 500 miles, to get a better idea of how often this will have to drained.
RX Products now has all the info necessary to sell simple DIY kits for these cars. If you want more info, contact Tracy Lewis (rxproducts@aol.com)(727)422-0076
When I contacted him about a system for both my Audi and my JCW Mini Cooper, I was told he had done many Mini's but had yet to have an A6 in the shop. I then scheduled an appointment to bring the A6 to him and fabricate a system.
The installation is quite simple, the two hoses off the back of the valve covers which are connected to the bottom of the manifold, are disconnected. A tap is placed into the air intake, after the air filter, and this is connected to the passenger side valve cover. A plug is the put into the hose removed from that side.
On the drivers side, a hose is run from the valve cover to a baffled, "American Made" catch can, and the hose that came of the valve cover supplies the necessary vacuum.
Since this was installed on a car with under 10K miles, I did not take the supercharger off to check the amount of build-up presently on the valves.
I checked the drain on the catch can this AM, after driving only about 100 miles, I can report that there was a bit of oil in the can. I think this is the answer to the problem. I will check the can again after about 500 miles, to get a better idea of how often this will have to drained.
RX Products now has all the info necessary to sell simple DIY kits for these cars. If you want more info, contact Tracy Lewis (rxproducts@aol.com)(727)422-0076
12-01-2016, 08:14 AM
#2
As in all GDI engines we have no fuel washing the intake valves, so they run far hotter and bake on the contaminates and oil mist to the back sides of the intake valves. This also is now a hard carbon deposit very abrasive and damaging compared to the soft carbon pf past port injection engines.
Since GDI the fuel is introduced directly into the combustion chamber, and not until milliseconds before spark ignition, the pressures involved are in the 2,000-3,000 PSI range and this results in many times the raw fuel being forced past the rings and diluting and contaminating the engine oil causing premature wear. Especially timing chains. The system described provides full time evacuation and air/oil and other contaminate separation. You also want to ONLY run a full synthetic oil as the syn blends leave far more deposits and residue after burning on than full syn. Top tier fuels while do nothing to keep the engine clean internally, but do help keep the injectors spray pattern true and correct as at these pressures, even a small disruption results in droplets reforming and incomplete combustion.
Oil changes. Most GDI engines the oil is at it's maxim ability to deal with acids (TBN), reduced viscosity from fuel dilution, and over loaded with the greater amount of abrasive particulate matter GDI engines experience, so no longer than 5k miles between changes, and finally, if new, break that engine in right so the rings seat properly, and that involves hard running in the first 100 miles to load the rings both during acceleration and engine braking deceleration. I prefer from a roll in second gear, full throttle to 5k RPM's and allow the engine to brake back down. Repeat 4-5 times and then get that factory fill oil full of assy debris and wear in filings drained out.
These are not the engines of old and GM recently lowered engine warranty period on all GDI engines from 100k miles, to 60k miles, and now 3k miles. Ford is also at 3k miles and most euro and eastern made as well are following.
The system Mitch describes is the most effective and robust on the market, but beware of the cheap made in China glued together counterfeits being sold with the same brand on them. (McNally, rxspeedworks, etc. are the counterfeiters).
Tons of catchans on the market, many from big brands, but most only trap from 15-30% of the compounds you want to stop, and these are 95% effective. Now, there is no way to stop all of the deposits over time as most GDI engines use variable valve timing events to emulate EGR system functions allowing some back filling of burnt gasses back into the intake port and this makes contact with the back sides of the valves as well, but should prevent 90% plus of them.
Want more technically explanations and details on todays GDI engines and how to care for them? Just ask.
:cheers:
Since GDI the fuel is introduced directly into the combustion chamber, and not until milliseconds before spark ignition, the pressures involved are in the 2,000-3,000 PSI range and this results in many times the raw fuel being forced past the rings and diluting and contaminating the engine oil causing premature wear. Especially timing chains. The system described provides full time evacuation and air/oil and other contaminate separation. You also want to ONLY run a full synthetic oil as the syn blends leave far more deposits and residue after burning on than full syn. Top tier fuels while do nothing to keep the engine clean internally, but do help keep the injectors spray pattern true and correct as at these pressures, even a small disruption results in droplets reforming and incomplete combustion.
Oil changes. Most GDI engines the oil is at it's maxim ability to deal with acids (TBN), reduced viscosity from fuel dilution, and over loaded with the greater amount of abrasive particulate matter GDI engines experience, so no longer than 5k miles between changes, and finally, if new, break that engine in right so the rings seat properly, and that involves hard running in the first 100 miles to load the rings both during acceleration and engine braking deceleration. I prefer from a roll in second gear, full throttle to 5k RPM's and allow the engine to brake back down. Repeat 4-5 times and then get that factory fill oil full of assy debris and wear in filings drained out.
These are not the engines of old and GM recently lowered engine warranty period on all GDI engines from 100k miles, to 60k miles, and now 3k miles. Ford is also at 3k miles and most euro and eastern made as well are following.
The system Mitch describes is the most effective and robust on the market, but beware of the cheap made in China glued together counterfeits being sold with the same brand on them. (McNally, rxspeedworks, etc. are the counterfeiters).
Tons of catchans on the market, many from big brands, but most only trap from 15-30% of the compounds you want to stop, and these are 95% effective. Now, there is no way to stop all of the deposits over time as most GDI engines use variable valve timing events to emulate EGR system functions allowing some back filling of burnt gasses back into the intake port and this makes contact with the back sides of the valves as well, but should prevent 90% plus of them.
Want more technically explanations and details on todays GDI engines and how to care for them? Just ask.
:cheers:
12-01-2016, 08:38 AM
#3
AudiWorld Super User
After doing some research on the horrible effects of Direct Injection on the up stream side of the intake valves, I decided to modify the PCV system on my 2012 A6 3.0.
Since this was installed on a car with under 10K miles, I did not take the supercharger off to check the amount of build-up presently on the valves.
RX Products now has all the info necessary to sell simple DIY kits for these cars. If you want more info, contact Tracy Lewis (rxproducts@aol.com)(727)422-0076
Since this was installed on a car with under 10K miles, I did not take the supercharger off to check the amount of build-up presently on the valves.
RX Products now has all the info necessary to sell simple DIY kits for these cars. If you want more info, contact Tracy Lewis (rxproducts@aol.com)(727)422-0076
12-01-2016, 12:01 PM
#4
Audiworld Junior Member
Thread Starter
Yes, car has only 9500 miles, just purchased with 8700 miles. Had no idea of the consequences of GDI until I started reading posts on the Mini Cooper websites. Upon removing the intake and inspecting the valves on the Mini (60K miles) I was astonished to find the amount of build up on the valve stems. Yes, I am worried, as I don't relish the idea of having to media blast the valve stems on the Audi.
12-01-2016, 12:46 PM
#5
AudiWorld Super User
I haven't seen many threads about build-up on the valves. Plenty about the Bose system, uncomfortable seats and the high price of brakes and oil changes.
Is this the 2012 A6 with the left front headlight adjusting problem?
Is this the 2012 A6 with the left front headlight adjusting problem?
12-01-2016, 12:56 PM
#6
Audiworld Junior Member
Thread Starter
Yup, found the problem. Adjuster screw for vert adjustment, dislodged from socket. Cut a hole in top of lamp above adjuster to pry adj. screw back into socket.
12-01-2016, 12:58 PM
#7
AudiWorld Senior Member
I am a frequent and regular visitors in various Audi and VW forums for years. I have never heard or read about carbon build-up issues with the 3.0L TFSI motor. This is one reason why I ditched my 2011 VW GTI with the EA888 engine and moved on to my current S5. The EA888 engine is a turbo 4 and it will fall prey to carbon build-up issues over the long run. Lots of Owners have confirmed it. I think you may have over-reacted on this matter. However, I don't blame you for getting scared of carbon build-up issues on your A6 due to your experiences with your JCW Mini Cooper. Both are DI engines but supercharged engines seem to less susceptible to carbon deposit issues behind the intake valves compared their turbo-charged brethren.
Trending Topics
12-01-2016, 01:32 PM
#8
Audiworld Junior Member
Thread Starter
I don't see where there world be any less valve coking on a supercharged engine vs a turbo. You still have no fuel passing past the valve stems to provide a cleansing action, while the PCV system is still dumping oil and condensation into the intake. The addition of boost will also accentuate the problem as there is always some blow by, thus dumping more oil on the hot valve stems to accumulate.
12-01-2016, 04:18 PM
#9
AudiWorld Super User
Any engine is susceptible to build up of valve stem deposits. Other than one or two instances, I have not seen any widespread complaints of premature coking on the 3.0T TFSI engine. The engine has been around long enough in several models that if there was a wide spread issue, we would have heard about it. The best prevention is to use premium Top Tier fuel.
There is a known issue with the secondary air ports on some 2012/2013 3.0 TFSI engines where deposits can form due to the design of their location. For those cars, Audi has provided a 10 year/120K extended warranty that will cover carbon build up cleaning of the SAIs if a CEL is thrown. Valve cleaning is not covered under this warranty but again, I don't see any evidence in the forums of widespread issues here.
There is a known issue with the secondary air ports on some 2012/2013 3.0 TFSI engines where deposits can form due to the design of their location. For those cars, Audi has provided a 10 year/120K extended warranty that will cover carbon build up cleaning of the SAIs if a CEL is thrown. Valve cleaning is not covered under this warranty but again, I don't see any evidence in the forums of widespread issues here.
12-01-2016, 04:26 PM
#10
AudiWorld Member
I wouldn't lose a wink of sleep over it.
Run BG MOA oil additive in the oil.
Adding water/meth injection would be even better - then you can turn up the boost and timing as well. I've never seen a cleaner engine than one running water injection.
Run BG MOA oil additive in the oil.
Adding water/meth injection would be even better - then you can turn up the boost and timing as well. I've never seen a cleaner engine than one running water injection.