GDI Tech

Sounds good! Anyone needing more, just ask.

Superfly_A6

GDI Tech.

First, thank you for all your posts. Very informative and yes, not everyone gets to see this everyday. I personally didn't even know about the valve problem until I read this.

Now, what do you think will happen going forward? It seems like the industry is stuck on GDI because of the emission regulations. I'm not going to reach that far as to suggest that this is some kind of a bigger plot/scheme, but really, what is going to happen moving forward? Is there a solution on the horizon to fix valve coking, or move away from GDI altogether? Or are the consumers going to be hit with higher bills to fix these issues and/or any other issues arising from GDI design.

Thanks again,
Diesel rules

Acuransx

Last word from me on this which is on a positive note. A client took me to lunch today. She drives a 2012 A6 3.0T -- 65,000 miles. Other than the couple of recalls, an expensive brake job and an upcoming battery replacement she has had no issues. No check engine lights or drivability issues. We didn't drive very far but her car rode and sounded exactly like my /15 that has 50K less miles than her car.


Best,
Jeff

GDI Tech

The industry has been forced to adopt GDI (different automakers use different acumen for the same thing, but DI, or GDI is the industry reference) to meet ever increasing CAFE fuel economy standards and stricter emissions regulations, so no, it is here to stay. That is why so much effort and money is poured into this to help reduce the effects, and just looking back 8-10 years we see great improvements as far as rate and severity of the coking issue, but the methods being used are what are as big of concerns.

If we look back at the history of the PCV system, prior to the mid 1960's no vehicles ran them other than the original GM design from WWII to deal with crankcase vapor explosions in Tanks and other vehicles where a "road draft" vent was not sufficient. The US mandated the PCV system as we know it today in the mid 1960's, and it was purely to reduce ground water pollution from the run-off of millions of vehicles dripping oil out of the road draft vent tubes onto the roadways. Back then, most engines lasted app. 40-50k miles before needing a total rebuild due to wear. Now not taking oils/filters/materials used, etc. that extend engine life, these same engines, running the same oils with the same oil change intervals (from 1500 miles to 2500 miles was standard back then) these same engines running the same oils, were now lasting 2-3 times as long as wear greatly reduces. It was not until studying this that engineers found most engine wear was caused by combustion by-products and other contaminates entering the crankcase, mostly as blow-by. The PCV system was now removing most of them before they settled into the oil and were still in a gaseous state. So engine oil stayed cleaner and contaminate free far longer, thus less wear. Now the automakers main focus is on internal air/oil separation as oil mist is the main culprit causing the coking. BUT and this is a big BUT, when they separate and retain this oil mist internally, it is also retaining most of the contaminates that used to be removed from the crankcase allowing the engine oil to be able to contain and still protect. Combine that with raw fuel, the next biggest contaminate that GDI engines experience far more of due to the intense pressures (fuel injectors deliver at 2,000-3,000 PSI now vs the 45-50 PSI of port injection) and higher compression ratios so this overwhelms the engine oils ability to protect as well. The result is wear is greatly increased. It seems only the "super cars" are doing it correctly with external separation, but the average consumer would never accept having to service an external separator as most drive and put fuel in and nothing else to maintain there new vehicle unless a DIC message prompts them to visit the dealer.

Most are not aware just how close to budget a vehicle has to be and even a .50 cent addition much of the time is nixed even if it was a dramatic improvement. We cannot forget these are mass produced, and the target demographic each model is targeted towards is studied extensively. So let's take GM for instance (where I came from). Recently they paid over a $billion in settlement's and it is not over for a simple ignition switch design flaw that was identified by engineers app 10 years earlier, and a fix was presented for less than .50 cents per vehicle. It was decided to not spend that extra .50 cents and let it take it's course, and the results were well publicized. Who got blamed? The lower level engineers that first found it and brought it to management with a fix. That is one of hundreds of examples as every automaker has had similar recalls, etc. through the years. So it is rarely what is "best" in the process, it is what is "best" within strict budget parameters and what can get by without widespread discovery. VW/Audi and it's software emissions debacle on the TDI engines (which they are and were all still extremely clean burning and was hardly a "scandal" IMHO. Just a way for the Feds to collect huge fines from them).

The variable valve timing and fueling events have had little actual improvement. Adding in the small port injectors is far too little fuel contacting to reduce severity, but created another issue of increased knock retard. So the industry has really the past few years concentrated on the internal air/oil separation and accept the reduced life of the engine. And as Acuransx just gave a perfect example of, most will never realize an issue until past the average ownership period of app. 3 years. Until CEL's come up for random misfires, all of the degradation is gradual in nature as the frog in a water pot. Put a frog in boiling water and he jumps right out. Put him in warm water and bring to a boil and he will stay in the pot and boil to death.

We rarely can notice any change when it is gradual. So that is the reason all of the studies of before and after dynomometer measuring to to document. Buy the time misfires and other obvious symptoms crop up, the damage is done to an extent.

Hope that helps!

plat27265

GDI Tech, I have been following this thread since its inception and, I have to say, you are one patient engineer. As I read through your posts, you tirelessly explain the coking issues in GDI engines like a university prof never tiring of teaching the same lesson each year. I admire your dedication and knowledge in this matter. After reading the thread up to this point, I have a good basic understanding of various things that cause the coking issue in GDI engines plus the harmful particles that affect the longevity of GDI engines. This is a very good thread and I have recommended them to other people in other Audi and VW forums that are engaged in a conversation about valve coking.

Sorry for this diversion but I just can't help react to your opinion on this TDI scandal. I feel the same way as you on this TDI software emissions debacle. Technically, yes, VW/Audi lied about their TDI clean diesel campaign through this cheat software. However, I don't think they deserve this extreme reaction from the feds and TDI Owners. When people from North America go out to buy a diesel car, they want it because it uses much less fuel compared to their gasoline-burning cousins. I know a lot of friends and family that own TDI cars but they don't brag about low CO2 emissions. They do brag about how they can go for 900 kms on a single tank or what is good for their pocket. In Europe, I understand how TDI owners will feel duped since every new car sold comes with information about how much CO2 they emit and how much tax you pay for those emissions. In North America, those CO2 rating don't even get mentioned or published. I agree that this fiasco is hardly a 'scandal' of earth-shaking proportions especially here in North America where diesels are not as popular compared to Europe.

Swes

From what I understand diesels do also suffer from carbon build up however since they do not have a throttle plate and consequently don't build nearly as much vaccum in the runner area they are less susceptible.

My best advice for mitigation havig dealt with it on various cars including non GDI vehicles is :

Don't overfill the oil ie NICHTE UBERFULLEN! Written on top of every Audi oil cap. Max is max does not mean recommended oil level . I strongly encourage people to fill just enough and leave it such that the oil level is just on the stick .

Dont idle excessively as it increases the vaccum, raises oil temps and decreases flow over the valves.

Change your oil as reccomended or more . This prevents deterioration from affecting the oil .

Use the proper oil or 504/507 oil . These oils offer extreme protection with low contaminate and volatility and are required for diesel VW Audi vehicles .

Don't baby the car. Build up will loosen and fall off with high RPM and flow . It won't fix totally built up engines but it does help.

did I mention make absolute certain you don't over full the oil? 4.5 -5.5 quarts doesn't affect lubrication but if the car was meant for 5 it certainly will affect PCV performance.

GDI Tech

Thanks for the kind words. I do some training on the side for instructors at Automotive Tech schools on the subject as they cannot find any where to get accurate information and the next generation of techs really should understand all of this as they will be the ones dealing with it. Factory is NOT providing them any but the bare minimum as they are working so hard to keep this "underwraps" so to speak.

I am 100% with you on the outcome of the diesel debacle. I have run diesels since the 1970's (240D Mercedes) and then of course the early VW pick up truck and the fuel economy was always the main benefit.

Excellent contribution! Yes, the overfilling of oil is something I had not mentioned and definitely would contribute.

trlman

For those who may have some interest. A video by GDI Tech, on a Q7 install.

DanfZX14

It looks pretty straightforward which becons the question why don't the manufacturers just incorporate this into the original vehicle design?

snagitseven

I was thinking the same thing. Couldn't have added much cost.