I also know a panic coming when I hear it, and the internet is a very, very dramatic place to live...maybe too dramatic
Anyway, Things always make more sense when all the facts come into focus. If we take a poll of Pcar DFi engines, we should be seeing some results and repairs soon. Maybe in a year, we will see big problems...who knows. Until then, we can worry about all of the VW owners problems (most are the little Turbo-DFI cars). If this issue comes to the worst case scenario, as mentioned above, there will be close to 25 million engines failing prematurely in a year or so..(VW+Audi+Porsche+GM since DFI inception)
I have my doubts that it will be as big as that

 

I am assuming you own a 997.2?

There has only been one report that I am aware of that could be considered "engine failure". It is significant power loss, drop in efficiency, coupled with rougher running motors/misfires/CELs.

These issues won't be evident to most owners because it comes on so gradual with buildup. CEL's will send the car to the shop but intake valves are the last place they seem to ever look.

Since you keep hinting that I'm an internet junkie I'll just state that I am an engineer with a mechanical background, and someone that has opportunity to get down and dirty with engine designs. I am not trying to cause panic, but awareness. Owners are getting cheated out of power and longterm reliability.

I am curious how you aquired the figure of 25,000,000 current automobiles with DI engines?

 

Thanks, I have engineering credentials too. Drop the ad hominem stuff OK? Peace!
Anyway, back to the issue at hand!
The number is based on the fact that DFI, GDI engines have been produced since 1998 in toyota engines (no reported catastrophes)
VW group produced 4 million DFI engines last year alone. They have been producing them since 2000. Now it is their mainstay from the 1.4 L on up.
Renault has been using them since 1999 in several of their largest car lines (no major failures)
Mazda is using them since 2006 (all is well)
GM is since 2005 (No reported failures)
BMW is since 2005 (everything else breaks)
I could include every other manufacturer....the number is probably higher than the one I cited.
I don't think folks know how pervasive this tech is!
And it has a long, long track record that should have warned off manufacturers just like the Rotary engine did years back. These companies are not just testing the waters, they are investing comprehensively into this technology.

Just about every manufacturer is using them as mainstay engines.
Investing Billions of dollars into technology that will lead to ruin?
I should also add that VW used a design that is an earlier type of DFI that could be argued is more prone to C buildup. So maybe it is not an indictment of the entire engineering level of the DFI, but rather a design issue that could be ironed out. We have a statistically significant sample of DFI from as early as 1998.
Anyway, as a scientist I am leaving the door open on the matter and will see what happen next!
Thanks for the stimulating conversation

 

can you use Seafoam on DFI engines? that should take care of it.

 

Yes or automatic transmission fluid will do the same job.

 

There is an easy way to end this debate once and for all. I have a 997.2 with 5500 miles. Next oil change I will have the mechanic pull off the valve cover and take a picture of the valves and I will post for all to see. If someone mechanically inclined wants to do this themselves then please do so and let's see with our own eyes.

 

They can save the labor by having them run a boroscope into the intake chamber. If you get pictures, I would love to see. When you get the pictures, please post up your driving habits, climate, and which petrol station you use. Thanks! The visual at 5500 miles may look minimal. I'd really like to see one after break in with, arbitrarily say, 10000 miles? Many are seeing the issues at around 10k and forward.

If you have a considerable build-up, it will only softed a small top layer of it. It won't actually clean it off. Pulling the manifold off and soaking the valves overnight with seafoam DID soften it up even more but it still took about 45 minutes to clean each valve. So running it through the system and letting it sit for 5-10 minutes won't put a dent in it. I bet that if you start with a clean engine(or get the intake valves cleaned) and then apply this treatment often that it will keep the buildup away. That is merely a theory of mine. I do not know of anyone who has done exactly that and then documented the results yet.


I am only trying to help out. John is trying too hard to be condescending for me to share this further in this thread. He certainly knows much more about this than I ever will and only sees my explaining my background as a quasi-threat which must be mocked and belittled.

To the rest I wish the best.

 

ragdoll,
I believe you may have been referring to this thread which has the picture you presented of the carbon build up on intake valves. They do not seem to be as concerned about the relatively small loss of power form this build up.
-------

Firstly I'm quite sure they only took the pictures to cover them selves. If Audi UK have said its OK, then the Audi center can only follow those instructions, Audi UK dont reconsider.

If your valves look like this, it is normal.

(Pics Posted by andyuk911)
http://i140.photobucket.com/albums/r34/saaber1/val...
Thats from a 2.0TFSI with 20k on the clock. .

http://i390.photobucket.com/albums/oo344/rAudiguy/...
Thats a 4.2FSI at 19k

Its quite likely the technician has never seen this before as we dont take alot of RS4 manifolds off, we dont even see alot of petrol engines to be honest. I know I've never had an RS4 manifold off, But I have had a few off of 2.0FSI and TFSI engines, (purely to replace failed injectors) and they all look like this.

It because of the FSI direct injection, normally the fuel injector is above the inlet valve so the fuel actually cleans the valve as the engine runs, with FSI the fuel is injected inside the camber so the fuel never touches the valve. All manufacturers are now slowly moving over to direct fuel injection, its the only way to get through the emissions regulations and improve fuel ecconomy. Although personally I think its a stupid idea, but then I dont care to much for how much CO2 my car produces, the worlds motor manufactures have to care about that. All car's since like 1980 odd have the crack case fumes (oily vapor) fed back into the inlet manifold, it is the residue of this that leaves sticky oil on the valves which then attracts carbon from the crank case fumes or EGR. We have FSI engines over 120,000 miles showing no side effects of this carbon build up. If anything you would expect to see sticking valves, Jag straight six engine used to do this, so I know exactly what it feels and sounds like, and I havent seen it yet on Audi's.

If the build up on the valves wasnt there, the volumetric efficiency of the engine (air flow) would be improved and you would gain a little power, BUT That build up on the valves will not cost you 100bhp no matter what. I recon if you removed the heads and spent a day decoking the hole thing you would gain 10-15bhp max.

Given how smooth the power graph is, even though its down on torque, my best educated guess is either the manifold flap fault is preventing it from making toque at higher rpm (which is what variable length manifolds are for after all) OR as soon as the ECU sees any engine fault code it goes to a default map and runs at reduced performance.

You will have to wait and see how it performs after they replace the faulty manifold and or flaps.

The oil consumption test will prove if the engine is any good, in terms or bore/piston ring wear. If the car passes you can feel confident its a good mechanical engine, and the fault will be something electrical or ancillary. If your car fails the oil consumption test, basically using more than 1 lire of oil in 1000km/600miles, (but checked vary accurately by weight, but rule out expansion for heat etc) then Audi Uk will likely authorise a new one to be fitted. I did one is an V8 S4 last year for that very reason.

 

Is it a joke to call _this_ 'normal' ? From what I know about engines it is not nearly normal.
Seems like in Audi`s mind only not-normal situation is that final when carbon build-up will finally make valve rod to bend or else.

 

It sounds to like the auto companies are in bind in that they feel the only way they can meet the new exhaust standards is through DFI. From a traditional design perspective I would not like to thing of the carbon build up as normal but for the near future ( until they figure it out) they ( we) might have to live with it. My question is how much of a problem is it? Does the carbon build up to a certain point only and stabilize or does it continuously get worse? If it is the former it might be something that will never be noticed by 90% of drivers. If the latter, it would be a real problem and the new "tune up" procedure ( cleaning it out) for the DFI cars.

 

Problem is very simple indeed - valve goes back and forth at 7000 RPM, carbon build up shifts center of gravity away from where it should be so valve begins to vibrate much harder, beats up its header tunnel then finally breaks off.

Really engines that are engineered to run a lot of hours at 6+ RPM usually use different considerations than engines that routinely run at 2-3K RPMs. So , well, if anybody will actually take a picture of DFI Porsche engine with some milage on it - it would be very interesting to see.

 

I am looking into purchasing a 05 997S. I read that since 997 engine was a close evolution of the 996, they have been quite refined and no significant changes between 2005-2008. I read that it is possible to have RMS/IMS leak in 997S of any model year. Are there specific mechanical problems that plaque 05 997S only?

Thanks,
Jim