ADias

Is anyone w/ a DFI engine experiencing valve carbon buildup? as reported HERE.

Picture example:



This may be caused by people who continuously run short trips, never temp cycling the engine properly. Your thoughts?


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richc

How many miles created that?

OCNYPORSCHE

So that is where all the oil goes. My 2008 CS (DFI) uses more oil than my 2005 CTT (non-DFI) Does anyone think that those total fuel system cleaners will help this?

porsche52

The total fuel system cleaners do work (BG,etc). But you are not thinking about what you are saying. This is a DFI engine, Direct meaning below the intake valves, Directly into the combustion chamber!! Now that were are clear about that, I have seen several DFI Cayenne intake valves look just like this one, very low miles too, less than 5k. I personally think the build up is due to the lack of fuel injection on top of the valve, as in the MPI engines to allow products like BG control deposits on the valves. I also noticed that the build up was more on the middle cylinders 2-3 and 6-7. This is were the majority of the crankcase gases vent, hummmm? All oil mist and air, no fuel to help aid cleaning, thats the problem IMO

OCNYPORSCHE

Ok I see what you are saying. So in your opinion, why does it appear that DFI engines burn a good amount of oil, and possibly more than MPI?

porsche52

How much oil is the 08 CS using? Have you started a consumption test? What oil are you using? I have not noticed a wide spread oil consumption issue on the 2nd gen CS, now the 05 CTT is a different animal. I bet if you pulled your bank 2 boost hose (drivers side, from turbo to intercooler) you will drain out about a 1/4 quart of oil. They all do this, back in 04 pepole were replacing the bank 2 turbo because they thought it was the source of the oil(porsche was not happy) then they started to replace the air/oil seprator (bank 2 valve cover) once again porsche was not happy. Finaly porsche relased a TSB titled " repair instruction in the event of oil leak at turbocharger" in which we were told to install a new o-ring and or boost hose to prevent the oil from hitting the ground, nevermind why that much oil is in the intake track! The crankcase is vented through that side of the intake under boost, (low pressure @ inlet of turbo). Just the way it is I guess, as long as it does not effect engine performance Porsche will probably turn there cheek.

A intersting thought, the new service interval is now every 12k for the 2nd gen 9PA's. LOF @12k, Minor (major turbo) service @ 24k (plugs on Turbo!!) , Major @ 36K (plugs on S). Pretty pricy little pig to feed.

OCNYPORSCHE

I am using Mobil 1 0W40 in both my Cayennes. My 2005 CTT is using about 1 qt per 2K, and the 2008 CS is using 1.5 qt per 2K. Not as bad as others and I suppose well within Porsche spec for normal.

leek

I am using a quart every 4500-5000 miles in CTT 08

Cpa4S

posted by a US lawyer i bet!

Vino

porsche52,
So what is the remedy from Porsche on the DFI issue?

I have seen this issue wide spread from VW, AUDI and BMW.

Following the VW side looks as if some people are developing or developed a catch can system and are messing with the PCV system to control blowby and so on to reduce the issue.

Out of all the motors the RS4 V8 seems to have the most issues with the build up, even the oil in the DFI cars seem to be toasted by 3k or 5k from the heavy dilution of fuel.

Keep us updated.

porsche52

Will do

JHoffman

Hey sorry to kick a dead horse. I took these pictures and somehow they pollinated all over the interweb. Any questions I will try to visit here a little more.

ADias

What kind of driving caused this? short driving mostly?

What have you done about this? Did the dealer recommend an engine cleaning exercise such as Techron, or GM TOP Engine cleaner or Seafoam?

Thanks.

JHoffman

I did the work. It was a cayenne turbo w/ 25k on it. It is driven hard. Not sure about distance but where the owner lives nothing is "short". This vehicle had no problems resulting from the carbon on every valve. Performance, idle and cruise actual values were all normal. If he does come back for this concern I would like to try walnut media blasting and a cleaner during services. None of this is up to me.

INURGRL951

So it looks like the 2nd gen cayenne has there own share of problems. But wait I got an 04 Turbo and a 06 Turbo S and either one does not use a drop of oil I use castrol full sytec and change my oil every 4k-4.5k because I noticed the oil consumption start around 6k mile on the oil so why add a fresh quart to old oil just change it at an earlier mileage. I remamber when Porsche had the oil change intervals at 20k!!!!! That's where I think one mistake is even 12k now is way to long especially on a turbo cayenne.