DFI engine issues?

[ADias]

Take a look at this THREAD discussing severe gunk buildup on Cayenne DFI engine's valves.

Will 997.2's 9A1 engines develop this?

[wvicary]

Is that an intake valve? Many things can cause deposits including using poor quality oil and driving styles. Any idea how many miles on this engine??

[PTEC]

I guess for as nasty as it looks whats really the issue here? It seems that with the fuel being directly injected to the cylinders, there should be no issues with the carbon sucking up fuel from the air fuel mixture as it goes into the intake causing driveability problems. What kind of problems do the higher mileage audi DFI engines run into?

[vizcarra44]

I guess for as nasty as it looks whats really the issue here? It seems that with the fuel being directly injected to the cylinders, there should be no issues with the carbon sucking up fuel from the air fuel mixture as it goes into the intake causing driveability problems. What kind of problems do the higher mileage audi DFI engines run into?

This carbon buildup is a problem with any DFI engine, the Air flow is getting distrubed as it goes by the valves, the DFI engine needs the air to come in at a certain angle and is important during stratified injection. I just saw today an audi with same problem, the audi guys are keeping busy with this issue. I have also seen this on very low mileage cayenne's as well. The valves are like heat sinks when the engine is turned off, the oil fumes in the intake are collecting on the valves.

The only solution is preventive maintenance, there is a service that inducts a strong mist of induction cleaner at idle that will help keep the valves clean and the intake. Looks like when these cars go out of warranty, there are going to be some high repair bills if this preventive maint is not done. Just an opinion from a Porsche Miester Tech. :unsure:

[pedsurg]

I guess for as nasty as it looks whats really the issue here? It seems that with the fuel being directly injected to the cylinders, there should be no issues with the carbon sucking up fuel from the air fuel mixture as it goes into the intake causing driveability problems. What kind of problems do the higher mileage audi DFI engines run into?

This carbon buildup is a problem with any DFI engine, the Air flow is getting distrubed as it goes by the valves, the DFI engine needs the air to come in at a certain angle and is important during stratified injection. I just saw today an audi with same problem, the audi guys are keeping busy with this issue. I have also seen this on very low mileage cayenne's as well. The valves are like heat sinks when the engine is turned off, the oil fumes in the intake are collecting on the valves.

The only solution is preventive maintenance, there is a service that inducts a strong mist of induction cleaner at idle that will help keep the valves clean and the intake. Looks like when these cars go out of warranty, there are going to be some high repair bills if this preventive maint is not done. Just an opinion from a Porsche Miester Tech. :unsure:

Vizcarra44: Thanks

Could you elaborate on this service ?? Is it a reg Porsche dfi program or a generic inductor cleaning, or neither ??

What should we dfi owners be doing to prevent this ??

Thanks again

Jack Tampa

[wwest]

Take a look at this THREAD discussing severe gunk buildup on Cayenne DFI engine's valves.

Will 997.2's 9A1 engines develop this?

I don't think I can "buy" into this, seems more like a scare story to me.

With DFI there is ONLY air on the intake side of the valve, if the picture was actually from a DFI engine then the valve seals would have had to fail, or the valve/seat is leaking pretty seriously.

What is the source of the picture...??

[ADias]

The source of the picture is a Cayenne DFI engine. On the intake tract there is air and EGR products. The latter is what we see in that picture.

I first posted this thread asking a question re the 997.2 DFI engine and this issue. I do not think that this is a major issue - I have since bought a 997.2S...

[wwest]

The source of the picture is a Cayenne DFI engine. On the intake tract there is air and EGR products. The latter is what we see in that picture.

I first posted this thread asking a question re the 997.2 DFI engine and this issue. I do not think that this is a major issue - I have since bought a 997.2S...

Sorry, I'm still not buying in.

I have disassembled and cleaned not just a few EGR recirculation valve systems over the years, mostly Lexus', and I've never seen crud of that nature. Think of what the catalytic converter would look like if the exhaust gasses contained "deposits" of that type/volume.

Oh, how many miles on that Cayenne...??

[wvicary]

In the link it states that the pics came from a Cayenne with 2X,XXX miles but was operating fine. The pics do look bad but is the build up really causing a problem? I have seen VW TDI engines with EGR's and intake blocked 80% due to build up from using the incorrect engine oil and maybe this is the case here. I think there is more to this story and I'll wait for more data to get the measure of things.

[ADias]

The source of the picture is a Cayenne DFI engine. On the intake tract there is air and EGR products. The latter is what we see in that picture.

I first posted this thread asking a question re the 997.2 DFI engine and this issue. I do not think that this is a major issue - I have since bought a 997.2S...

Sorry, I'm still not buying in. ...

What are you not 'buying in'? The problem or a new 997.2? :)

[wwest]

In the link it states that the pics came from a Cayenne with 2X,XXX miles but was operating fine. The pics do look bad but is the build up really causing a problem? I have seen VW TDI engines with EGR's and intake blocked 80% due to build up from using the incorrect engine oil and maybe this is the case here. I think there is more to this story and I'll wait for more data to get the measure of things.

"...more data to get the measure of things..."

EXACTLY...!!

[johnm]

from a scientific standpoint, I think we first have to consider the fact there are well documented case of carbon buildup in non-dfi engines as well. There are pictures of this type of issue that predates the widespread usage of DFI in non diesel engines. So, we have fact #1, and that is that non-DFIs have this issue as well.

Another issue: Most of the horror pictures are taken of VW/audi products such as the VW sourced Cayenne or the ubiquitous 1.8/2.0 DFI-turbo motors. I believe that a few plausible theories are floating around now concerning the EGR valve and the angle of the injectors. If they were all this bad, why would VW continue to produce the design. The liability would be too great, would it not?

I am also not convinced that the technology itself is faulty, but rather the application of such technology in certain vehicles or circumstances. We are seeing the vast majority of new vehicles move to this technology, which was mass produced since 1998 in the japanese market, and then went on to become the entire european market in recent times. The companies that are investing in this technology would have noted these doomsday issues long ago and would probably avoided the systems, in the way that Rotary engines became curiosities in the 70's, but eventually fell from the face of the earth. (sorry mazda RX-8!!) So we have 20-30 million of these systems on the road today and scarcely a new car can be found without the tech. Engineers are just not that silly to ignore such problems if they were inherent and unavoidable by design. We have also not seen the massive number of vehicular failures that this theoretically flawed technology should in fact be producing! More so, we just see a dozen of the same type of photo from 2 models of cars repeated 7-8 million times on web forums!

As an aside, since the majority of drivers today lease their cars, I wonder if they are using Tier-1 gasoline, as is recommended by the manufacturers.

[wwest]

from a scientific standpoint, I think we first have to consider the fact there are well documented case of carbon buildup in non-dfi engines as well. There are pictures of this type of issue that predates the widespread usage of DFI in non diesel engines. So, we have fact #1, and that is that non-DFIs have this issue as well.

Another issue: Most of the horror pictures are taken of VW/audi products such as the VW sourced Cayenne or the ubiquitous 1.8/2.0 DFI-turbo motors. I believe that a few plausible theories are floating around now concerning the EGR valve and the angle of the injectors. If they were all this bad, why would VW continue to produce the design. The liability would be too great, would it not?

I am also not convinced that the technology itself is faulty, but rather the application of such technology in certain vehicles or circumstances. We are seeing the vast majority of new vehicles move to this technology, which was mass produced since 1998 in the japanese market, and then went on to become the entire european market in recent times. The companies that are investing in this technology would have noted these doomsday issues long ago and would probably avoided the systems, in the way that Rotary engines became curiosities in the 70's, but eventually fell from the face of the earth. (sorry mazda RX-8!!) So we have 20-30 million of these systems on the road today and scarcely a new car can be found without the tech. Engineers are just not that silly to ignore such problems if they were inherent and unavoidable by design. We have also not seen the massive number of vehicular failures that this theoretically flawed technology should in fact be producing! More so, we just see a dozen of the same type of photo from 2 models of cars repeated 7-8 million times on web forums!

As an aside, since the majority of drivers today lease their cars, I wonder if they are using Tier-1 gasoline, as is recommended by the manufacturers.

I would much more readily believe that picture is the result of an ordinary, "standard", intake valve stem seal failure. Anyway, just when did the Cayenne engine adopt DFI..??

[wwest]

Take a look at this THREAD discussing severe gunk buildup on Cayenne DFI engine's valves.

Will 997.2's 9A1 engines develop this?

Hmmm...

Look closely at the area of the intake runner below the valve stem. See how CLEAN that area is..??

Seems to imply, for me, a valve seat leak in that area.

[wvicary]

Cayenne 2008 3.6l V6 is the first year of this engine that I know of. I'm not sure of the other models or years.

[geoff]

The normally aspirated and turbo V8 Cayennes also first got DFI in the 2008 model year