Ahsai

Hey, thanks for the tips. I'm also a Renntech member just didn't know this document until you pointed it out. Reading it now! nice
Exactly the info I was looking for.

blee321

I had a recent fuel injector failure at 3000 miles. I've attached in invoice maybe someone can decode it for me.

P0rsch3F113

I'm hearing that carbon buildup may be a concern on DFI engines.

jhbrennan

Good - another report with no facts.

CAVU

In another thread this was brought up and the author presented a link to a product to solve the problem and later presented links to articles on the web. I read them and still wasn't seeing enough substance to draw a conclusion either way. The only article that I've found that is worth reading is http://www.edmunds.com/autoobserver-...-adopters.html . It's a long read but the author(s) do address Porsche briefly and favorably.

My conclusion is that there is not an issue with carbon buildup with Porsche DFI engines:
- Based on what I've read to date
- There is not a dedicated "I hate Porsche DFI engines thread" here at Renntech with multiple tales of issues
- How long DFI was most likely in RDT&E and testing at Porsche

Who knows what the future holds but I for one think its bright for Porsche DFI.

jumper5836

Cylinder scoring?
Does anyone have technical data showing how DFI works. How does fuel get from pump to the injector, with close to 2000 psi will fuel lines hold up in 10 years?

Spyerx

Have not seen any tear-downs, pictures, or detailed info on this with Porsche engines that they are affected by this problem.

I have an R56 Mini cooper S and this is absolutely an issue with these engines. The fix is simple, and not terribly expensive to do. We had to do one at 35k miles. I've heard of similar issues with other DFI engines due to the fact that fuel doesn't spray over the intake valves to keep them clean.

As a result, there has been an assumption that the .2 engines are going to suffer from this.

I'd love to see some intake valve pics on a .2 engine with 30k+ miles to see if it is...

wwilliams88

No photos, but from the Edmonds report in post 50

"All modern gasoline engines return some crankcase and exhaust gases back through the intake manifold in order to help control emissions, but, according to Chick, some exhaust-gas recirculation designs are “dirtier" than others. Some, he said, are less-effective at preventing the passage of tiny bits of oil, carbon and other particulates that eventually get baked onto the intake ports and valves.

Chick reached his conclusion after inspecting dozens of different DI engines at his shop and finding some, like the V8 in Boyadjiev’s Audi RS 4, regularly choked with carbon while others, like the DI version of Porsche’s horizontally opposed 6-cylinder, remained much cleaner."

P0rsch3F113

https://rennlist.com/forums/997-gt2-...n-buildup.html

I wouldn't think Porsches would be affected much by this issue. As it stands now, it certainly doesn't make me think about NOT getting a 991S.

jumper5836

Cayennes have been DFI since 08 and their owners put more miles their trucks then does the usually sport car owner. There would be a ton of issues popping up in the forums if there were problems with build up.
Leads me to believe that Porsche did something better then other car manufactures are doing that are having issues.

jhbrennan

But this is info on Audi's posted in the 997 GT2/GT3 forum where DFI engines don't exist.

stefang

Turned over 40k this am. Owned the car for 7k. HPFP was replaced under recall, but otherwise engine's great (rest of the car too).

Ahsai

The regular fuel pump supplies fuel at 5 bar to the HPFP, which then supplies up tp 1700+ PSI to both banks of the engine via metal pipes, not hoses. High pressure is released when car is shut down. Also, even if the HPFP fails, the engine can still work from the 5bar for a short time with reduced power. Pretty impressive design.

Btw, diesel pressure is even higher, much higher.

See here for the 180+ pages technik article if you are a Renntech member
http://www.renntech.org/forums/files...arrera-models/

jumper5836

Thanks

dpron

Just passed 57k miles on my '09 S 3.8. Fuel pump replaced around 48k under warranty campaign, not that it was actually busted. Other than that zero issues and it runs great. Some track miles and plenty of spirited driving in there too, not just highway cruising. She often sees the other side of 6500RPMs and seems to love it!