TomBelgium

I know, i meant that it is easy for Porsche to replace the cilinder walls in their new engines during the building process. If you want to repair your existing problem (forever) with better walls and pistons prices are about 5 to 6k euros. But that excludes removing and rebuilding the block in the car. It makes me think completely different about the Porsche brand then a month ago before i knew all this. So sad for such a financial healty brand...

Yeah, I am selling my S too after just one month of ownership. Maybe I buy a 3.6 cayenne (VW VR6 engine) but for sure I don't buy another Porsche with an Engine built by Porsche. A lot of people say a BMW X5 is nothing against an Cayenne and I agree in terms of driving experience but at least I don't have to worry about engine failures when I go on holidays with an X5. With the Cayenne I would never be relaxed taking it for long road trips. Such a shame, I expected more from Porsche and I was really happy the first days I had it until I had the HPFP failure and especially now with all the people I talked to who say Porsche engines are way worse than everybody thought.

I hope so, i found some companies on the internet that delivers stronger pistons and cylinder walls. It seems like a simple fix (for a manufacturer like Porsche), i just don't get it why they didn't changed the cylinder wall material after the first failures back in 2003-2004. BTW my engine was also replaced before i bought it at 40k kms for the same known cylinder issue.

I used to work for a second hand (exclusive) cars dealer. I remember we sold a quite new Panamera with a 4.8 engine after a month it came back with cylinder scoring. And i talked to a few people who owned a Porsche, also 911's, and about 9 on 10 people told me their engine was replaced by Porsche before it even reached 100k kms. Some of them were happy about it and told how good their service is because of receiving a new engine. Of course it is the least they can do, but i do not understand how they have the exact same issue with multiple engine models for almost 2 decades now.

So Porsche sold/built bad engines for years?

Hello, I recently bought a Cayenne S 4.8 from 2008. After a month the HPFP went down so I repaired that (900 euro), no problem if it is just a standalone incident but it seems to be very common for the 4.8 engines. Mine was already replaced with the former owner in 2010 and 2011. My engine was replaced in 2010 by Porsche and now this engine has around 100k kms (so the second HPFP failed just after a couple of thousand miles). This made me thinking about the build quality of the Porsche engines. The HPFP is not Porsche made I guess (Continental is written on it) but if "I would be" Porsche, I would look for another manufacturer for these parts. So I already got the impression that they are not as typically German as I thought. Then I got in touch with other Cayenne owners over the internet/facebook etc. And the first 10 owners (with a 4.8 engine) warned me for cylinder scoring because they all had their engine replaced or sold their car because of this problem. I knew the 4.5 had this problem but I remember calling a Porsche dealer a couple of months ago to ask if the 4.8 was better build and they said it didn't have any issues like the 4.5 had with the cylinder walls. So I checked again why my car had a new engine and indeed, also mine had scored cylinder walls at the time. Some people say it happens because of starting the car in freezing conditions but in Belgium, it doesn't get that cold like in Alaska or Scandinavia. I suspect just a bad build engine or the wrong use of materials for the cylinder walls. It would be nice to know how common this is on the 4.8. I am very interested in how a car works and why an engine can fail so I would like to know who has or had an Cayenne 4.8 (S, GTS or Turbo) and if you ever encountered this problem.

Update, didn't want to spend more time on fixing the pump so I bought a replacement for 900 bucks. Porsche told me they already replaced it a couple of years ago. I tried to explain that it is not common for a quality car to have 3 different HPFP in just 100k kilometers but they didn't agree. My former daily was a "boring" Skoda Superb diesel, I only had to do regular maintenance, and it had even more kms on the clock than the Cayenne. I am selling my Cayenne now because I also heard about the cylinder issues. My dealer reassured me that only the pre facelift 4.5's had cylinder issues. But I spoke around 10 cayenne S 957 owners and they all had the cylinder issue. Also mine had the engine replaced at 40k kms, right now I am just waiting for it to break again. I also drove a BMW 850i V12, I always heard people telling about that they know somebody (friend of a friend of a friends cousin etc.) who had an 850i and it should be rubbish. It never let me down, not once I had anything unusual to repair. But with the Porsches, just open a topic in an owners club or on any car forum and you get dozens of owners who have or had an engine replaced, cylinder issues, bad bearing in the engine etc. It was my first Porsche and I didn't expected it to be cheap or whatsoever, I just expected it to be reliable but they just are not. I really hope that Porsche does an effort to bring the quality back like it was in the 80s and 90s.

I bought a new hpfp, installed it myself and all ok now.

Yesterday i took my HPFP out and opened it. I tought that it could be some worn o rings. And indeed, the o rings on the check valve were cracked, so all pressurized fuel leaked back to the low pressure fuel system. So today i bought some new o rings in a specialized store. Put my HPFP back in and tried to start the car. It took as long as before only now the rough idle was gone. Unfortunalty i got a check engine light, the p1023 and p1026 errors and a lack of power above 2000 rpm. Seems like my pump is completely dead now. But the obd shows the the high pressure is maintained when the car is turned off. So i fixed the leak but that might have broken the (weak) pump. Tommorow i am going to order a new pump at Porsche...

Anybody?

Hi, I am trying to figure out if my high pressure fuel pump is faulty. I noticed longer cranking when starting the engine, misfiring when it just starts (or very rough idle the first seconds). After revving a little bit it goes back to normal and the rough idle is gone. This only happens when i leave the car parked for a couple of hours. I already got p1023 and p1026 (reffers to high pressure problems) The high fuel pressure (in the rail to the injectors) loses pressure very quickly when i turn the engine off. It goes from the 40 bar it had when idling to around 4 to 5 bar in some hours. It seems like the 4 to 5 bar are is the pressure that the low fuel system is providing so my guess is that the HPFP is leaking the high pressurized fuel back to the low pressure circuit (or mixing). Thats why it never goes to 0 bar but keeps its pressure from the low pressure circuit. Am i correct or is it normal that the fuel injector rail/ High pressure circuit loses its pressure when i turn the engine off? Otherwise i have another problem.

It seems like my actual value is following my setpoint high pressure value when driving or idling. But only after the rough running is over. It doesn't keep the high pressure in the rail, i only got around 4 to 5 bar when the car is turned off. I believe it will be a valve in my HPFP as the low pressure (which should be around 5.5 bar) is maintained (it is normal to drop 1 or 2 bar in a couple of hours).

It drops to 0 bar?

Seems like piwis can give me more useful information about a P1023 that i got. As you can see the actual value at startup is ten times lower as required.

I will check that tommorow, i am leaving the car 24h without starting to check the high fuel pressure to see how much is gone after 24h. Do you know what high pressure value it should have with the engine off? I believe it should be at least 40 bar so it can start easily because the idle requires 40 bar too. I am just trying to eliminate possible failures.