v10rick

If so this is a relief.

My GTS is not a daily driver...seems that every time the key is turned I am listening for the dreaded engine knock.

Uses a quart in 5K mi. so with that I am OK with this engine.

Petza914

I think it was actually TomF that alerted me to this fact and hypothesis in one of the bore scoring threads, but seems like it has merit based on the searchable reported failures.

So 09 not only gives you the improved touchscreen PCM, but also a better powerplant, so it seems.

TomF

Thanks Petza914.

Here is what I understand- in the middle of the model year 2009, Porsche told their suppliers (AFIK, there were two in 2008 for the 4.8l Cayenne) to use only the structural cylinder honing process. In MY 2008 and early 2009, one of the two suppliers was using the smooth honing process. In 2014, Porsche released TSB Service 1 25/13 ENU 1010 (Jun 20, 2014) that the combination of the earlier piston ring coatings and the smooth-honed cylinders was problematic. In the event of an engine-scoring issue or engine repair that required cylinder/piston/ ring repair, only the newest rings, which are DLC-coated, and structurally-honed blocks were allowed in combination.

My hypothesis is that after early MY2009, there will be little or no issues of scoring. If a 4.8l NA or Turbo engine has structurally-honed cylinders, I posit that it will probably not fail due to scoring unless there are exigent circumstances, ie. neglect, extreme cold and or abuse. Here is the list of engines through 2014 that have structurally-honed cylinders:

92AAH1, 92AAI1, 92AAL1, 970110, 970111, 970120, 970121, 970410, 970411, 970420, 970421, 970430, 970431, 970440, 970441, 970450, 970451, 9PAAH1, 9PAAH7, 9PAAI1, 9PAAL1, 9PAAL7, 9PAAN1, 9PAAS1

I am certain that this is not inclusive, so no one should panic, but if you have one of these engines, the chances of an issue may be less. I wish I could figure out a way to determine which supplier an engine came from!

I suspect that there is far more to this story.

Cheers,
TomF

touareg

Thanks for the answer guys, I have had mine since about 29k, and didn't realize that this car as far as trim level is rarer than my 968