Wow, thanx for posting. First I've seen the valves from a .2 DFI engine at 100K miles. One of those intakes in your pic had carbon right where you don't want it, along the valve-seat interface... this does not mean a performance degradation though.

BTW, that Porsche graphic showing the spray..... what some have pointed out is that the perspective is flattened and you can't see if the spray really is on the back of the valve. Anywho, your pics are truth.

So, why did you do this? Just a good idea? Performance issues? Did you notice a performance difference when done?

Peace
Bruce in Philly

 

Your pics 2 and 3 show day and night differences between prior and after removal of carbon. Perhaps the 997.2 never ever needs walnut blasting, but in your case it is proven that it sure helps. When I originally posted the thread it was an inquiry into whether anybody has ever done it before, but the responses from the forum has more to do with defending the integrity of the 997.2's engine that it never needs this procedure. I've done it with my BMWs and that is why I'm interested in knowing how to do it with the 997.2.

 

As far as I know, 987.2 3.4L DFI has virtually the same engine as a 997.2 3.6L. The 3.8L is virtually identical also.
The data has shown similar buildup on all flat Porsche DFI engines.

I agree with the board consensus. You do not need to clean the valves. Porsche DFI does not clog up like the BMWs which run terrible and throw codes if not cleaned.
I had no serious problems; ran fine, no codes. I thought I would make the car run as good or better than new, rather than just run fine....
Has 1-2% leak, burns zero measurable oil.
It definitely runs smoother at low throttle positions, MPG has also improve significantly on highway only.
I used an accelerometer/oscilloscope I mounted to the engine and identified 3 different vibration frequencies. One is the engine mount that in my opinion are under designed, the other 2 are likely slight engine imperfections. The port cleaning eliminated one of these vibrations as measured via accelerometer/oscilloscope on engine and the butt-meter.

Next I am going to meter the injectors. I have not seen any data on DFI injectors with higher miles.
Anyone know the best (affordable if possible) tools to remove injectors and re-size seals?

Sorry , I never answered your original question: How to clean? Same as BMWs.
Place adaptor in the intake port, connect shop vac, place walnut blast tube in small hole.
Here are the 3D printed parts I designed and printed to blast: 2 versions, center hole and 2 offset holes.