So I tried this scrub and suck method one of my cylinders today. I did just one cylinder to see if it would work okay. Try at your own risk, I'll let the pictures speak for themselves. The CRC GDI stuff costs ~$15 a can and I'll probably use 2 full cans for all the cylinders, plus 1 can of carb cleaner and a toothbrush. I think I will try the rest of them when I have time.
CRC GDI direct Valve cleaning
1) Turned crank to get piston at TDC, covered rest of ports and engine.
2) Squirted a little bit of CRC GDI valve cleaner directly on valves, watched closely for seepage into cylinder. (Did not see any leakage.)
3) Gave 4-5 short bursts on walls and on valve. Solution foams and looks like it's bubbling. Waited ~1-2 minutes.
4) Used brake bleed siphon to suck liquid out.
5) Repeated step 3 and 4 about 4 times. (About halfway through started using a toothbrush to scrub intake walls and whatever it would reach.
6) Checked that no chunks were visible.
7) Rinsed walls with carb cleaner 2X and sucked the liquid off again. (Be sure to tape straw to nozzle so it doesn't shoot off!)
This first photo is the second cylinder on the driver's side. (Not the actual one that was cleaned, but looked similar.)
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This is the forward most cylinder on the driver's side after treatment.
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This is a sample of what the liquid looks like. . THE BLACK GOO...
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