I find that perhaps 6 ports are apt to disfunction. Are they known to fail? How do they fail? Clogging? I assume mine work, the car accelerates smoothyly all the way to redline. Please give more info on 6 ports.

 

Usually carbon buildup causes them to get harder and harder to move until eventually they get so hard to turn the actuators no longer have enough power to do it.

 

if you want to test them, put some grease on them (this only works for s4) and do a redline run. If the grease is all smeared, then they're working. On an s5, try just bypassing the solenoid (the furthest forward one on the top rack) and rev the engine to 4-5k, the actuators should then move, they do on mine anyway.

 

I like that grease idea, thanks.