This will be a long read, please bear with me.

I have 19T's, 550cc injectors, a fuel kit and pump to handle it all, FMIC, and pretty much every supporting mod I need to maximize the 19T's potential on pump gas. That is my goal.

I know the ARC2 is wired correctly. The HHH datalogger shows all of the signals that the ARC2 modifies, and I can see and feel the changes of the knobs.

I had to change the knock sensor last week (what a bitch that was), and when I put it all back together I forgot to connect the driver's side crankcase hose, the one that goes between the heads. When i got the car back together and started it, I was amazed at how well it idled. I attributed it to the new colder resistorless plugs and MSD wires I installed while I was doing the knock sensor. I took the car out and got it tuned to the point I could go WOT at about 1.1 bar (~16 psi) and get no knock, and it idled and cruised nicely. I was happy. Yesterday I was vacuuming leaves from the engine bay crevices and found the hose and connected it, and took it out and that's when the problems started. What could this mean?

I can get it to idle correctly and cruise nicely, but my problems are when I get on it. I was under the impression that the ARC2 needed set per injector size, and once it was set you could vary the boost however you wanted and not touch it again. Is this assumption incorrect?

What happens is the AFR begins to lean out at higher RPMs, about 5000+, and I get knock. If I go clockwise on the high knob, it gets stable longer, but then midrange driving (about 3000rpms, half throttle, not even positive pressure boost) gets pig rich. To correct that, I'll give a click to the mid knob, but then my throttle response goes to hell and I get stumbling.

Where am I going wrong? It worked nicely when the crankcase vent hose wasn't connected... why would it do that? Should I pick up some of those $140 krank vents? My ARC2 says it's the GP R5 version via a sticker on it, but the sticker is hand-written... could I have gotten a crap version?

Any help at all is definitely appreciated, I really want to get this going.