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You dont really have enough of a graph to say for sure what its "supposed to be doing" and even I have never seen a fuel trim graph from an SR20 so I am not expert either. It would make sense that it might adjust over time- but most ECU have a memory that stores up hours worth of data so a fuel trim might not move very much at ALL while you drive. In other words, it remember from the last few weeks, that in each cell, the fuel trim is a certain place to give the closest possible A/F to make the narrowband move through its center of 0.5volts, and it might only take 1-2% of fuel "trim" to cause the swing, which would be moving cell to cell since each cell has it's own fuel trim memory stored. But this is all just guess based on what I know about other factory computers.
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That's long term trim. Short term trim I believe is supposed to directly respond to the O2 input during closed loop. Speaking of which, I cleared my ECU, and my long term fuel trim refuses to ever budge from 128. Also, do you want more data? I can gather more logs. That one is pretty long though, that's like a good 5 seconds of engine exposure to leaniness.
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I still think you should put some cheap spark plugs in it and try that before doing any more diagnosis. dont even gap them, dont boost the car. Just drive it normal. Even with a .044 gap it will be fine.
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Can you give me a recommendation? Not like I can just walk into autozone and say "Nissan 240sx, SR20DET".
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It might be sucking air from somewhere. An enormous vacuum leak would cause that. Did you pressure the plastic inlet tube in front of the compressor? between the maf and compressor that plastic tube always leaks causing problems.
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I pressurized it from the MAF. In other words, I pulled the MAF/Pod filter combo off, and stuck my tomato sauce can in there. There is a boost leak somewhere I suspect, but it's so fucking tiny I can't see the smoke coming out.