Really bizarre problems. 2004.5 G35 sedan was running beautifully since tuned about 15,000 miles ago (So im not thinking this problem is tune related). About a month ago car randomly lost power at a red light and had a hard time starting up. When I was able to start it, it seemed to be in a limp mode as when i would try to accelerate the car would sometimes refuse and stutter and other then would all of a sudden be ok for a second then lose power until I finally gave up half a mile down the road. Came back an hour or 2 later with my uprev cable, scanned the codes (Shouldve wrote the codes down but forgot) and showed some lean codes and random misfires which i already knew. Cleared the codes and have been driving it about 1000 miles since with no issues.
Yesterday driving to my friends I start sputtering and losing power at a red light, barely made it to my friends house with the car refusing to accelerate except with very very low input, im talking a bunny rabbit touch any more than that and it would start cutting throttle completely and die, almost as though the throttle was being purposely limited to stop lean conditions.

Weird thing is Ive had limp mode before and this isnt it. It doesnt activate a christmas tree of lights on my dash and make it where I cant accelerate past a certain RPMS, this seems entirely different. Since making it to my friends house we tried working on it with the limited tools we had and eventually at 11 pm that night I dared try to make it back to my house. We were able to get the car to stay running and relatively stable by removing the maf sensor completely. With the MAF in the car, it was sputtering like crazy and would almost cut out quite often. Also idling at 500 to maybe 600 rpm max at all times unless it was trying to surge power after dropping to damn near 250 rpms sometimes. So thats how I was able to make it home was by removing the MAF so the car was relatively stable but it was still having the same issues of not being able to touch the peddle more than a feather. Made it home going 15 mph up some hills.

AFR readings are absolutley wild too. Jumping anywhere from 18 to 28. Checked the AFR readings with the voltage outputs of all the O2 sensors with Factory Service Manual and found all O2 sensors to be fully functional. It seems that for some reason I truly am leaning out hardcore. Im going to start diagnosing more tomorrow and replace MAF just in case. If anybody has any suggestions on where I may be getting a vaccum leak from let me know. Or any other ideas on what this might be coming from. The only consistent codes (codes I know are not from me unplugging the MAF) Ive gotten are p1283 (bank 2 sensor 1 o2 sensor lean condition) and C1130. P1283 I believe is not due to the o2 sensor failing but simply how ****ing lean the car is because ive checked the values it should be outputting and they are correct for the target values. C1130 worries me, CAN issues. Essentially ECU is sending faulty data or a blown ECM fuse somewhere. Any help is appreciated, thanks.

 

C1130 is basically just the VDC/TCS computer saying that the ECM is sending out codes that something is malfunctioning on the engine controls system. This is not a CANBUS code, it will clear up when the ECM is no longer throwing codes.

P1283 is the ECM saying bank2 is too lean, not usually caused by the O2 sensor itself but rather because that bank IS TOO LEAN.

First thing I would do is pull the plugs and see what's going on inside the combustion chambers. Then start looking for major vacuum leaks that could be causing that lean shift, there's a really good chance that bank1 is running lean as well just not quite lean enough to throw a code for that bank.

Are you sure you're not just out of fuel? I would get one of those Z1 Motorsports VQ fuel sandwich adapters so you can test for fuel pressure if you do have gas in the car (don't go off the gauge which is prone to failure, actually add a gallon of fuel if you aren't 100% sure what your fuel level is).