So I have a g35 2007 sedan that’s tuned through uprev and I’ve had a lean code both bank 1 and 2 for a long time now and it came shortly after I installed test pipes too my car so my first thought was since I have a full isr exhaust plus those test pipes and after market short ram intakes that could be the reason and a tune would fix it. Well after tuning my car my tuner told me that it’s something wrong mechanical and that I would have to go get it fixed somewhere so after multiple shops I’ve went too and then just charging me money to “look” at my car and clear the code and give it back too me I was looking for some advice on here to be able to figure it out myself. The long term trims are at +37 for both banks and short term for both sits around +27. Now when I’m at WOT the short term trims drop too 0 until I let off of the throttle then they will spike back up and there is sputter at low rpm’s and it has a high idle aswell. I’ve tried to look it up and from what I lve searched it should be something with how much air the car is getting and not fuel but I’m not sure any advice or expertise would be amazing

 

What's your fuel pressure sitting at?
at idle and under load?
Have you checked for intake leaks?
Spray or pressure method?
Exhaust leak before the O2 sensors could cause a false lean reading...

 

I haven’t checked for fuel pressure yet not Sure if the shops have. I have however paided the shop to specifically check for any vacuum or air leaks by smoke test and they say there isn’t any. Not sure if that’s true or not. And I’ll have to check the exhaust myself. Any advice on how to do so? Talking like header area

 

An easy way to check for an exhaust leak is to use a shop-vac. Youtube has lots of videos on how to do this.

 

Your trims are extremely high. It definitely seems like you have a leak somewhere past the MAF sensor or an exhaust leak.

Other ideas that come to mind:
Do you have any other codes?
Which O2 sensor is reporting lean? is it the wideband or the downstream sensor?
Have you tried cleaning or replacing the MAF sensor (or both if its the HR version)?
Have you looked for cracks in any of the flexible intake couplings?
Throttle body and/or intake seals bad or components not completely tightened?
Injector or fuel flow issues?

Are you using the tuner version of UpRev? (this would allow you to make adjustments yourself as opposed to having the tuner being the only one allowed to do adjustments)
If that is the case, one thing you can try is to increase the values in the fuel compensation table. From reading your write up, it seems to be lean through the entire power band, so you could just do a blanket increase and go from there.
A better way to do this would be to reset the ECU, then begin a log on a normal short drive that goes through all the gears and see what STFT is like during normal ops. Then review the STFT log and note where it goes lean, that would be the area (RPM and throttle body position) that would need enrichment. - all this is assuming there are no mechanical issues.

Only other thing i can think of is to post your concern on Nissan 370Z Forum (the370z.com and/or My350z - Largest online forum for the Nissan 350Z and 370Z. and see if someone there could help you. There is a much larger DIY tuning community active on those forums then on here. (most of the tuning discussions here center around UpRev vs ECUTEK)

Keep us updated!