Just rebuilt my engine on my 03 G35. It is running lean on bank 1. Lt fuel trims at 129, short term is almost normal. I smoke tested it and couldn’t find a leak. Any help would be appreciated

Update checked spark plugs on bank one and doesn’t looks like it has been running rich. I suspect a lack of fuel condition. I swapped injectors to see if it would move but not so far.

P0171 (Lean Bank 1) showed up about a month ago. I did everything:

-Replaced fuel injectors (had a set of factory injectors)
-Cleaned then replaced MAF sensors
-Replaced intake manifold gasket (found a mouse nest under the manifold)
-Replaced the Bank 1 A/F sensor (i.e., pre-cat O2 sensor)
-Smoke test - no leaks
-Disconnected the battery for about an hour

The LTFT is under 10%, but still elevated in comparison to Bank 2.

It usually takes a couple of days to throw the CEL, but I am scanning regularly for pending codes. Nothing yet.

Next step: replace the fuel damper assembly on the Bank 1 Fuel Rail if the LTFT keeps rising.

Since I am not running lean on Bank 2 (i.e., no P0174 and LTFT is close to 0%), I'm ruling out a bad fuel pump. However, if the Bank 1 fuel damper is clogged, that may be restricting fuel to those injectors.

Let me know. I’ve tried swapping injectors
Between banks. I also replaced af sensor bank 1. I am starting to get a miss on cyl 1 so I am suspecting a bad injector. Maybe the regulator is bad?

Checked fuel pressure it is good at 51 and steady under load. Reset fuel trim and it is just slightly high on bank 1 st is 106 but goes down to 98. Long term is perfect stays at 100. Bank 2 goes between 97 and 102 st both are within spec. Idk why but fuel trims are normal now. Maybe it needed a hard reset after I replaced o2 sensor. New problem intermittent misfire. Only in gear sitting still can put in park and it goes away. Doesn’t mis at all at any other rpm. No codes.