I keep getting a P0174 (bank2 lean) code. It takes about 2-4 ignition cycles. And on cold start in the morning the engine misses at fast idle although not for long. I have some scan data here. I'm not too fluent on fuel trims and I hope they are enough for someone to diagnose. BTW-the car runs great with no perceptible difference before and after the code gets set and that's the only code, no other lean codes, no misfires.

So here's the freeze frame data at the time the code was set. Thanks for any advice.

STFT1 1.5%
LTFT1 17.9%
STFT2 (-7.5%)
LTFT2 19.5 %

FUEL RAIL PRESS. 366 KPA
AIR FLOW RATE 32.67 OR/SEC
MAP SENSOR 62 KPA

 

Did you search for vacuum leaks on Bank2 (LH side of engine when viewed from driver's position)?

 

the LTFT's of both banks suggest a sizeable vacuum leak.

Were those values with the engine at idle or while driving / under load?

If it was an O2 sensor you would have high LTFT on one bank only.

 

Thanks, I'll check more thoroughly for a vacuum leak. I tried spraying carb cleaner around and got no change and since the engine ran smoothly and with power, with the exception of the cold start being lumpy, I thought the problem was something else. Last spring I replaced a coolant hose under the SC and replaced the gaskets on the EGR, throttle body, etc. It ran fine until now.

I've got no experience with decoding fuel trims but now I see how valuable the info can be. The readings were saved while the car was being driven [1668 RPM ~32% throttle].

 

In the case of a small leak, it is best to perform a smoke test to quickly find any leak(s).

Most competent repair shops can perform a smoke test, but may require the vehicle to be left overnight to cold-soak.