Stft going lean at start up

[SHMUSTANG]

many thanks in advance for any help. i have a 4.6lt kenne bell supercharged 2005 mustang gt and ever time i start the engine hot or cold the STFT leans out with in about a minute the STFT settles down to around 14.7 can anyone let me know what is happening and what i can adjust to hopefully stop this. i am a novice tuner many thanks

[Auto-Hentzschel]

post your tune and a logfile too!

[SHMUSTANG]

many thanks i hope i have managed to up load the files

[Thatwhite5.0]

Swap your bank 1 and 2 upstream o2 sensors and see if the problem goes to the other side. The only time I've seen this was a bad o2 sensor.

[SHMUSTANG]

many thanks i kind of discounted the sensors as they are nearly new but i will give your suggestion a try thanks

[Thatwhite5.0]

Did you figure it out?

I thought the same thing, searched for a problem for months on my car, not exaggerating. Long story short, 3 months later I found I had purchased a faulty motorcaft o2 sensor. Could of been damaged in shipping.

I had a 2010 3v just recently do what you're saying. Start up would be decent but with in seconds, stft bank 1 would lean to 65%, and bank 2 was following right behind. Sometimes you could tap the pedal Sometimes it would go lean while driving and the exhaust would pop from being lean. Sometimes it would drive pretty good but the idle was always poor. Throwing p2196 and 2197, o2 circuit codes.