Hi there, new to the group.
I know this is a 10 year old post, but my googling of my car issue brought me to this exact topic.
I have a 2019 WRX that was tune during the winter FEb-March of this year(93 octane and E60).
I have an AEM fuel pump,Catch can,CAI, and Jpipe installed with separate tune for 93 octane and E60.
During the winter, I was running E60 tune, no code will pop on my Cobb Ap, no matter how I drive my car.
This summer, code p0171 came up on my AP. I sent logs to my tuner, and he gave my an updated tune for E60, But p0171 still came up.
He then told me I have an air leak.
I smoke tested my system but found no leak.
I then changed my tune back to 93 octane and filled up my tank with 93, and reflashed my tune.
The code p0171 never came up on my AP.
I read Spamby's post above, stating about the ethanol changes during winter and summer.
Is this what my car(tune) is experiencing right now?
I can send logs here if someone can look at them.
Regards