S14 sr20 sensitive to weather?

[chau]

I had my car tuned in mid June and it was running perfectly. High 10 to low 11 AFR at wide open throttle. Last week while running some logs, it's now running 12.9-13.5 AFR at wide open throttle. No vacuum leaks as far as I can tell. Do you guys also experience this with changing weather? Also, I live in the northeast so it's much cooler now compared to 4 months ago.

Edit: I'm running a Z32 MAF.

[Fast Guy]

Have you checked your fuel pump voltage/pressure? It's now running leaner so might not be getting enough fuel.

[Matt]

MAF measures ambient temperature when offsetting against amount of airflow cooling the hotwire so that is taken into acccount. If the MAF is measuring lean or you have some other fueling issue (like fuel pump measured above) then it may be this

Also check your AFR trimmings (AF alpha gauges) to see where those are at