this has happened before i put in the new pump or redid turbo setup

stock + utec i tuned it to where i wanted it, then a few weeks later the afrs went from about 11.7 to 1 to about 10.2 to 1 .......i retuned to 11.7 to 1 then about 1 month later it went lean again to about 12.7 to 1....it was in the summer so ther was no wild temperature changes

today it went lean again to about 12.7 to 1 even with cold weather it shouldnt go that lean should it-------------or should it
is any one else having this problem......
could it be the pump or the utec.....

 

If your running open loop boost control, or an MBC, then any increase in air density, whether it be a high pressure weather pattern, or cold weather will cause the car to see slightly higher boost, the result would be a slightly leaner AFR in some circumstances.

If you have been logging data you should look at your load sites and duty cycles, if the load site, and injector duties are the same, and the boost level is the same, then you can look at fuel pressure..