I scanned my truck last Saturday and data logged 5 different runs. I then tried it again this Tuesday and I am now confused. My WOT o2 readings on Sat are different than they were today??? I did not change anything. It is a lot cooler today then last Sat and my AIT's were low compared to Saturdays runs (avg. 90-110 deg today and 120-130 on Sat.) Could the temp have an affect? On Sat my o2's were around 940 mv. Today they were in the low 900 mv's????

I also have an STS turbo on my truck. My boost seems to fluctuate from day to day. Some days it will never hit 5PSI at WOT and other days it goes to 6 PSI + at Wot. What could cause this. This may be why my o2's are all over the place!!!

 

My o2 readings fluctuate alot also. The whole time my wideband stays the same. That's why you can't trust o2's for tuning.

You also could be maxing your fuel system due to the lower temps and more dense air.

You should have a look at your injector duty cycle (pulse width) to see if they are maxing out. Are your injectors stock?

 

No I have 43 lb injectors and a Walbro 255 pump. What you said is probiably correct. Allen at Nelson Per. is doing another PCM for me as we speak. I was just curious as to the fluctuation. I just got my Autotap and Im trying to figure out how to understand all those numbers!!!