I have a weird problem with my EFIE not allowing my Air Fuel Ratio to run lean. I can tweak the first O2 voltage to make it lean the Gas ratio however after 4 or 5 minutes, it re adjusts itself to run rich.
Im in the middle of tweak the MAS air flow sensor to make it seem like its getting less air.
Also I placed a EFIE on the rear O2 sensor to make it seem like its running rich to compensate for the lean burn.
Both aren't getting results, Im using a A/F gauge to judge the ratio, after adjusting it shows a lean mix but after a while its bounces at 14.7 again
Anyone else have problems with this? This is on a 03 Toyota ECU 1ZZ engine