Originally Posted by gsg740

I used data-logs to compare A/F ratios between Bank1 and Bank2. the data logs show Bank 1 WB A/F is constantly richer than Bank 2 WE A/F. while Bank 1 A/F adj. is around 0.36. So I think ECU must also see Bank 1 is richer.

I think the primary O2 sensor (bank 1 sensor 1) is functioning. because when ECU was reset or WOT, both Bank 1 & 2 WB AFR is nomal. However, after cuple mile bank 1 become richer and richer because ECU adding fuel on Bank 1. Voltage on both sensors are correspending with the AFR and changing rapidly.

uprev only shows one combined MAF and voltage. At least my uprev does not have any bank 1 & bank 2 option for MAF. I checked my intake 3 times already and I also tried to replaced the stock tube by Z1 post MAF tube. but the problem is still there.