fuel trim question

[capnfred]

I have a 96 Ranger XLT with a 3.0 v-6, recently started using an ultra-guage which lets me monitor various engine parameters. I don't seem to have any issues, no CEL, no drivability issues, starting or idling... I have been monitoring various parameters, w/o fully understanding what I am looking at... but am learning all the time, I started monitoring the LTFT (Long Term Fuel Trim), and see a difference between the two banks. one consistently reads different than the other... my question is should they both be close to each other.... (which BTW makes sense) since one is for the front bank and the other is for the back bank... the o2 sensor for Bank 1 is new....the other o2 sensor is at least 5 yrs old.... I get about 21 mpg avg. any advice or comments are appreciated...

Fred

 

[SMTGREG]

LFT can vary from side to side for several reasons like flow pattern or rate of injectors, vacuum leaks or what you have is a difference in o2 sensors. Bank 1 is always the side with the #1 plug. If you change something clear the Keep Alive Memory (KAM) since the LFT is a learned value from last reset.