Postby patrickm » Sun Aug 28, 2016 2:31 pm
I've also been getting about 11-12 mpg around town (US gallons) for the past month or two. tried running w/o the a/c, there was some improvement, but over the winter with the same driving routes and the winter blend gas i was 14-15. (on the highway i'm still getting 20-21 with the a/c on full time, so that's fairly similar). but i seemed to get better mileage in short test drives in open loop mode than closed.
i have no codes, but have been watching the A/F sensors (upstream oxygen sensors), using the Torque app, and noticed occasional slow/erratic response, and that all but one of the sensors (B1S1) were reading in the 0.9v range, with B1S1 in the .4-.6v range, which i thought was normal for the front sensors. After a swap while doing my brakes, i seem to have a bit better acceleration, and it's too early to tell mileage changes, but i still have similar ranges in torque. I know there are issues with how those OBD-2 readers report certain signals for certain brands of vehicles, so could someone confirm on their pathfinder (who also isn't getting 12mpg city) that these levels are normal in torque?
i'd post a picture, but the board does't seem to let me. I will say that the two sensors i pulled looked different from each other, and one had some discoloration probably from heat. One looked similar to the Denso's i put in, but the other had a different shield around the sensor element.
for LTFT's, one bank around town is about +3%, the other is about -0.8%. on the highway, they can get to as much as 6.2% and -1.6% for long, steady drives.
i swapped out the PCV, and most of the crappy looking hoses. i compared it to my brother's 2011 a few weeks back, and it was pulling similar vacuum at idle and 2000 rpm. (he doesn't have the scan tool or live nearby, so i can't check his o2's)
any thoughts on what may be the source of the sudden drop in mileage, verification of what working AF's look like on torque, or ideas what else i can/should test would be appreciated.