IS250 AWD 2007 111500 miles
I purchased an ODB2 scanner to get rid of a couple codes due to not screwing on my fuel cap. I noticed that my LT Fuel Trim in bank one is around -5% and in bank 2 around -7% when at idle after a trip. The highest I have seen bank 2's LT Fuel Trim is -2.8% during acceleration. Does that indicate some sort of small blockage - I was thinking maybe the airfilter but bank one gets as high a -0.08%. Neither of them ever measures a positive value.

 

Those are pretty solid fuel trims. Though you should pay attention to the shorts for troubleshooting.

The closer to 0 is ideal.

 

Ok thanks. I really know next to nothing about cars/powertrains. I thought maybe bc the LTFT didn't move past 0 into the positive that perhaps the indicated some external issue that was biasing the fuel delivery to be slightly rich. While driving the the STFT are usually less than 10% in magnitude, but very occasionally I saw them bumping up as high as |15%| while I was driving.

 

This dude explains it pretty well. There is also a ton of sites online of web pages dedicated to fuel trims. You can read on how fuel trims work to get a good understanding. It's a must if you you like working on cars.