Long term trims take a bit to reset. They are updated every 2 min, but for each rpm and load range you are in. You might want to do the full/hard reset at the battery to see if the trim matrix goes back to zero. I think the official procedure also calls for idling 2 min as well and then staying on the brake, in "D", with some rpm (1,500?) to pre-load these often used trims (high load, low rpm, like off the line at a light).

Best of luck, keep us posted.

 

Did you try this as I pretty sure you have a substituted value

 

Any news ?

 

Ha, no news is good news?

The Android 11 update killed Torque (the OBD scanner app), and I haven't gotten around to finding a good replacement yet, so I haven't been watching the trims.

Well, and then I was distracted by a different vehicle misfiring, so the XK8 is off my plate for the moment.

 

Speak of the devil, the Torque app released an update that fixed its crashing issue, so I was able to check the fuel trims yesterday.

No luck. I still have -15 fuel trims on both banks when warm and sitting in park.

The O2 sensor looks much more lively though, so maybe that improved something else somewhere else. I had also worked really hard to make sure the MAF sensor connector was clean, using electrical cleaner and seating it a few times to try to scrub out mating surfaces, but turns out that didn't help either.

For the moment I'm busy working on another car, so it will be a while before I focus on this again and figure out a plan of attack.

 

And the IATS reading with just the ignition on....?

 

73.4, which sounds reasonable to me.