Trims not responding


Nov 5, 2016
Los Angeles
I have an issue where under light throttle trims will stay at 0 and AFRs will slowly go up to around 18-1 before the trims kick in and take AFR back to target. Usually, it’s only bank one trims not responding but I’ve seen it happen with both banks.

All four 02 sensors replaced 10k miles ago. Index 12 injectors were done within 30k miles. Reset adaptions. Swapped tmap sensor back to stock for the hell of it and problem persists. Happens on stock tune and custom tunes. No codes.

I also have a trim variance up to 10% when WOT and 5-10% while cruising. Car is DI only. New valve cover and gasket within 5k miles. I believe this to be unrelated to the trim flatline issue.

Any thoughts? I’m leaning toward swapping the 02 sensors again but I’d be surprised if they went out within 10k miles with no codes.