As the title says, my AFRs are reading lean (via AEM UEGO wideband gauge) showing 12+ at WOT (basic bolt on car tuned on 93 octane). I didn't have time to install my AFR gauge before getting tuned, so the weekend after my tune I went ahead and installed it only to get lean readings. Considering I was just tuned, I figured there was no way that was possible and I messed something up in my install or had a faulty sensor. Now I'm starting to question whether that's the case. So far I've done the following:

Replace AEM wideband sensor
Ensure ground wire has a clean ground
Replace fuel pump relay
Replace gasket between test pipe and stock downpipe and check for leaks (my wideband sensor is in the test pipe so I figured if there's a leak at the test pipe/downpipe connection it would lean out my AFR readings)
FPR hose is ziptied down

Something strange I've noticed is when regrounding the AFR gauge, I unplugged my battery to do so and after that I was getting normal ~11 AFR readings at WOT. After driving for a while and letting car relearn fuel trims, AFRs were eventually back in the 12s at WOT. This leads me to wonder - I installed my boost gauge a week or 2 before getting tuned and had done the same process of unplugging battery for the install. Is it possible my car had not relearned fuel trims before getting tuned and the trims didn't settle until after? I was tuned by a very reputable tuner for what it's worth.

Appreciate any insight/suggestions. I want to sort this ASAP

 

Any tuner worth their beans would turn off fuel trims affecting WOT fueling.

Sorry to hear

 

Thanks for the insight. Like I said my tuner is very reputable and if that’s the case then I’m sure he did.

With that said, do you have any suggestions for what steps I should take next? I’m pretty dumbfounded at this point and it’s driving me crazy

 

If your wot afr is affected by your fuel trims, than they didn’t change that in the tune.

from your description, that is what’s happening.

 

Disappointed to hear that. So essentially I need a retune..

If I had a tactrix cable and EcuFLASH is this something I could fix relatively easily or would it be a **** show for someone with no tuning experience?

 

Well you peaked my interest with this and I wanted to verify. I just disconnected the battery to reset fuel trims and took it out for a drive after. Sure enough AFRs in the 10-11s in 3rd gear WOTs, 11s in 2nd gear WOT.

So is my car essentially only properly tuned on fuel trims that are unlearned to my ECU? And when the ECU relearns fuel trims it leans it out? AKA my tune is ****ed? What a mess..