Just a heads up for other beginner tuners.

I've been running an AEM Uego wideband gauge in my car (93 Buick wagon) for a couple years now. Initially it was to get my full throttle and AE tuning in the ballpark. Once that was dialed I left it in. Looked kinda cool and the narrowband output to the factory ecu meant it would work fine in closed loop, which it did.

A few months ago I started noticing in highway mode the car would start leaning out to 17.5:1, to 18 then dots on the meter, so I turned off highway mode to see if that fixed it. It got better but then it just started going lean on the gauge after running for a while (20+ minutes) on the highway at steady speed. Couldn't be the fuel pump I thought, it's still hitting 12.5:1 in power mode.

Finally this week I hooked up the logger and noticed that while the wideband was showing lean, it's narrowband output was showing rich!
BLMs were dropping slowly to 108 (minimum in the tune, would turn on the service engine light)!

I cleaned the terminals on the gauge, and it's working fine again. Kinda amazed at how well it ran with so little fuel. Didn't gain any mileage, and I'm sure it was knocking a bit, but it ran fairly smooth!

I can't stand little gremlins like this, I ran through at least 10 tunes trying to track down why it was leaning out. Wanted to give my little bit back to the group.

TLDR: AEM Uego gauge narrowband output might drift high on you, tricking the ecu into thinking it's running rich and leaning things out. Dunno if it's just a dirty contact thing, but it's what I came up with.

Happy tuning travels!