My lc1 wideband was reading 2-4 points too rich after the last track day and after a lot of searching with limited success I decided to replace the O2 sensor. That didn't fix anything. After going through all the wiring for the lc1 I found out the hard way that when your IAT sensor gets disconnected the IATs get super cold and MS runs rich. For some reason I didn't think to check all the other sensors in megatune. Thankfully, there are other people on this forum local to me who know their stuff and found the problem before I replaced the lc1.

Hopefully this post helps someone else who sees the same problem.

 

I recently had this problem as well. One of the wires backed out of the connector and I believe MS reads a default value that just dumps stupid amounts of fuel in.

It was really hard to drive with 10:1 AFRs at light load...and harder to uncrimp and recrimp those pins at a gas station at 10pm.