AFRs going 100% lean within 10-15 seconds of start

[swiftmkiii]

So, after a fairly solid tune and otherwise running well, I had something strange happen.

Friday, 15 mile drive home was uneventful as far as tune, and the car running.

Saturday morning, start car and begin driving. Within 5 minutes, the thing is acting like it is running out of gas (fuel pump is running fine).

Current repeatable startup symptoms
Turn key "start", then release.
Innovate LC-1 sideband indicates 7.4 AFR while O2 sensor heats up.
Wideband indicates 12-14 ish AFRs for a couple seconds, then the AFRs start climbing to 100% (21.9 indicated) over about 6-8 seconds.

The car will run as long as the wideband is in warmup mode. As soon as the AFRs start to indicate anything, the car stumbles and dies.

So far:
I have done a true free air calibration with the O2 sensor out of the exhaust pipe.
Verified the fuel pump and relay are operating correctly.

I could really use some help determining what is going on.

Tune and datalog attached.

[grom_e30]

both your map and baro sensor readings look odd with engine off map sensor reads max of 77.8kpa and you baro sensor reads from 70kpa all the way up to 233kpa.

[swiftmkiii]

both your map and baro sensor readings look odd with engine off map sensor reads max of 77.8kpa and you baro sensor reads from 70kpa all the way up to 233kpa.

Thanks for the direction. It is in fact the pressure sensors. The next question is why?

I build the MS2 with the standard 2.5 bar sensor. I added another 2.5 bar sensor with the capacitor and resistors to use it for Baro correction. It has been running fine, until recently. Now, if I turn off the "Two Independent sensors" baro correction it runs fine, and the Map sensor is used for MAP. If I turn on the second sensor, the free air sensor is used for MAP, and the sensor attached to the manifold is used for baro.

[grom_e30]

are they sharing the same source for power and ground ect??

[swiftmkiii]

are they sharing the same source for power and ground ect??

The MAP sensor is attached to the board, in its typical location. I pulled power and ground for the Baro sensor from the proto area. Both are located in the case.