How to force OPEN LOOP mode on OE ECU??

[maxthehax]

Hi guys! I dont know if Yaris ECU would work the same on this topic but lets try...

I don't think its a surprise if I say that toyota ecu are complicated...

I run on a FI/c, the car was tuned on a ''acceptable'' level, by modifying the volts sent to the O2 while closed loop. Everything was fine for a while...

Someday, I step in my car, go for the routine drive and bang 17:1++ air/fuel, I was barely able to cruise and accell... tried reseting the ECU by unplugin battery for 10mins, still the same...

hookin up the laptop to the fi/c , nothin has changed execept I saw 0volts on both O2, just like 02 were not working anymore so I had to add some fuel in the fuel map to get richer... weird

now I am about to retune the car to get something acceptable on open loop with only the fuel map. I dont want to do so and bang O2 starts to work again lol :P

So here is my question, is there a way to make sure the OE ecu go automatically in open loop??

Unpluging the OE O2 sensors?
If FI/c is in voltage mode for O2 and I put 0 everywhere?? I think that idea doesnt work...

Thanks for your help!