DanielRicany

Hello. I watch my AFR gauge and my laptop. When my computer switches from open loop to closed loop, the AFR gauge goes to 18:1 and drops down to 14.7:1 as the integrator moves up.

Anyone know how I can correct this?

It is on a 1985 Corvette with '870 ECU. Thanks.

bjankuski

Look at the MAF tables where the engine (When the engine switches from open loop to closed loop) is operating and make them richer (more air). What this tells me is your open loop fuel tables are adding in additional fuel with the load and temperature tables, when you transition to closed loop those additional fuel adders are eliminated and the O2 controls the fuel trims, since the MAF tables are too lean at that transition point the car goes lean until the intergrator takes over and makes an adjustment.

If you want to dial in your MAF tables very closely, it takes time but you could warm the car up and then force the car to run open loop and zero out your fuel adder tables for load and temperature and then tune for a 14.7 AFR at light and moderate loads, then put the car back in closed loop. That will assure you that your low to moderate load MAF tables are dialed in correctly and then your transition to closed loop will be very smooth on the AFR gauge. This will more then likely require you to retune your open loop fuel adder tables for load and temperature to hit your desired open loop AFR of 12.5 or so when the car is warming up. (time consuming but if you do this the car will run like stock or better)

DanielRicany

I think I figured it out. It was having a lean transition to closed loop because I had uploaded a new tune, so that must have reset the BLM.

When I let the car learn the BLM, and attempt to transition from open loop to closed loop, the transition is good.

However, I did notice that in different weather conditions, the BLM changes. Anywhere from 118-136 at the same RPM, same MAF gms/sec, just on different weather conditions.