Issues after ecu upgrade

Hey guys I need help.

Engine 1jzgte We have upgraded the ecu from haltech sport 2000 to the elite 2000 series , with the same existing wiring ,upgraded from 6 to 12 injectors 2200cc each. As well as the turbo from precision 7675 to 8685 sportsman . Transmission th400 with transbrake

We have successfully made 1390hp on the dyno however when stepping on the transbrake and engaging the nitrous ;establishing issues , loud popping sound , the plugs indicating somewhat lean mixture however the aem wideband shows the mixture is still rich. Fuel e85

Is it that the afr guage cant read the mixture fast enough? Or the current draw is too large during staging with the transbrake solenoid and nitrous solenoids? Engine do not have an alternator

Any help with fault finding and defect elimination would be deeply appreciated.

Are you measuring and logging the ECU voltage? What is the voltage when the solenoids are active? What is the engine speed when the popping is active? Does your logging indicate any ignition or fuel cut (overboost, rev-limit) -- usually the wideband will show lean spikes, but the result is often pops in the exhaust.

Another thought. Have you checked the timing with a timing light when this is active? Could you be getting crank trigger errors and loosing the timing?