Code itself does nothing. ECU just stores codes, but works according to real-time sensor inputs...
Is your AFR meter a wideband unit? Otherwise it won't be much help. If you completely remove TCU, you must figure another way to control electric cooling fan, because TCU controls it. For example, you could go with an in-line bimetal switch in lower radiator hose and a couple of relays, there is a thread on it somewhere here.
B230FT ecu from a LH2.4 B230FT will fit straight onto a B204FT ecu connector, but wiring is different. B204FT has EGTC, radiator temperature sensor, 6-pin TPS inputs, engine cooling fan wired to TCU, and boost solenoid output in the wiring loom, which is not the case with B230FT.
Is your AFR meter a wideband unit? Otherwise it won't be much help. If you completely remove TCU, you must figure another way to control electric cooling fan, because TCU controls it. For example, you could go with an in-line bimetal switch in lower radiator hose and a couple of relays, there is a thread on it somewhere here.
B230FT ecu from a LH2.4 B230FT will fit straight onto a B204FT ecu connector, but wiring is different. B204FT has EGTC, radiator temperature sensor, 6-pin TPS inputs, engine cooling fan wired to TCU, and boost solenoid output in the wiring loom, which is not the case with B230FT.