You will not damage the B16 engine by running the P72 ECU, however it will run rich. This will eventually damage the catalytic converter (if equipped) and my gum-up your exhaust ports. The P30 ECU 'should' run much better on your engine than the P72 ECU. If there are other upgrades on the engine (ie: intake, header, etc), then the difference may be due to the B16 running too lean with these mods and not being tuned.