fuel problem need help

[13bboy]

when i baught my fc it had a hks programed fuel system computer [piggyback] aswell as the stock computer but i didnt realise the hks wasent pluged in,the harness was installed tho. I had 2 get the engine rebuilt for other reasons but the mechanic could not tune the rebuilt engine with just the stock computer could this b because the stock computer has been remaped or something to suit the hks computer

[91GSL-SE]

Ars you refering to the F-CON? you should be able to use it as a piggyback with your stock ECU. The stock computer should not need to be remapped with this piggyback system. IIRC the F-CON uses a different 3 bar map sensor than the stock unit.
Could you be more specific on what your mechanic is not able to tune?

[13bboy]

sorry, fuel and air mixture im pretty sure!!, and ur correct [F-CON]