Diagnostic computer port??
First - not all of the Swifts had a functional diagnostic port, a number of them had a 12 pin ALDL port under the steering wheel, and there was no connection to the ECU - but - even if the donor your engine came from had such a port (working or not), who knows if it made it into the new harness?
A 94 Swift would have had a connector under the hood into which a paperclip could be inserted and that would make the check engine light flash a failure codes - again - who knows if it made into the new harness?
A good place to start would be - what ECU are you running in this swap - do you have the original Swift ECU or an after-market one? Do you have an ECU at all (is it still EFI or carburetted)? Is there a check engine light, does it turn on when you turn the ignition on and go off after the engine starts?