i have an 89 hf and i got an 91 si engine that i am swaping in...the engine came with the si ecu and i was wondering where the ecu on the hf is located so i can swap them....

 

it should be on the passenger side floor under the dash - where the floor slants up towards the firewall area - move the carpet to the side and you should see a metal cover - undo the four bolts holding it down and you should see the ecu.