OK... I've read it's under the carpet on the passenger's side. I pulled the carpet down and still didn't find it. Can someone draw me a map?!?

Don't know about the 89... but thats where it is on my 91.
Theres a silver metal sheild that covers it.

Thanks, but I'm pretty sure it's different on the '89.

On 86-89 Accords the ECU is located under the driver's seat, towards the back.