It would be very unfortunate if you've finished your entire K-Swap, want to start up your car for the first time and ...
... you just hear the failing try of the starter to crank and start the engine up.
If you didn't spend any thought about the immobilizer it's very likely that this little chip doesn't want that you steal your ... ugh ... own car. The most immobilizer units prevent the fuel injection and interrupt the starter's circuit if they recognize any problem with the ignition key or ignition lock assembly while starting the car.
Because you exchanged the previous installed engine control unit with a K-Series one, the immobilizer unit of it doesn't "know" the ignition key of your car. There are a few options to solve this issue:
#1 Immobilizer Bypass
Let's start with the easiest solution. K-Tuned offers an all-in-one immobilizer and multiplexer bypass solution. The installation is very easy since it's done by wiring in the four wires of this little box into the ECU's harness. By using this bypass you're able to start your engine but the green immobilizer warning light in your dash will blink all time.
This is an easy option but the bypass will cost a few bucks. And, of course, your immobilizer and multiplexer system will be disabled all time. In some cases not praticable.
#2 Reflash Immobilizer
The cleanest solution. Honda dealers are able to reflash the immobilizer chip by connecting a Honda PGM Tester to the car. After the reflash process has finished, you'll be able to start the car with your ignition key, the warning light will turn off and the immobilizer system will remain active.
The only problem would be carrying the car to the dealer.
#3 Using An Aftermarket ECU
If you plan to use an aftermarket ECU instead of the stock K-Series one, you can sit back and relax in comfort. The immobilizer unit is soldered onto the platine of stock engine control units and aftermarket parts don't have one. If you use an aftermarket part in addition to the original ECU like Hondata K-Pro, you're able to disable the immobilizer from its configuration section.