Lude Generation

So I've replaced a dead H22A8 with an H22A5, and so far so good, except I'm getting a knock sensor ecl. I have fitted a knock sensor. The car is using the h22a8 loom and ecu and otherwise seems to run OK.
I've tried to run it with an h22a5 ecu that I have but it won't start (I assume that's an immobiliser issue)
I was wondering, do you think the different compression ratio is triggering the knock sensor error? Or is it more likely a dead knock sensor?
Had anyone come across this before?

About the H22A5 ECU that won't start your engine , yes it is surely an immobilizer problem.

About the Knock sensor, i'm not sure, a bad sensor can trigger an error, about the compression ratio, even if different from the H22A8 , it won't be a problem i believe... ... but the camshaft noise are différents between the two engines , so it could possibly make a different noise and create an error...

First i would start with the Knock sensor directly, try to unscrew it from the engine and start the motor with the Knock sensor plugged to the wiring loom but solidely attached and grounded to the car (and not to the engine) and see if you still have the error...

Hope it will help you

A5 doesn't have a knock sensor so it won't be plugged in.

A5 ecu will be looking for a different key chip.

@hondaddict thanks I'll give that a go. Maybe there is a reason why it doesn't normally have a knock sensor. I was thinking about running the knock sensor out of the engine originally, but the h22a5 had the hole and thread for it so I just screwed it in.
I'll report back in a few days.

As for the ecu I was hoping that it just needed the immobiliser to match the key and not the ecu, but I guess it needs all three.

The simplest answer would be bad knock sensor. Everything else should work fine together.

A new knock sensor did the trick. Thanks people.

It is a good new, i'm happy for you