Hey everyone, figured I'd write up some of my observations from a little bit of testing I did today.

Hopefully it helps someone in the future and clears some questions that came up for me.

I currently have a obd0 b16a swapped crx, but have had a faulty ignition control module. I ordered a new one, but figured I'd test the old ICM from my d15 motor, just in case.

I have read on other threads that obd0 ICMs are NOT compatible across series. Aka, b series icm will not work in a d series distributor. (But obd1 and 2 are interchangable across engine series?)

When I put my d series icm in my b series distributor, the car still started just fine. No idle issues, no codes. After letting the car warm up, I rev'd it a little and found that the rev limiter with the different ICM had changed down to 7000 or so.

I'm really curious as to why the rev limiter changed, does anyone know why this would be? What exactly changes between different series obd0 ICMs?
And why are obd1 ICMs interchangable compared to obd0?

Lastly, if you're in a pinch, turns out that you can make a car run with no codes on the wrong obd0 icm—despite what people will tell you on others threads. I'm guessing it's not good for your engine, but might save you if you don't have a replacement ICM immediately on hand.
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David