ECU Difference

I have a 1990 Prelude Si ALB with a JDM B20A engine in it. (Engine is not the original, of course) My ECU is a PK3, which is the original ECU from the factory, and the car runs fine. I've noticed that most 89-91
Prelude Si's have a PK2. Does anyone know the difference between the two types?
Thanks!
Jon
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I owned a 90 Prelude SI,and there was a 2.0SI and a "SI";the difference was that the "SI" had 140 HP(that's the one I had),and the 2.0SI had 135HP,though both were 2 liter motors. I suspect most of those "Prelude SI" are the 2.0SI models,they were much more common. ISTR that the 140HP motor was an all-aluminum motor,no iron cylinder liners.
I don't recall the 90 SI as having anti-lock brakes,though.
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Jim Yanik
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Jim Yanik wrote:

What is the difference in the ECUs though? I mean, ALB (ABS) is computer-controlled, of course. So is it possible that the PK3 is just because of the anti-lock brakes, and otherwise, it's the same?
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BigJon wrote:

difference is probably the injection map. since "pk3" is sequentially higher than pk2, i'd stick with the one you have. otoh, around here, you can pick up ecu's from junk yards for ~$30. you could buy one and experiment if you /really/ need to prove it to yourself.
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Jim Yanik wrote:

I'm familiar with the engines: The 2.0Si had a B20A5, 135HP 1958cc, whereas the "Si" had a B21A1, 140HP 2056cc. The 1990-91 "Si" had two different "Special Edition" models: ALB and 4WS. Mine is the ALB. I can pop the hood and see the anti-lock brake module sitting behind the battery to the left of the distributor cap. Of course, I've also put it to the test once. The ALB kept me from having a nasty accident... I originally had the B21A1 in my car; but as I mentioned, I replaced it with a JDM B20A due to extreme oil comsumption.
You are correct that there were far more 2.0Si's manufactured. The 1990-91 ALB and 4WS models are hard to find... I felt lucky when I found this one...that is until I realized how much oil the B21A1 drank.
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Mine only had 20K miles on it when two hailstorms trashed it;it was never the same after the body shop was done with it;horrible cowl shake at

brakes I can recall for Hondas.

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