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Wikipedia notes D14A3 as OBD2-a and D14A4 as OBD2-b.

Is this correct? And if so, does this make any difference to what options you got when it comes to harness swaps, compatible ECU's, required wiring, compatible dizzys and so on?

It's incorrect for D14A4. Both the P3X and P3Y ECU's are OBD2a and look almost identical. Performance (given similar mechanics) is also close to identical.

It's the D14Z1/Z2 engines that are OBD2b.

and do we know the practical differences between obd2a and b versions?

saxophonias wrote:and do we know the practical differences between obd2a and b versions?

I think all obd2b have crankshaft sensors in contrast few obd2a cars have crankshaft sensors.
Also all obd2b have 2 oxygen sensors.
I think obd2b cars are more environmental "friendly" than obd2a cars with ecu maps, fuel efficiency etc.

I have noticed that when my car have extra load pulls better at the same road in some situations, like hills with 5th gear.
I think it is due to the ecu. Ecu might takes signal that the car has extra load from the sensors (MAP and TPS) and running different maps.
What is your opinion it is possible? Or it is my idea?

*I have to add that in some hills when cruising I have to lower the gear from 5th to 4th to maintain the cruising speed. But when I have some extra load (2-3 extra persons) this not happens.

** Not to misunderstand , this happens when I want to keep a cruising speed and not when I want to go fast.

I think in mine happens just the opposite as it gets heavier.

I thought we decided a while ago that it was the 96-98 EJ9's that were OBD2a and 98+ that were OBD2b??

CIVIC EJ9 96-98 = OBD2a

CIVIC EJ9 99-00 = OBD2b