Hey guys and gals. I could use a little help identifying an engine/ECU pairing. The car I purchased is a 1998 base, per the vin, but after have a few small issues with the car, I think a different engine may be in it. The engine is stamped "H22A" and below that is "3000145". Am I correct in assuming it's a 99? Jdm? U.S.? Anyways, before seeing that, we installed a 98 ECU, and have had a constant misfire code, regardless of it not misfiring.

Just need help with finding the correct ECU. Or, maybe the one I have is ok.. I don't have the part number on hand, but it was pulled straight from a 98 base.

US engine is H22A4. JDM is H22A.

Why did you change out the ecu?
That answer could possibly help us help you better.

A bit of history;
Honda calls it ecm. But most call it ecu. So if somebody says ecm it's the same item. Engine Control Module. They also call what most call a CEL a MIL. Manlfunction Indicator Lamp, which is actually correct. In the old days a CEL meant you were low on oil, overheating or something was about to cause your engine to fail. Blame Ford for CEL lights for everything included.

Download a service manual from the diy section and scope out chapter 11 (fuel and emmisions). There in that chapter is what possibilities occur to cause a misfire code.

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God's Not Dead

Ah yes.. The car had an ECU from a 92 civic in it, when I purchased it. It wasn't running good at all, and my mechanic discovered the civic ecu. I purchased the 98 base computer simply going by the vin number... Obviously assuming the same engine was in the car. The previous owner wouldn't return my call after finding out the engine has been replaced. We put the 98 computer in and it runs fairly well, minus the cel and running rich. I just want to narrow it down a bit, and I'm leaning towards the fact that I simply just need to get the right ecu/ecm :P

Sorry for the poor message details. I'm at work... D:

One thing to consider is the fact that there are 2 directions the previous owner could of went. An obd1 h22a which a lot of people convert to obd1 for tuning purposes
Or stayed obd2 h22a
The standard ecu for the jdm h22a obd1 is the p13. I am unsure of the obd2 because I never owned a obd2 prelude.... But I would assume there would be a difference...

Just something to think about while trying to find the correct ecu for your setup.

Oh also be aware of the fact the engine is jdm. Not usdm, that could also make a difference in setup

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That answer helped a lot.

Running rich could be your 02 sensor is wearing out but not enough to throw a code yet. Could egr system is filling up with gunk. Don't blame the ecu just yet.

Does your distributor have the 'coil' on the outside? Others know more about the jdm motors to us cars than I do. But I do know that when you take a few parts (like your distributor) from the A4 engine and put it on the A engine that helps it 'speak obd2' to your ecu.

Do you still have the offending ecu? It should have a 'p' number like 95 mentioned. But if you put a civic ecu in a prelude it has to be tuned to speak Prelude.
Most cats these days with a few tools swap out parts with no idea how to and when it runs like crap they pawn it off on somebody else.

Like I said, check out the manual for misfire code causes. And check your dizzy cap n rotor as well as plugs n wires to make sure they are tip top.

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God's Not Dead

The distributor is internal coil. First thing I replaced (it actually was worn out and cracked), was the cap, and rotor. That's obviously when I realized (after learning a bit more about th stock prelude) something was off. A 98 base should have an external, and here I am with internal. Plugs and wires are ok, for now. I'm assuming running rich like this could eventually cause harm to the plugs? I do not still have the civic ecu.

37820-p28-a01 was the ecu that was in the car.