I have an 1989 Civic, I bought it this way mind you. It's a B15B1 with a B2 head and an MPFI manifold off of something newer, not sure exactly what. Someone had put another harness in the car, presumably because of the swap and there are at least 10 connectors that go no where.


Here's the problem: The car idles fine, it hunts a little when it's cold but smooths out after a little warm up time. When you rev it up quickly it goes just fine but when you pull the throttle just off idle it cuts in and out violently as if you were turning the key on and off, it does this from just off closed throttle to about one quarter throttle. above that it will rev up and sounds fine. It does this in the driveway and going down the road, it jerks violently. (No fun at all) So I tested the TPS, it's perfect, the MAP is perfect, the ECT is again perfect. So while there is a bunch of connectors not going to anything the important stuff seems to be hooked up and working. It has perfect spark (The distributer looks to be brand new and somebody put a clear cap on it so you can see spark there) I replaced the plugs just for good measure but no help there. So just to ensure the wiring wasn't all messed up from the harness swap I checked the voltage at the ECU it was good too, I decided to look up the ECU part number, it is 37820-P0A-A51 which I looked up and said it was for a 94-95 Accord EX OBD-1, with an f22 V-tec/Auto. So obviously this isn't a D-series ECU. Now the car does idle and rev. So I'm kind of assuming this is THE problem, but I would have assumed that the car wouldn't even have ran but I'm no Honda expert by any means. I'm sure that the car should have a more correct ECU but I wanted some expert opinions on this before I jumped and replaced it. So If anyone has any idea on this I would greatly appreciate it. If there are any other potential causes of this problem I am open to ANY suggestion.


Thank you very much for all your time!

 

Yes you should def get the right ECU. They obviously converted the car to OBD1 to run that ECU, so the extra connectors might go to OBD1 sensors that you dont have. Although in order for it to ever run properly, you would need to fix/add those sensors (changing the ECU to a OBD1 ECU from a D series might fix part of the problem, but it depends on what sensors are missing). I don't know much about OBD0 Cars so I don't know what sensors it had or didnt have.

 

Well I found I guy on craigslist with a DX/MT ECU so I went and picked it up, I plugged it in and it seemed to work for the most part, the hunting idle is still there while the engine is cold though...