Hi everyone! My 1994 Honda Accord LX was acting up for a long time and then finally stopped starting. The check engine light when I tried to start the car would stay on and it would refuse to turn over. It would start right up if that check engine light went off, and no check engine light would be on during driving it.
Much frustration later, it was the ECU. We pulled the ECU and replaced it with one from pick and pull, as we just needed to make sure that was the problem before we bought a new one. So, here is my question. The ECU that came from my car was a POB-A51. The ECU in it right now is a POA, and though I don't know the last digits I do know it was pulled from an automatic and not a manual.
The car starts right up now, but the check engine light stays on now, is that because I have the wrong ECU? Should I definitely not drive it until I have a POB ECU like it had before?
The POA ECU is for a Vtec engine if I understand right, which mine is not.

 

Read the code but I suspect it's not getting a signal from the vtec equipment.

 

The P0B is for the 94-97 Accord's with the F22B2 non-VTEC motors (130hp/139tq.). The P0A is for the 94-97 Accord's with the VTEC F22B1 motors (145hp/147tq.)

The two ECU's are very similar but not exactly the same. The F22B1 makes 15 more hp and 8 more tq due to the VTEC system.
The P0A is going to be looking for a VTEC oil pressure sensor input and has a VTEC solenoid output, that is most likely why your F22B motor is causing the Check Engine Light.
Essentially the engines run different ignition timing and fuel delivery maps because of the VTEC system and the different power outputs.
What I don't know is if the P0A ecu is going to run the correct fuel and ignition maps for the F22B2.
When a P0A ecu does not detect a VTEC oil pressure sensor and throws a code, It is possible that the P0A can run a non-VTEC "mode" that would change the mapping to essentially that of a P0B ecu.
It is also possible however that a P0A is completely incapable of operating a F22B2 motor properly with the correct fuel and ignition tables. (I'm not sure of what exactly the ecu can sense and compensate for)
How does the car drive? Does it have normal power output throughout the rpm range?

If you don't want a check engine light illuminated, have determined the ECU was the problem by getting it to run on another used P0A ecu, then I would just find a P0B ecu for the car (Make sure it is from an automatic, if thats what your car is). eBay is a good place to look, you can find a used P0B for right around $50

 

If you have a SOHC Non VTEC 2.2L Accord you NEED the P0B ECU.