Written in marker on the lid is "Honda 2001 S2000 ECU (AP1)".. great.

But the Part number on the box is "37820-PCX-A02"

Searching threads this says it's an 02+ ECU. Searching online catalogs, it shows A02's for 00, 01 and 02's.

The car I have is an 01, but with EMS, this was an "extra". Anyhow I may part the car out and I need to figure out if I have an actual 00-01 ECU so I can use it with my AP2 motor "safely" (guess the 00-01 runs a bit richer).

Anyone know any other way to determining which ECU this is? Part # on the components inside? Something etched on the PCB? Anything?

 

Honda regularly updates parts and the last digit is how they normally do it. So if you were to try and order the part you would get e newer part. So the ap1 made in late of 01 may have already been updated to the 02 part. Make sense?

 

The part number should be on the label on the side of the ECU

 

you have an 02-03 ecu

 

That's somewhat conflicting.

Would it be safe to say that it's entirely possible I have a "2001" AP1 ECU but that because the part number is A02 I have the leaner fuel maps and therefore I should probably source an A01 to run a F22 off it?

 

There is nothing conflicting about it at all. You have an ECU from an AP1. End of story. Based on the part number it is considered an AP1 002-03 stock unit. For 00-01 it would be a replacement part. You are correct, the fuel trim would be differant, and less rich as reported by the early owners.

Sure would have been nice if this thread was about what you really wanted to know, running an F22C using an F20C ECU. Run it.

If you are going to go through all the trouble of swapping the ECU, get an 04 ECU and run the F22C with the proper ECU.

 

I appreciate your help, but that response is not entirely fair. I wasn't asking if it's okay to run an AP1 ECU with my motor because I already know that answer. I'm asking if there's a sure-fire way to identify the ECU outside of the sticker on it because I have reason to believe it's not what the sticker suggests.

Obviously with what was written on the ECU I have ("2001"), along with the fact I have an 01 Model car it seemed less likely the ecu I have is a 'replacement' and just in fact the original that came with the car. To complicate things more the original owner said he didn't remember where the ECU was fron, but that he thought it would be an AP2 ecu acquired along with the motor. Hah! Your original post suggested that Honda could have made a mid model year replacement/upgrade and therefore A02 COULD be original equipment from an 01. But for all I know, I have the shell from an A02 and the guts from something else, based on what was written on it.

Anyhow, if that's true, it seems it would be more accurate to say the safer AP1 ECU for running an F22C would be the A01 part number and not to reference the model year.

As for your suggestion of going with the 04, if I do in fact have the leaner ECU, then yes, it looks like I should go through the trouble of finding another ECU. However it's my understanding from other posts on the board, an AP2 ECU is going to require some rewiring efforts as it relates to interfacing with the AP1 Cluster. Which, if true, and I have no reason to doubt it, is a whole other 'trouble', but yeah if I have to go through this, it's probably the preferred hassle than hoping I don't accidentally overrev a car I autox on a regular basis.

On the flip side it could be just as easy to swap out my A02 (some suggest it's more powerful) for some 00-01 owners with and A01 ECU), course, for my situation it would be nice to identify the ECU by the PCB rather than a sticker on the case. I wouldn't want to sell someone the wrong thing, or sell something I didn't have to sell in the first place.

Anyhow again, thank you for your assistance.

 

We all know that some changes were made mid model year. I was subjecting that could also be the case with the ECU in question. For example, they changed the oil jet bolts mid 2002. They changed the center console and a few other bits to support the hardtop mid 00. There are others too I am sure of it. In some cases they change the part design and incorporate it in all cars going forward from that date, the spare part number get a new suffix as a result and they phase the old part number out of their system.

In the case of the ECUs, besides the external part number, there is surely a ROM number of the chip with the programing. I am sure the core PCB are the same, just a slightly different software load. That has not been something that has been investigated publiclly to date that I know of.

 

Yeah that's entirely possible that the ROM is a static part number across the years.

I guess the only safe thing to do here is get an A01 or rewite the cluster with an AP2 ECU.

Thanks.