Couldn't find it in the search...
I have been told that the 90-91 PM6 ECUs had slightly better programming than the 88-89s. They're all PM6s but I am wondering what the revision numbers are on each. The one I have is a
37820-PM6-L031. The guy I bought it from said it was out of a 91 CRX, but the data stamped on the side is 87.10.01 (October 1st 1987...)
help?

 

if it says 87 I doubt it will be a 90-91

SOME ecus say "89" but came in 90-91 civic si crx si

here is the code from a 91 crx si

37820-pm6-coo

But the only way to tell for sure is to open the cover and look for the 28pin prom chip. As only 90-91 si ecu's can be chipped 89's didn't have the 28pin chip.Its located in the bottom right corner (looking at the ecu with serial # on bottom)

Just for your info on the dyno it didn't matter as all the 89-91 ecu's I tried made the same #'s.

If you want better maps go with the 89 teg ecu...or get the si ecu chipped.

 

just popped the top off, and there is a 28-pin NEC chip in the bottom right corner. It is NOT socketed though... it is labelled IC4. Is that what you are taling about?
thanks

 

let me break out the crayons

 

thanks. Nice crayons. So I don't have the right year. I do want the option to chip it in the future, since that is allowed in IT by the SCCA these days. Hard to tell from an Ebay picture though.
thanks again.