97 civic hx ecu vs 98 ecu?
 

does anyone know what the differences are on the each ecus? they both have different part number is there any real difference?

according to my honda service maual, there are 8 sytems in the 96-00 hx. 96-97, 98, 99-00, manual or auto, and cvcs thrown in for a couple extra variants. each one looks for different sensors. most of system is the same, but there are differences between the three that will matter. how much will it matter, and can you add a component to fix it? oyi vey.

I ended up with 98 ecu, 2000 intake manifold, and a 96 wiring harness and it was a PITA to get everything working right. like a month of full time work. stick to the right part number for your application IMO. unless you want to stupid, like me.

i did not but this wonderful manual until i was almost done. go figure. if i had, i would have followed my advice.

just came back from a drive with the 97 ecu. works fine without any problems. i have no idea what the difference is but it works. regardless the vendor that sent me the wrong part is sending another one. i've made some notes on how this ecu reacts i'll compare with the 98 ecu and will post any new findings.

it could very well be fine, and run the car just fine, but if you run it for a few days and turn if off and on a few times you might see a couple check engine codes. I should clarify: my car ran fine from the get go, the issue was CELs: and getting a car smoged in oregon now requires that you are showing no cels and the ecu must be "ready". it needs to have been driven long enough for the CELS to pop up. if you reset the ecu and drive to the smog station you fail "not ready" (i know, i tried). I figured i would brain dump on this i case someone researches hx/y5 stuff.

so far no cel. scan gauge tells me the ecu is "ready" for anything. this ecu will be in the car for 2 more days until i have to take it out and send it back. few things i've noticed with the federal ecu ignition timing is more advanced when cruising and it stays in lean burn even when you are firm on the gas pedal.

interesting stuff, no cels is always good news! damn i wish that happened to me more often. do you have good bead on what rpm lean mode can stay engaged to? i think i feel it up to 3400-3500 in my but dyno in light acceleration

the "ready" "not ready" terminology was printed on my failed report from the DEQ (DMV in oregon). My $100 code reader would not show it. The car needs to have been driven some number of miles before the system creates enough data to move status into the "ready".

scangauge shows the ready not ready for the ecu. i was surprised it was ready with 1 short drive. the stock CA ecu took a few days before it was "ready" not that i was taking it for a smog but a bit odd.

im not sure how high of a rpm it stays in lean burn but i've gone up to 70mpg and still in lean burn. i'll try out and see if i can go any faster and stay in lean burn.

i did noticed it goes out of lean burn when slowed to around 47mph in 5th gear.