h23 ecu problem - Honda Prelude Forum

lude203 · 02-06-2010, 08:21 PM

ok, i bought a JDM h23a NON VTEC motor from hmotorsonline.com a while back and had it swapped into my 1993 prelude si....
heres a link:
http://www.hmotorsonline.com/shop/sc...age&item=30030

i have 2 ecus: 1 is from a 1992 prelude and the other one is from the 1993

the 1993 ecu makes the car shudder at take off and it missfires but runs like it should when the accelerator is pushed more!

the 1992 ecu runs sluggishly and makes my gas mileage horrible

(air/fuel ratio problem???)

i checked everything mechanically and do tune ups when needed and cant find anything wrong with it mechanically to my knowledge.

i did a little research and found out the motor may have come out of a "Honda Ascot Innova" - according to wikipedia
heres the link to that : Honda H engine - Wikipedia, the free encyclopedia

so can anyone tell me what ecu im supposed to be running with this motor, or maybe a ecu that might make it not misfire and shudder at take off???

PS:

i was reading this forum post about injectors and it says that the jdm h22a and h23 both run on a p13 and (h22 ecu right?) but i dont know if its referring to the blue top vtec h23 or my non vtec h23?

please help me im going nuts and i need this car fixed asap! any help is appreciated!

TruNinja619 · 02-07-2010, 12:02 AM

I bought the same longblock from hmotorsonline (it was an H23A3 motor actually) and I used the same ECU that I was using with the H23A1 motor that's in my 93 Si.

I know its a long shot, but when I remember doing the swap, the vacuum ports on the H23A3 intake manifold I used were different than if you used the H23A1 intake manifold. Probably recheck the vacuum lines that are EGR related.

lude203 · 02-07-2010, 02:01 PM

UPDATE: while the 1992 ecu ( i was running it on this ecu for a while because it seemed to work better) was plugged in i tried messing with the distributor to adjust the timing and it was a complete faliure and made the car ping,misfire,CEL,and stall even worse than before....

now i plugged in the 1993 ecu and theres no CEL and no misfiring or anything now!! i think the timing was retarding because the distributor was not set right or something...idk.....but ill keep driving it around and see how it goes....

i checked those vacuum lines to...theres one line thats capped off that comes off the top of the throttle body but i dont know what it does...ill take a picture and post it up or maybe take a video

lude203 · 02-13-2010, 10:13 PM

ok nevermind that last post....the konck sensor CEL came on and now it runs slow just like before.....

i did a little more research and found a post about someone that did this JDM h23a swap in an accord or something....said he used a p75 ecu which is the integra ls non vtec ecu...said it bypasses aib,knock sensor and something else.... so does anyone know if this ecu could make the car run better by bypassing all this stuff?

lude203 · 02-13-2010, 10:34 PM

another question.....according to ECU - Honda Prelude Wiki

the correct ecu for this motor is the p51-900 (JDM h23a honda ascot innova ecu) but i can only find this ecu in AUTOMATIC!! my swap is the h23a motor with the 1993 prelude tranny ... i would keep looking for the right ecu for this but im planning on turboing this car so i can just get a hondata ecu and get it tuned right?

Artifex · 02-14-2010, 12:19 AM

You should be able to run the motor just fine with a p12 ECU, which is the USDM h23 one.

lude203 · 02-14-2010, 07:47 AM

isnt the p12 the sohc f22 ecu?....anyway the h23a1 ecu is the p14 and thats what im using...i actually have 2 of them...a 1992 p14 ecu and a 1993 p14 ecu

TruNinja619 · 02-14-2010, 01:34 PM

honestly, using your P14 ECU should be fine. Especially when you're using the same motor, the ECU would be the last thing I would touch. People use the P75 ECU if they're planning on using hondata to tune their H23 motor.

For you knock sensor code, most likely you need to replace it. As for your knock sensor, if I remember correctly, those motors (JDM and EDM) didn't come w/ one and you have to install the one on your USDM H23 block. its either that or you just have a bad knock sensor.

Artifex · 02-14-2010, 06:42 PM

Quote:

Originally Posted by lude203

isnt the p12 the sohc f22 ecu?....anyway the h23a1 ecu is the p14 and thats what im using...i actually have 2 of them...a 1992 p14 ecu and a 1993 p14 ecu

Yeah you are right, p14 is what I'm thinking of. That should work.

lude203 · 02-16-2010, 06:56 PM

ok i think i got it now.. my knock sensor is brand new...i replaced it a couple of months ago when this lude was my DD so i know its not that.... i plugged in the 1992 ecu and had that annoying delay and almost stall thing going on when i tried to accelerate(kind of feels like the car stops "breathing for a quick 2 seconds and then shoots up to where its supposed to be")... i took a closer look at that odd capped off vac hose that was on my throttle body that only comes on the JDM version of this motor...i think its apart of the JDM emissions setup or something...i noticed something was odd about it...like the nipple piece was crooked...i simply touched the vac line and the whole thing SNAPPED OFF....the motor started to rev a little higher and then i gave the motor a quick rev and it seems to be working fine from what i can tell....i did not have too much time to test it but ill report back with details just in case someone else has this stupid problem in the future because its VERY ANNOYING!

im going to try and get my old throttle body from my old motor if they still have it at the shop where the swap was done

lude203 · 02-18-2010, 07:56 PM

yup.....i bled the coolant lines.....accidentally broke off that jdm only vac line on the throttle body, put in the 1992 ecu, and messed with the ignition timing and walla!! car runs better than ever before! no more studdering..shakes...fluctuating idles...nothin...just smooth as can be

lude203 · 09-02-2010, 09:31 PM

hey just if anyone ever reads this again.... i am an idiot.... back a couple of months ago i didnt really didnt know to much about cars... my problem turned out to be that the people that did the swap broke the wire that goes to my knock sensor, when they tried to "fix it" they took the wire out of the clip that goes into the knock sensor and taped up the wire and then when they were going to insert the wire back into the clip they put it in the wrong slot (on the clip there's 2 slots and the knock sensors a 1 wire system) so long story short my knock sensor was "plugged in" but was never making contact hence the retarding and misfiring of the motor. i still dont know why till this day that 2 of the same ecu's would make the same car act differently and throw 2 different codes but i think ive come to the conclusion that one of them is broken or something.........but yeah im stupid and disregard this post if your looking for an actual solution to the problem explained as it had nothing to do with the ecu in the end..........