Atrevido

I own a Prelude 2.3 Si '92, and now in process of swap. For swap - JDM H23 VTEC engine from Accord SiR 1999. I got the ECU from the Accord, but I guess it's a wrong one. The full text printed on the ECU box reads:
2H
37820-PCF-N51
CY-EH2955A
NO, 11250 -1
Matsushita Co.

Questions:
1. Is it possible to use OBD1 P13 ECU with OBD2 engine H23 VTEC?
2. Is it possible to use OBD1 P14 ECU (my old one, non-VTEC) with OBD2 engine H23 VTEC? (I understand that VTEC will not work, but will the engine run at all?)
3. What is the code of my new ECU from Accord, is it CF?

Please help! SOS!

reckedracing

you can use a p13, but need to convert the motors electronics over to obd1 to match the ecu, i think distributor and possibly injectors are all that would need to be changed but not positive...

yes, your motor should run with the p14 minus vtec, but you would need to convert the motors elec's over to obd1...

check into a obd1 to obd2 converter, this might let you use the new ecu you got with the motor...

post pics of the motor please, i have never seen a h23vtec in real life, whats the block stamped as just h23? or h23a? or what?


this is a difficult topic cause not many people in the US, and i think no one on this board, have dealt with the h23 vtec...
why did you get this instead of just an h22? aren't they the same power ratings?

Atrevido

The engine valve cover is dark blue color. The letters are H23A.

I don't have OBD2 distributer for my new engine (it was broken during transportation). I have my old OBD1 distributer from my non-VTEC H23A1 engine. Does it mean that I'll not be able to run the engine if I use OBD2 ECU?

By the way, I want to use all my old harnesses OBD1. Since the japanese ones are too short (for right-side driving wheel). Is it OK?

Atrevido

[quote]3. What is the code of my new ECU from Accord, is it CF?

Does anyone know it? What engine the "CF" ECU corresponds to?

formby

as far as i know you can use the OBD1 harness on the motor...use the injectors/dizzy/ecu from the old motor..you might have to modify the dizzy.....and use an rpm activator or a vafc controller for the vtec...you might also need to run wires for the knock sensor......good luck post some pics....also call hasport....www.hasport.com they should help you with wiring products

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Atrevido

Thanks!
And what will I get in this case? A VTEC motor? Will it have all 200HP, or less?

reckedracing

a properly tuned vafc should give you the full 200 horse

formby

Thanks!
And what will I get in this case? A VTEC motor? Will it have all 200HP, or less?
[/b][/quote]

what i meant was....use the harness from the motor already in the car on the h23 vtec engine....its already a vtec motor ...just use the vafc to activate the vtec

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Atrevido

I was told that if I use P13 ECU with my new motor, it would not run perfectly as the fuel and timing maps will not be ideal because of the slight differences in the engines H22 and H23. Is that correct?

reckedracing

there is very little diffrence between the two motors so i think it will be ok...

only way to know for sure is to view the fuel maps for both

i think they both have 325cc flow injectors...

formby

bro who is telling you this...and how do they know?

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reckedracing

no one is telling me this...

i've been searching for info on this god damn motor all day and haven't gotten dick for information...

it has the exact same power ratings as an H22 so i think they just got the displacement up over 2250 so they could call it an H23, i think the h22 has displacement of about 2156....

formby

not you man...the original poster....who is telling him it wont work...lol

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tab

I agree with you guys, I'd do a standard OBD2>1 conversion to the engine, use the stock harness. However, I think I'd run the VTEC wires and use a P13 until I could have it properly tuned. There have been a lot of people on here in the past using RPM switches and complaining, and a few that were happy, go figure.

Either way will work.

__________________
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2003 Chevy Avalanche
Leather, Moonroof, Z71, tow package, bose+six disc, nice.

1992 Accord EX (sold to good friends)
JDM H22A
H22A Auto Tranny w/LSD
I/H/E -- All stainless w/2.5 inch Catback

1968 Oldsmobile Toronado
Project car, 455 ci front wheel drive, nasty.

Atrevido

They didnt tell me it would not work, they told me that it would not work perfectly. The reason, - different fuel and timing maps.

reckedracing

use the stock p13 until you can get it tuned by a professional...

Atrevido

Here are some charecteristics of H23 and H22 engines for comparison:

Model---------------------------------Accord 2.3 VTEC SiR-----------Prelude 2.3 Si----------Prelude 2.2 VTEC
Doors---------------------------------5D-------------------------------2D-----------------------2D
Year----------------------------------1999-2000----------------------1992-1996---------------1993-1996
Body---------------------------------GH-CH9-------------------------BB2----------------------BB1
Engine code-------------------------H23A (for Japan)---------------H23A2 (for Europe)----H22A2 (for Europe)
Displacement (cm3)-----------------2258-----------------------------2259-------------------2157
Bore x Stroque (mm)---------------87 x 95--------------------------87 x 95----------------87 x 90.7
Compression ratio-------------------10.6:1---------------------------9.8:1-------------------10.0:1
Valve gear ---------------------------VTEC DOHC 16v----------------DOHC 16v------------VTEC DOHC 16v
Maximum power---------------------200PS/147.10kW/6800rpm----160PS/118kW at 5.800rpm---185PS/136kW at 6.800rpm
Maximum torque---------------------22.5kg-m@5300----------------21.3kg-m@4500rpm----21.2kg-m@5300rpm
----------------------------------------220.65Nm(at5300/min)--------209Nm(at4.500/min)----212Nm(at5.300/min)
Power density-------------------------7.15/7.2-------------------------?-------------------------?
Redline (rpm)-------------------------7200-----------------------------6300-------------------7500
Fuel (90/120/city/mix) l/100km-----8.7-------------------------------6.8/8.6/11.0/8.8------6.9/8.6/10.9/8.8
0-100km/h (0-62m/h)----------------?---------------------------------7.7 sec-----------------7.1 sec
Max. speed-----------------------------?----------------------------------217 km/h-------------228 km/h

Atrevido

Before I get a P13 ECU I want to temporarily use my P14 ECU. Without any VTEC connected.
In this case, theoretically will I have 160HP or less/more? As far as I understand, since the compression ratio is higher at the new engine, - it should be more productive (or there's nothing to do with the comp. ratio). Is that correct?

reckedracing

it has to do with the comp ratio, but the h23vtec head design is made for the low rpm rockers and then the 3rd vtec lobe...

i would assume you should be approx around 160

my friend had an h23 in his accord, swapped to h22, but ran it on the h23 ecu until he got the p13 and i THINK it didn;t pull quite as hard... but it was a close match, but the h23 had 160K miles and the H22 had less than 20K so...

who knows..

Atrevido

So, your friend ran VTEC engine H22 with non-VTEC ECU (P14 I assume)? How did the engine work? Did he make any additional changes when running with non-VTEC ECU, like distributor, injectors etc.?

reckedracing

the engine worked ok, but its a slow pig compared to when the vtec is hooked up..


i do not know all the specifics on the electronics, i think he could not use the h23 dist cause it was diffrent but i'm not sure, i know he had to convert it over to OBD1 cause it was a 2001 motor...

i will ask him exactly what dist he used and what he changed, i will have a better answer for you on monday

Atrevido

I tried to finnish the swap on Sunday. That wasn't easy.
There are some unexpected (for me) differencies between 2 systems.

First, injection systems are different.

1. Idle Air Control Valve (IACV)
Injector of H23 non-VTEC engine
IACV has 2 wires and it's managed by vacuum

Injector of H23 VTEC engine
IACV has 3 wires and it's managed by electronics

2. There is no idling screw (not sure about the name) on new injector.

So, the injector system is completely different from ANY Prelude OBD1 & OBD2 (I thought it should be similar). It's most probably like Accord Type R.

3. EGR Control Solenoid Valves are different.
H23 non-VTEC engine
EGR has 3 wires and it's managed by vacuum

H23 VTEC engine
EGR has 4 wires and it's managed by electronics

In the beginning we thought to get a 2.2VTEC Accord Type R electroscheme (we had only OBD2 Prelude 2.2), that should coincide with H23 VTEC Accord SiR. Thus, we could check where those additional wires go to.

But then, we found a fresh solution.
We traded places:
- Injectors' heads (together with the IACV and idle screw). So we left the new injector and equipped it with the old injector's head.
- EGRs (though, OBD2 EGR inner wholes are smaller)
- Injector connectors. As I use OBD1 wires and OBD2 injectors, we cut off OBD2 connectors from my OBD2 harness and solderred them to OBD1 harness.

It was too late to finnish the swap, so we decided to continue another day.

Not sure how it's all gonna work... I'll keep you guys informed.

Atrevido

Do you have any info?

Atrevido

Since I'm looking for a new P13 ECU, I'm thinking of getting a chipped one.
What will be better for performance SKUNK2 RACE ECU or JUN ECU?

dohcvtec_accord