Hey guys I tried researching this but am not 100% sure. I have a 5spd 96 lude with the obd2 h23. Found out that I got a bent piston rod and a cracked camshaft so I'm thinking about just swapping it. I wanna do the blue top h23 obd2 but all I can find are ones with a auto ecu and most have a cut harness so my question is if I was to purchase the engine anyways would I be able to reuse my old harness for the blue top? Also would I have to find an ecu that's specific for the Blue top h23 or would a ecu from a post 97 obd2 h22 work since its programmed for vtec? Also if I was to fine one with a complete harness but a/t ecu would that fit with an ecu from a 5spd h22.

I haven't been able to drive my car for two months, it's driving me crazy. I'm gettin desperate and it's actually easier to find the blue top h23 than it is to find a obd2 h23

 

nvm i got it. just gunna use a chipped and tuned p28 ecu with a converter that will plug the obd1 ecu into the harness. still looking up the compatability for the engine harness tho. If my non-vtec harness will still work with the vtec since they are both obd2 and h23. if you have any insight please let me know.

 

Just plug in your harness to the motor. VTEC or NON VTEC does not make a difference on what shape the rest of the sensors plugs are. You will need to swap over your driver's side upper mount bracket. You will need a USDM oil pump with the crank trigger on it (not sure if this is true for OBD1 cars).

I ran my stock OBD2 H22 SH ECU for my swap. I swapped the bluetop into a 97 SH. The stock H22 ECU works just fine. I don't like pre chipped ECUs....and I didn't want to spend money for a tuneable one. I don't know the rev limit of a stock H23...so I was only revving it to about 7500RPM. The rev limiter on H22 ECUs is like 8100 or whatever. So use some self control.

You will have to make a sub harness for VTEC. Do H23 non VTEC engines come with a knock sensor? If not, you will have to make another sub harness for the knock sensor. Pin both sub harnesses back into the ECU.

Use your H23 intake manifold and all the sensors. You can also re-use your old working sensors on the new motor if needed.

 

You can get a aftermarket harness that will let you wire it up, my 4g had 1 plug for the spool valve circuit already next to the passenger shock tower, it's a green/yellow single wire plug. The other is for the oil pressure switch which you can have the ECU set to not look for but if you need it there's a ton of write ups on how to add the plug to your existing harness, that's what I did. I just took it from the RHD harness that came with the engine, found the empty slot on the big main plug where the wire went, put the pin for the light blue wire in then grounded the black wire.

Here is a pic that should help you out, even though it is rotated you should still be able to see how I inserted the blue wire into the harness where you'll have an empty slot. Taking the plug apart on the harness is pretty easy, just be careful not to break it, easiest if you have another harness so you can just take the pin and the plug so you don't have to do any cutting.

http://img844.imageshack.us/img844/4800/1003101122.jpg

 

for simplicity reasons here is a link to the actual engine i plan to purchase. it is a local pick up for me which is nice for $$ reasons and bc i will be able to physically check it out. i plan on going out there tomorrow to look at it and ask my questions so if you have any advice feel free to send it my way

http://www.ebay.com/itm/JDM-97-01-HO...ht_4256wt_1197


ill start by saying that im pretty new to ecu compatability and stuff. i know a lot about everything else but tend to get a little confused with all the sensors and everything bc there are so many lol. when you say i will have to make a sub harness for the vtec what exactly do u mean. a little lost there. I know the h23 does already have a knock sensor. now would this engine already have the oil pump? or no? and im assuming if i had to purchase one it would be a h22 oil pump? damn i feel like a noob right now, sorry for the questions. im a fast learner though.

 

JDM Engines dont have the crank trigger on the oil pump. I'm not sure if you need the crank trigger for an OBD1 internal coil setup. If you do need the crank trigger, then yes....order a USDM prelude H22 oil pump.

The ECU does not care what hunk of metal is under the hood. It just needs the right signals from the right sensors at the right time.

The wiring harness is a network for those signals to get from the sensors to the ECU.

The sensors from the H23 bluetop are the same as the sensors from your H23A1. So...nothing changes. The same sensors providing the same information. Besides that, you'll be re-using all the fuel management sensors from your H23A1 anyway since you're re-using your intake manifold.

Plug them into the wiring harness as you normally would. Use the H22 ECU (or a chipped ECU if you want, I guess).

Your car probably isnt wired up for VTEC. So youll need a 2 wire sub harness going from the right pins of a H22 ECU to the VTEC solenoid in the engine bay. Pin the ECU connectors at the right spot. Run those wires along the main harness into the engine bay and to the VTEC solenoid. That's a sub harness.

 

Ok cool got it. Now my guess is with this engine the harness is probably cut and it's from an a/t tranny anyways but im assuming that engine would normally have the sub harness already built in. If I happen to get lucky any that's intact would I just splice that off the original harness then pin it in with the new ecu? That makes the most sense to me.

 

Ok forget about the sub harness sorry for complicating everything. I just learned that rywire sells the sub harness for vtec. Ok with that out of the way and the oil pump is something that I'll prob need, I understand that. Now about the driver side upper mount is all that's left. What mount would I need to purchase to make it work. I just assumed since my previous block was h23 it would work but I can see how a jdm would be different.

 

Well...you dont splice anything. The original harness is JDM....which would put the ECU on the wrong side of the car.

You can use the old harness to harvest some plugs, wires, and pins. Thats about it. But there's no splicing. You pin 2 wires into the ecu connector. The other end of those 2 wires goes into the VTEC solenoid and oil switch plugs.

 

^this

x2

Leave your USDM H23 harness in the car, pull that hunk of metal, drop in the new hunk of metal. Run 2 wires for VTEC through the firewall to the proper pins on the OBD2 ECU plug.

ECU options
Swap to a 96 OBD2 P13, harder to find
Get the OBD2-OBD1 conversion harness and use either:
-OBD1 P13
-OBD1 chipped ECU with an H22 base map

 

Oh...shiznit. Didn't see you had a 96 (OBD2) lol. Yeah, you'll need the USDM oil pump. Or you'll need to wire everything into an internal coil setup. I've done both. Buying the $200 oil pump is worth it. I wouldn't re-use your old pump from your H23A1 because it might have been damaged when the engine blew...or might have been the cause of the engine's bearing failure in the first place.

Btw, I recommend that you mark all the harness plugs for which sensors they go to with a permanent marker before unplugging them. A lot of the sensors have the same plug type and same location vicinity.

Also...a tip: don't forget to unplug the power steering pressure switch before you pull the engine. Its a green/gray plug located under the intake manifold, on the power steering pressure line.

 

Well you need to replace the bracket. Im talking about the metal mount bracket that's bolted to the block....the one that's bolted up under the timing belt cover. Take the metal bracket off of your H23A1. Bolt that onto the bluetop. The bluetop is an accord engine...so the brackets are different. Keep your stock rubber/metal engine mount as well to bolt everything into the chassis.

 

Oooh ok I see so I just gotta swap that bracket from my engine to the new one. Cool thx.

About the two wires being pin I would have to pin the wire into the sensor and the other end into the ecu right? If so wouldn't I be better off buying the sub harness for 60$ and use that to replace the plug for the sensor to ecu instead of dealing with which wire goes where? Or would that not work?

 

Depends on whether you would rather spend money or do it yourself. Either way you have to get the wires through the firewall and connected to the ECU.

$60 harness vs $5 in wire and ECU pins. It's really not difficult, not $50 difficult, IMO.

I looked at that sub harness, its nice looking, but not necessary. If you've got a few feet of wire and some minor soldering skills, all you need to buy is ECU pins.

 

Ok that's what I needed to hear. Basically either way will work its just about how much to spend on it. Thank you so much to you and everybody else who contributed to this topic even if I didn't "quote" you your input was helpful. I will be purchasing the engine today to begin the swap

 

Don't even need to buy pins if the engine comes with a harness, I just unpinned the connectors I needed and added them to my harness, free.

 

I go to junkyards and cut off a ton of ECU connectors. That way I have all the shapes/sizes of pins I need. I do hella swaps!! lol.

 

very true, so simple, why i didnt think of it is beyond me. the engine has the harness, granted its for automatic, but the two wires should still be there to use anyways.

 

You should look by the passenger shock tower because most 4g Si's HAVE at least 1 of the 2 connectors and it's on the passenger engine harness, small plug with green/yellow wire, mine did.

 

Ok so wtf I tried calling this place that refurbishes ecu's and stuff ( the one that's all over eBay) and they are telling me that a p28 obd1 ecu will not work with the h23 vtec because it's obd2???? Uhhh isn't that why they designed the conversion harness so that obd2 can work? Please correct me if I'm wrong.

 

They don't understand you are using a conversion harness, just get the P28.

I have one for my H2B and a P72 for my 'lude

 

Exactly what I tried to tell them. I guess that's the hard part about this engine. Socalled experts don't know **** about it apparently. Even the mechanics told me this swap wouldn't work. I don't have any way of dropping an engine so I got a shop helping me out with it.

 

Lol nvm I finally got ahold of their tech specialist and he knew what the deal was.


So a little off topic but with this engine set up to my old h23 tranny I'm assuming I should keep shifting at 6500 or is the tranny rated for higher. Iv heard that the engine red line is at 7200 but I don't wanna push it fearing that I'll fxck up the tranny. Eventually I'll probably swap a h22 tranny on there but not right now

 

Trans isn't going to be affected by revving it out.

And again...I would suggest just using a H22 ECU. Like a JDM H22 OBD2 ECU or a U.S 96 spec H22 ECU (the U.S. one is hard to find).

 

Doesn't the OBD2 JDM one have an immobilizer?