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Discussion Starter · #1 ·
Okay so i am trying to do the popular H22 swap in my car. The only real concern i have is the wiring harness. I have a few friends who are good Honda mechanics, and they were trying to help me figure out what i should do. Their ideas were that i could re pin the computer with my harness (He did this when he put a b18 in his hatchback,) or that i could find a harness that converts my harness to work with a newer computer. The only conversion harnesses i could were for the si model so i'm not sure they would work with mine. As far as re pinning the computer goes, i feel that could be done with the right diagram. Does any one know where i might be able to find this information? Or if is even possible?
 

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No one has re pinned the ecu. You know you need to re do the fuel lines and everything right? You have to convert from s to si then to h22. :) id reccomend swapping in a 90 91 harness and adapting it to work with the 88 89 components. That's what I did to swap fi.
 

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I have an old build thread that may be helpful. Also there is awriteup on how to convert s to si on prelude3g.com
 

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Discussion Starter · #4 ·
Yes, i am planning on running steel braided lines for fuel. I have read alot on the swap, and what other people have done. I am really starting to find out how much of a b**ch this swap is. Do you think re pinning it is possible? I think there is a way around rewiring the whole car i just have to find it. I will check out your thread.
 

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Well the plugs for the ecu will be different but I assume that's what you mean by re pinning. That will be a tough process. I would still do it if I were you. But you will need to run extra wires for knoc and vtec. There's a few more. I think it just works out better to convert the whole car to obd1 cuz then you get a vss instead of a cable speedo and you don't need to repin anything. You can just plug in a different ecu and roll with it. You still need a couple extra wires tho.
 

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Discussion Starter · #6 ·
I'm planning on going with an 0bd1 computer, i mean i want to pin my interior harness to the new computer if possible. I can add any wires if needed
 

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I know what you meant. Check the pinout diagrams for both ecus
 

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It is going to be much easier but labor intensive to just swap to the Si interior harness and all the brackets.

It is recommended to swap in the hardline fuel lines, you do not want to potentially spring a leak or accidentally get snagged down the road. Now we have another member who ran the ss line and it works great, its only a recommendation so the choice is yours.

I know what you are trying to do, but if you and your friends are not familiar with the wiring you can take even longer to get your swap finished and eventually give up.

Its been done many times before. Just do it right the first time, and go the junkyard and pull the Si harness out of an 90-91 and then the engine harness as well, and pretty much everything connecte to it.

You will be glad you did.
 

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Dammmm you should just get a 90-91 Si....save yourself a huge headache. But if you're friends are hond a knowledgeable and know what they're doing you should be fine but this is gonna be labor intensive. You have guys here with the 90-91 Si(which is the ideal candidate for a H22 swap due to it being OBD1) running a h motor and they still be having problems due to the swap. Just something to think about.
 

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first off, obligatory "fk tha haterz" :p

but it really isn't that big of a deal, I want another 3G H and would specifically look for an S model to do it to anyways, instead of an Si. I ran SS lines for my fuel feed and used the stock carb feed line for the return, it all works well with the Si pump and tank.

For the wiring, just find a 4th gen VTEC fender harness, your ECU will plug right in, and so will the engine, you'll really only have to wire in the main relay and i think another thing or two. It really isn't that bad. But using a stock harness you're putting yourself behind the 8-ball and setting yourself up for failure. If you have to swap a fender harness, why not swap a plug and play one?
 

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^i like what j is saying here. sounds much easier. i only reccomend the b21 body harness for simplifying certain things. just keep your stock harness as you will need to swap connectors over for things like the turn signals and such. plus going that route you can swap in a 90 91 cluster and have no vss worries. do the research well as there are a lot of little things people dont think of during such a swap. id say nylon braid for your fuel lines. its a little more pricey but you dont have to worry about it rubbing anything and causing wear. also id still run the lines in the car around the stock locations to keep it out of harms way.

j if he gets a fender harness from a 4g will he need to do anything to the body harness to make it work with the cluster? im sure he will at least need a 90 91 cluster since the h has a vss.
 

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Correct, I forgot about the cable to electronic VSS, though I would have to imagine that the cable VSS would fit, no? Can you not run an 88 trans in a 90 car without having VSS issues? Because I know 90 and H VSS are the same.

But all that aside, it would be easier to put a 90 cluster in there and run 1 wire from the ECU as opposed to pulling the dash and swapping the dash harness. I would get a spare dash harness from something with an electronic cluster, find the wire and then you should be able to de-pin it from the one harness and re-pin it to the connectors in your existing harness, since I would assume that there is a spot for that wire to go to on your existing connector.

As for your your choice of hose, nylon braid covering would work, I've done that on 1000HP cars with no issue, you just have to worry about turning it too much and collapsing the hose, we had fuel starvation issue on our EVO X because of that and it cause all sorts of issue including pump burnout, and it was a pain to track down. I like the braided SS simply because its tough and you'll know if you're bending it too much. But I run mine outside of the car, 1 should I ever spring a leak it will be outside the car, and 2, most sanctioning bodies mandate it be outside the car, not that you'll ever run into the issue, just FWIW. And outside the car you don't really have to worry about it rubbing on anything, and I've tied mine down to where it doesn't move and where it does, it has sheathing on it. But you can route it alot cleaner looking outside the car. But its preference, nylon or SS, inside or outside, it doesn't make a difference.
 

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Correct, I forgot about the cable to electronic VSS, though I would have to imagine that the cable VSS would fit, no? Can you not run an 88 trans in a 90 car without having VSS issues? Because I know 90 and H VSS are the same.

But all that aside, it would be easier to put a 90 cluster in there and run 1 wire from the ECU as opposed to pulling the dash and swapping the dash harness. I would get a spare dash harness from something with an electronic cluster, find the wire and then you should be able to de-pin it from the one harness and re-pin it to the connectors in your existing harness, since I would assume that there is a spot for that wire to go to on your existing connector.

As for your your choice of hose, nylon braid covering would work, I've done that on 1000HP cars with no issue, you just have to worry about turning it too much and collapsing the hose, we had fuel starvation issue on our EVO X because of that and it cause all sorts of issue including pump burnout, and it was a pain to track down. I like the braided SS simply because its tough and you'll know if you're bending it too much. But I run mine outside of the car, 1 should I ever spring a leak it will be outside the car, and 2, most sanctioning bodies mandate it be outside the car, not that you'll ever run into the issue, just FWIW. And outside the car you don't really have to worry about it rubbing on anything, and I've tied mine down to where it doesn't move and where it does, it has sheathing on it. But you can route it alot cleaner looking outside the car. But its preference, nylon or SS, inside or outside, it doesn't make a difference.

Justin,

Can you please document and do a write up on your swap for those S model luders who are thinking about the H22 swap. I need specifics on what you did to make your swap work and high resolution pics as well. I would like to use those pictures with the other pictures I have collected to be posted in the HondaTuning Article.

It would really help especially since I am putting together a Tech Article for HondaTunning magazine. They are waiting for me to get it together and submit it to them.

They said they will run it as long as I provide them with the information and pics that they need. Your S to H22 swap will help all to see that no matter what model of 3rd gen, the H22 swap is very doable.

Thanks.
 
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