H23A vtec swap into 02 EX MT

[btr24evr]

Hi, new member here!

My 02 EX MT has about 270k miles on it and recently got a CEL for cyl #3 misfire. Turns out the compression is getting worse by the day. I have to do smog in a few months. So even if the car doesn't die, I wouldn't be able to drive it around legally.

I live in California so the car is in great shape. Paint in great condition. Upon inspection, all the suspension components and bushings are crack free. So the car can probably go another 200k miles with a "newish" engine. The downside of being in CA is that I'd have to keep the car OBDII.

I've been doing a lot of research on how to swap the F23A out for a JDM H23A vtec, for fun. But it seems I might actually have to do it sooner than later. I haven't been able to find a comprehensive source on this exact drop. So I want to see if one of you out there have done the H23A swap in the 6th gen keeping it OBDII. Here's what I have so far. I'd appreciate any help or comments.

Engine: JDM H23A VTEC

Transmission: T2T4

Engine Mounts: only need to modify stock F23A driver side mount to fit

ECU:
- Prelude automatic ECU: P5M-L55
- Have to do auto to manual mod
- Have to get immobilizer emulator chip and solder it in to bypass stock immob
- Will have to make a OBD2B to OBD2A conversion adapter to allow the stock Accord harness to plug into the H22 ecu
- I am not going with the manual H22 ecu because those things are super expensive on ebay

Crank sensor:
- I have to get a H22 oil pump and swap in my F23A crank and TDC sensors

Distributor: have to get a H22 distributor and coil to replace the H23A's

Power Steering:
- H22 p/s bracket
- stock F23A p/s pump
- H22 harmonic balancer & belt

Exhaust:
- H23A exhaust manifold with H22 downpipe
- weld bong for O2 sensor into H23A exhaust manifold or downpipe, but I think I will have to do this just before the cat since that's where the stock Prelude's location is.
- for now I think I will just have an exhaust shop get the H22 downpipe connected to the stock accord exhaust.

Wiring: Not exactly sure yet. I will probably figure this out when I have the H23A to compare next to my old F23A



Do you guys see any issue with what I have so far? There are also a a few things I'm unsure about.

- Is it easy to modify the stock F23A driver side mount to fit the H23A?

- Have any of you had success running the H22 P5M-L55 automatic ecu (with mods) with the H23A?

- Can I use my stock F23A harmonic balancer for power steering?

- I know some people kept the H23A distributor and just extended wires in the stock harness to use the sensors rather than getting the H22 oil pump, distributor and coil. Has anyone had success doing this with the H22 ecu and keep it OBDII compliant without and CEL?

 

[btr24evr]

Some things I forgot about.

My stock F23A AC compressor and alternator should bolt right onto the H23A without any mods.

If I want to keep cruise control, I will have to swap over the F23A throttle cable pulley.

I will probably need to get a new clutch and flywheel.

I'm just trying to get the car running error-free spending as little as possible. I will inspect the timing belt, but most likely I will not do the belt and water pump til a later date. Eventually, I will have a custom 2.5" exhaust made with a vibrant muffler and resonator. Trying to keep it sounding as stock as possible.

 

[Jordan_H]

I wouldn't use an automatic Ecu. If you don't need emissions I would do a p28 with h22 basemap and have it tuned. Hondata s300 seems to be everyone's favorite.

 

[RawCarnage]

I wouldn't use an automatic Ecu. If you don't need emissions I would do a p28 with h22 basemap and have it tuned. Hondata s300 seems to be everyone's favorite.

he needs to keep it obd2 though which is a hard thing to do lol. there is a odb2 ecu that you can use that doesnt have an immobilizer from a 96 prelude. or you can try using a h22a4 ecu and have the immobilizer removed.

 

[btr24evr]

Yea, I will need the car to stay OBDII and pass smog in Cali. I think I have the immobilizer issue covered. I'll either get a bypass chip from Doctronics or eBay and solder it in.

I guess I might have to go with the H22A4 manual ecu. I just remember reading somewhere someone used the auto ecu and modded it to manual. The reason is the manual ecu is much harder to find and cost $100 more.

 

[RawCarnage]

Yea, I will need the car to stay OBDII and pass smog in Cali. I think I have the immobilizer issue covered. I'll either get a bypass chip from Doctronics or eBay and solder it in.

I guess I might have to go with the H22A4 manual ecu. I just remember reading somewhere someone used the auto ecu and modded it to manual. The reason is the manual ecu is much harder to find and cost $100 more.

i dont think you can mod a obd2 auto ecu to manual. with obd1 you can just de-solder 1 connection. i think the manual ecu would be best in the long run if it turns out to work just fine with the engine.

 

[Jordan_H]

If you mod the automatic Ecu you'll get a CEL and then you can't pass emissions. Best bet is the 96 prelude manual Ecu or prelude Ecu with immobilizer removed. Good luck with either of those.

 

[whitegourd]

Exhaust:
- H23A exhaust manifold with H22 downpipe
- weld bong for O2 sensor into H23A exhaust manifold or downpipe, but I think I will have to do this just before the cat since that's where the stock Prelude's location is.
- for now I think I will just have an exhaust shop get the H22 downpipe connected to the stock accord exhaust.

Are you planning on getting it barred? If you are, you'll also need to make sure you have the cat that goes along with the engine. When I got mine barred, they looked at everything, ecu, even the evap canister as that also has to come from the H engine. It took me 3 rounds to finally get mine barred.

The only problems I ran into when I got mine barred was that the rywire adapter for some reason didn't have a pin out for the evap sensor, which kept throwing a P1457 code after every driving cycle reset.

If you just do the swap and try to pass emissions w/o getting barred, you're going to have to hope the person doing your emissions doesn't know that the car has been swapped with a different series engine, otherwise they may have you head straight to a state ref.

 

[btr24evr]

If you mod the automatic Ecu you'll get a CEL and then you can't pass emissions. Best bet is the 96 prelude manual Ecu or prelude Ecu with immobilizer removed. Good luck with either of those.

Looks like the H22A4 ecu will be my best bet. Would love the 96 prelude ecu but those things go for half the price of the engine. A $30 immob emulator seems much more reasonable.

 

[btr24evr]

Are you planning on getting it barred? If you are, you'll also need to make sure you have the cat that goes along with the engine. When I got mine barred, they looked at everything, ecu, even the evap canister as that also has to come from the H engine. It took me 3 rounds to finally get mine barred.

The only problems I ran into when I got mine barred was that the rywire adapter for some reason didn't have a pin out for the evap sensor, which kept throwing a P1457 code after every driving cycle reset.

If you just do the swap and try to pass emissions w/o getting barred, you're going to have to hope the person doing your emissions doesn't know that the car has been swapped with a different series engine, otherwise they may have you head straight to a state ref.

Will probably not try to get it barred. I should know someone doing emissions who will 'overlook' the different engine.