5th gen 2.0l to 4th gen jdm h22 engine swap

yorke58 · Post by **yorke58** » Sun Mar 16, 2025 3:58 pm

Hi all.

I've posted before about this conversion. Im at the point where I need to get the car to talk to the engine.

I've got

4th gen ecu
4th gen engine harness
4th gen ecu to wiring loom cut out off the old 4th gen car with to me looks like a rats nest.

My question is how do I get the 5th gen talking to the 4th gen ecu then from the ecu to the wiring harness.
I'll attach a pic

Cheers

Post by **Vtecmec** » Sun Mar 16, 2025 7:30 pm

The pics not showing for me?

I think you could do the following:

Fit ECU with OBD 2 to OBD 1 plug convertor and keep the 5th gen wiring harness, though you might have to swap the dizzy and alternator wiring slightly (or maybe not?). Fit 4th gen dizzy, injectors and alternator.

You'll also need an injector resistor box and injector plugs whatever route you use if your using the 4th gen ECU.

yorke58 · Post by **yorke58** » Sun Mar 16, 2025 8:41 pm

If i use the convertor and keep the 5th gen wiring the h22a engine loom doesn't have the same ends in the engine bay. The f20 has 4 large plugs 2 gray 2 blue. The h22a has 2 large plugs 1 gray and 1 blue and 2 smaller gray plugs.

I've got both types of dizzy both alternators. I dont have the resistor box are they easy to get.

Electrics arnt my strong suit

I've added another pic i think it's public to view

https://imgur.com/gallery/h22-8NCz2WA

Cheers

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Mon Mar 17, 2025 8:21 am

@fithotblonde can you chip in with any help on how you did this?

Andreika609 · Post by **Andreika609** » Mon Mar 17, 2025 9:48 am

Hey. buy a conversion harness to 4gen ecu. Use 5gen f20 engine harness . Add vtec, vtec oil pressure switch plug ( if you use one) . Get a resistor box , wire it to injector harness. ( google info for B series conversion from internet its there. ) Knock sensor , not sure about it now. Alternator plug redo also . Cant remember more but you find out by googling to the forums

Good luck

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Mon Mar 17, 2025 10:14 am

For the differences you have in plugs on the engine loom, you can buy OBDII-ODBI convertor leads for each of the components.
One of them here, for example
https://www.ebay.co.uk/itm/185931448063

yorke58 · Post by **yorke58** » Mon Mar 17, 2025 12:36 pm

Sounds wild using the old wiring loom. But it makes more sense what ya saying. Just adding 2 or 3 wires than tackling that rats nest ive got.

With having the 2.2 loom i can use the connectors. Then install the resistor box.

Cheers