Mikeyjoe720

I have a 91 crx si converted to obd1 I am trying to put in an obd2 h22 the only thing is who had the car before me hard wired the obd1 engine harness.....how would I make it work and what ecu should I run?

browngrasscat

Hard wired what to where exactly?
I don't think a d series harness will do you much good with an H22 regardless of obd1/2. As I recall, you need the h series engine harness and an ecu, and an adapter (homegrown, eBay, hasport, etc) to fix it all up with the chassis harness. Or run the chassis independent if so inclined.

Mikeyjoe720

He hard wired the obd1 engine harness into the obd0 underdash harness like the car is permanently obd1...... u cant separate the engine harness fromm underdash harness

browngrasscat

Not fun, but can be fixed.
I find it best to map out what's there and compare to what it should be. Then draw up what you need/want, but then I like doing that stuff, a lot of people don't.
Is everything functional as far as you know?

Edit: As for the ecu; If you have the obd2 H22 harness, you can buy (or build if so inclined) an adapter harness to an obd1 ecu (that's tunable) and the chassis harness provided you sort it out (or hard wire it again). If electrical isn't your niche, contact a place like rywire, tell them what's up and they'll figure it out and build it (in exchange for legal tender of course).

Mikeyjoe720

Yes right before i bought the shell he had a obd1 gsr in it running and functional

Mikeyjoe720

Right thank u I have been trying to research it but found nothing so I figured I would try on here

browngrasscat

It's hard to say exactly without seeing it.
You can always cut wires and put plugs in.

Mikeyjoe720

Im gonna call rewire first and see what they say or suggest

4drEF

Why not just run the H22 on an OBD1 ECU?
Engines are not any particular OBD, but it's the sensors and ECU that make up the diagnostic system.
Many of the sensors can be mixed and matched and work exactly the same regardless of what the OBD is.

Really comes down to what ECU you NEED to run to support your goals.

Mikeyjoe720

That would make things alot easier. Which sensors would I have to change out and would I have to convert my alternator?

4drEF

From what I can find, there is a lot of information to say that people have taken their stock OBD2 car and converted to run an OBD1 ECU (for tuning options or whatever).
Seems all they needed to do was get the ECU and a jumper harness to allow them to plug the OBD1 ECU into the OBD2 harness.
no other mods required.

Then there are bad info posts that can be found saying they need to change injectors (which is 100% not true) and distributors (again 100% not true).
These would be true if going OBD2 or OBD1 down to pre-OBD (aka OBD0).