Recently picked up a civic HX with the CVT trans. I can't stand this thing so I'm converting to manual.

I know that the OBD1 ECUs can be converted to manual with the removal of 1 resistor, as I've done it a few times, but I haven't ever looked into OBD2 auto to manual conversions while staying OBD2.

This will be a daily driver, so no engine mods, etc. so I want to stay OBD2.

If I just run the auto ECU, which is designed for 4 wire o2 sensor operation, will it run like ***? Throw check engine light?

If I get the manual ECU, are they all 5-wire o2 sensor? Is there a CA model with 4-wire o2 sensor that might be perfect for what I need?

Anybody head down this road before?

 

according to the O2 part numbers... (and corresponding ECUs)

for the HX...
36531-P2E-A01 (fourwire)
used on 96-00 cali & 49state CVT trans

36531-P2M-A01 (wideband)
used on 96-00 cali & 49state manual trans


running an OBD2 CVT trans ECU on a manual trans car will result in problems. CELs would be the least of them.


unfortunately you'll either have to pony up for the wideband and run a manual trans ECU, or deal with the CVT trans... or run OBD1 and tune it to run right.
BTW, running the wideband is far from the end of the world, the fuel mileage is a welcome sight with fuel prices.



BTW, here’s the ECU codes for the HX [37820-P2N-*] (in case you need them)

A21 - 96 5sp
A22 - 97 5sp
A31 - 98 5sp
A32 - 99-00 5sp
A33 - 99-00 5sp
A61 - 98 CVT
L21 - 96 cali 5MT
L22 - 97 cali 5MT
L31 - 98 cali 5MT
L33 - 99-00 cali 5MT
L61 - 98 cali CVT

Oddly, only the 98 HX is listed to have the CVT trans with ECUs. But the O2s show for 96-00 HX CVTs.

 

Much appreciated man.

Now I'm off to figure out the passenger mount issue. This should go over fairly easy, just gotta fork out the cash for that damned o2 sensor, along with the HX 5 speed intake manifold so I get the IACV fix I'll need.

 

I would really only do this swap if your CVT transmission is going bad because this swap will be very complicated and expensive and not worth the effort. There is a LOT more to converting from an HX CVT to Manual that I know you don't know about. The sensors in the intake manifold, ignition, etc. are different enough to be an issue that you won't be able to easily overcome by getting a manual transmission and manual ECU. An auto to manual transmission swap is difficult enough as it is but being the type of car that this is, it's going to be WAYYY harder and you'll have a pretty good chance of screwing up it unless you completely gut the car of its old engine/transmission and swap in something else. If you want to get an idea of how different these cars are, check out the helms manual and look at the electrical connector identification page, say page 23-16 and look at the A/T vs M/T connectors.

 

It would be a lot easier if you could find an hx parts car. I think the biggest hurdle would be the mounts for the transmission. You would definitely need to do some re-wiring but if you had another car hopefully you would at least have most of what you would need. I'd swap the engine harness out and would be simpler than trying to rewire the current harness to get it to work.

 

O2 - search for a NGK L2H2, much cheaper than going through honda, identical part.

 

For electrical, it may be cheapest and easier to just get a harness from the junkyard. The yard near me is pretty awesome and charged me $10 for the chassis harness I needed. There's gotta be info on the mounts needed. The rest of the auto to manual swap is pretty easy.

 

It's not JUST the harness. The manifold's EGR and IACV valves are completely different on the automatic D16y5 vs the Manual D16y5. Those are expensive parts and not easy to source FYI. There are a myriad of other reasons why this swap won't work.