How do I convert a CA VX to a lean burn model ?
 

Now that I figured out that my recently purchased 93 Civic VX is a CA car, and thus apparently not one of the lean burn models, is the conversion possible? Hard? Easy?

ECU and O2 sensor from a non-CA VX to start, I suspect, but what else?

Shouldn't be too bad...prolly just the ecu, 02 sensor, and some wiring.

The only thing I would be concerned about is the location of the car now. I forgot if you were located in CA or not, but there are no lean-burn CA models due to not passing emissions there.

If you were to do this, I'd recommend getting a 2nd bung welded onto your exhaust so you can have both O2 sensors installed. That way to convert back, you swap ECUs and reconnect the old O2 sensor.

My understanding is that a non-CA car will pass the smog tests, here. Although they were not able to sell them as new, and their NOX is higher than the CA model, my impression has been that they will still pass.

I think the 3 things you have identified are all that is required. I think your transmission is geared for CA, so your final RPM won't be quite as low as a non-CA car, but it still should be high 40's, I would expect.

I need to figure out the easiest way to wire in the 5-wire O2 sensor, given that I have a 4 wire O2 and harness. The web is loaded with info on going from 5-wire to 4-wire, but the reverse is not as clear from these postings and I have yet to find a 4 to 5 wire set of instructions.

Has anybody done this and therefore can recall the "this color wire to that position in the 4 wire harness.... that other wire straight to the ecu position xxx"

I have a schematic, but from a $16 shop manual (Haynes or Motors or something), thus I am less than confident that the colors and pin positions are correct..

The ideal situation would be to be able to swap the O2's, use some of the existing 4-wire wiring in the existing harness, and then run the additionals to the closest place in the engine compartment that exposes the correct ECU slots (this assumes that at some point near the ECU, the wiring for the CA versus 49-state VX is basically the same and the difference is only that at some point they dead end the 5-wire O2 wires....)

I need to convert my R-18 to lean burn. Like Honda intended.