HX O2 Sensors=

[civic lover]

I picked up a 97' HX that was a theft recovery. They ended up taking the O2 sensors. I understand I should get a good L1H1 5 wire sensor. Any suggestions through who?

What about the 4 wire O2 sensor? Who should I buy that from? Does it matter?

[GasSavers_BEEF]

not a honda guy, but

I thought the 5 wire was a wide band and anything less was just a regular O2 sensor and you need the wide band for lean burn and all.

I am sure if I am wrong that someone will correct me.

[Danronian]

OBD2 Hondas have a pre and post-cat. o2 sensor.

The pre-cat will be the 5-wire, the post-cat the 4-wire.

[civic lover]

So the 4 wire... does it need to be a certain brand, or are all of them acceptable? Any part numbers to watch for (ex. L1H1)?

[civic lover]

Another question to add. What would be the affects of using a header instead of the oem exhaust manifold with cat? Would the secondary O2 sensor work properly?

[civic lover]

I hate to do this but I have to bump this thread to get #4 and 5 response answered. I need to start ordering parts so I can get this thing on the road. Any and all info is greatly appreciated.

[beb]

Since there's been no authoritative response, I'll offer my shade-tree opinion:

If you don't want lean-burn, it doesn't much matter what you do. I've seen a running HX that had a four-wire O2 sensor plugging the hole where the 5-wire should go - completely electrically isolated from anything, with the five wires dangling from the connector just as cleanly cut as the four on the sensor. I've seen another with a lovely and expensive header in place of the OEM exhaust, as well as a 'cold air intake', and running off of a P28 (an arrangement assembled by a kid that heard the word 'VTEC' and took off open-loop from there), which ran much like one would expect of an engine with half of its intake closed and using another cam's fuel maps. Obviously, neither of these ran in lean-burn mode, but they did run well enough to drive without the owners being compelled to fix anything (to the contrary, the ricer was quite delusional about the results).

If instead you want lean-burn, then any deviation from the OEM equipment risks breaking that function. For example, if you get rid of the close-couped cat, the wideband O2 sensor looses a major source of the heat that it needs to function. Put in a counterfeit wideband O2 sensor, and the ECU may not get calibrated AF data.

The cheapest wideband O2 sensor that is made for this application by a reputible manufacturer is probably the Walker 250-25001, but in my thread asking if anyone has used one of these, there's been zero feedback. I just got one in-hand today, and it looks better made than a genuine NTK L1H1 (e.g., wiring stress relief at the sensor attachement), but it will be weeks before I try it.

I don't know anything about the after-cat 4-wire, but suspect that it could go anywhere after the cat that there is enough heat, but the OEM position is excellent from a wiring perspective.

Does it need to be said that you have to use O2 sensors listed for this application; e.g., the Bosch 4.2 5-wire uses a completely different calibration resistor scheme than the L1H1/L2/H2 and won't even begin to work if used on an HX?

[civic lover]

Originally Posted by beb

If instead you want lean-burn, then any deviation from the OEM equipment risks breaking that function. For example, if you get rid of the close-couped cat, the wideband O2 sensor looses a major source of the heat that it needs to function. Put in a counterfeit wideband O2 sensor, and the ECU may not get calibrated AF data.

Is there that much of a difference, as far as heat is concerned for the O2 sensor, when switching from a stock exhaust manifold to a header?