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I was wondering if anyone knows anything about the best O2 sensor to get for the BPT in terms of correct heat range and fit (maybe even the actual part number). I had a universal one (used for 30,000km) for my 1.6SOCH engine that was put into the BPT which was working for a while, but now has crapped out. It seems that it can't heat up enough to work properly. I have an air/fuel gauge that alway says my car is running lean, but it's actually running rich (judging by poping sounds in exhaust, the black tailpipe, and shitty gas mileage). The only time the O2 sensor really starts working is when I've redlined the car a couple times which I guess heats the O2 sensor enough, but then after a few minutes it's back to not working. I know Mazda whats like $150 or the 1.6SOCH O2 sensor, lordco about $75 and Mopac $40 (the one a currently have). But I guess price really doesn't matter if the s--- don't work right, so any suggestions on which brand to get?

Don't they use the same generic 1 wire sensor as the NA BP's?

not sure on brands, but you want to have AT LEAST a 3 wire, though 4 wire sensors are the best bet.

Mine is a single wire O2 sensor.

the bpt should have had one come with it. if not, grab one off of a dohc mx-3. but being as how you started out with a sohc, i'm not sure how you would wire it up.

I know 3-4 wire is better...but why does the BPDE have a 1 wire? I recall the B6 being the same....though I'm not a 4cyl guy.

It isn't hard to wire up a 3 or 4 wire O2 sensor from the stock 1 wire. Go to <A HREF="http://www.pacificsites.com/~hakuna/miata.html" TARGET=_blank>Hakuna Miata</A> for directions on how to wire it up. Another option is the 5 wire from the Honda VX(?).<P>All the pre OBDII engines came with the 1 wire. Even the B6T, not sure if all the BPTs came with the 3/4 wire sensor but considering the other goodies it is possible. All the 4 cyl engines came with them until about '94 over here, possibly a few '93 models. The only real reason that I can see a BPT having the better O2 is to help monitor the increased demands and the lack of a vaccum advance/retarded disty. That is really the only thing that I can come up with on this one.

Well, I found out that the BPT is one of the only engines that Mazda made with a 3 wire O2 sensor. If I had bought the wiring for the 1.8L BPT when I got the engine I would have had the correct 3 wire hook ups. But since I just used my 1.6SOHC wires I didn't, and also because I couldn't find a 3-wire sensor I went with the 4-wire wich is better anyways. So I just went out and bought a new 4-wire O2 sensor (NGK sensor that fits the V6 MX-3) and wired it up. Thanks a lot to Chris Malden for that Miata link, converting the 1 -wire to 4-wire O2 sensor was very easy. Anyways, the car runs much better now. From the moment I pulled out of Kevin Gee's driveway I could feel the difference believe it or not. <P> Conclusion: the $90 I spent at Lordco Auto Parts was well worth it. The O2 sensor is self-heated so it not only reaches operating temperature way way faster, it's also more accurate (even at idle) giving you better power and gas mileage compared to the single-wire type. <P> Thank you to everyone that responded to my question!

fyi nopi.com has the same o2 sensor for $45

Glad the site helped.