o2 sensors; please help!

Hey guys, its been a while,

So over the summer I bought this '90 Miata with a '97 engine swapped in. the guy i bought it from didnt really know too much about the car, or the swap. well, my car fails emmisions and i realize there is no o2 sensor, but i found the plug it goes in. however, i dont know if its for a '90 o2 sensor or a 97. the plug has a 4 wire connector in the square formation.

Pic of the plug:
http://www.flickr.com/photos/87845403@N00/4353393467/

Which sensor should I buy? Where is the best place to buy a cheap miata o2 sensor??

also, I couldnt find where you actually screw in the sensor,

Many thanks,
pogo

Think the '90-'93 used a 1 wire setup the '94-'97 uses a 4 wire setup.

What is causing the car to fail? NOX?

yea, nox are up around 3300, everything else is in the green

"the '94-'97 uses a 4 wire setup."

are all the 4 wire sensors used for na miatas the same? I'm just worried i'm going to buy the wrong one

Should be a bung in the exhaust manifold for the 02 sensor.

I've used the Bosch replacement O2 Sensor you can get at any Autozone or parts store of your choice.

But man 3300 that is really high isn't it? What is the states limit on NOX??

You will need to use a 1 wire 90-93 O2 sensor, as that is what your wiring harness is.

limits around 1500.

I already put in a catalytic converter in, and its still that high,

Quote:

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Originally Posted by pogo

"the '94-'97 uses a 4 wire setup."

are all the 4 wire sensors used for na miatas the same? I'm just worried i'm going to buy the wrong one

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This may help.

Quote:

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Originally Posted by Titus

You will need to use a 1 wire 90-93 O2 sensor, as that is what your wiring harness is.

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You sure?

Looks like the same wiring that is on my '94
http://lh6.ggpht.com/_ar4NWGG0rGY/S3...2/IMG_1150.JPG

Here is where the 02 sensor is located on a '94.
http://lh3.ggpht.com/_ar4NWGG0rGY/S3...2/IMG_1151.JPG

Strange... his picture is of a 94+ 4 wire, but if the car is 90-93, it should be using the 1.6 wiring with the 1 wire plug. I found this info on the swap:

Quote:

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If you want to use stock parts, use the upper section of the 1.8 exhaust and the downpipe from the 1.6. This will let you retain your stock cat although you will have to weld a bung in place for the O2 sensor. If you use a 1.8 header, you'll also need a 1.8 catalytic converter. Use the 1.8 injectors with the 1.8 fuel rail, but all 1.6 wiring including the injector wiring harness. Basically, if it's electrical keep the 1.6 parts and everything else comes from the 1.8.

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It confirms that it should be the 1.6 wiring, and also points out that he may not have a bung for the O2 sensor.

yea, i just searched again and i cant find a bung for the o2 sensor. so if i weld one on, would the 4 wire work? or is it more complicated then that

You sure it doesn't have one??
http://www.too-many-parts.com/rs/ima...2_downpipe.jpg

Quote:

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Originally Posted by Titus

Strange... his picture is of a 94+ 4 wire, but if the car is 90-93, it should be using the 1.6 wiring with the 1 wire plug. I found this info on the swap:



It confirms that it should be the 1.6 wiring, and also points out that he may not have a bung for the O2 sensor.

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His picture looks like the 4 wire. Guess you can't just use a down pipe from the 1.8?

Looks like you get to add a bung pogo. How did the previous owner get it to pass the last inspection??

Quote:

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Originally Posted by POS Racing

His picture looks like the 4 wire. Guess you can't use a down pipe from the 1.8?

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On a 1.6, the bung is in the header, while the 1.8 has the bung is in the downpipe. If you use a 1.8 header connected to a 1.6 downpipe, you can still use the 1.6 CAT, but don't have a bung for the o2. If you use the 1.8 header and downpipe, you have a o2 bung, but need to get a 1.8 cat.

Quote:

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Originally Posted by pogo

yea, i just searched again and i cant find a bung for the o2 sensor. so if i weld one on, would the 4 wire work? or is it more complicated then that

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See the instructions below. They explain how to install a universal 4 wire o2 sensor in any Miata.

http://www.flyinmiata.com/support/in...ire_sensor.pdf

Quote:

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Originally Posted by Titus

On a 1.6, the bung is in the header, while the 1.8 has the bung is in the downpipe. If you use a 1.8 header connected to a 1.6 downpipe, you can still use the 1.6 CAT, but don't have a bung for the o2. If you use the 1.8 header and downpipe, you have a o2 bung, but need to get a 1.8 cat.

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Ah well that answers that!

Wonder if the new cat is going to be killed by those high NOX numbers??

Found this drawing of the 1.6 1 wire O2 sensor & it shows a connector.
http://www.partstrain.com/images/pro.../250-21035.jpg

Quote:

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Originally Posted by POS Racing

Ah well that answers that!

Wonder if the new cat is going to be killed by those high NOX numbers??

Found this drawing of the 1.6 1 wire O2 sensor & it shows a connector.
http://www.partstrain.com/images/pro.../250-21035.jpg

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Yep... that is what it looks like on my 1.6. I replaced mine with a 4 wire using the FM instructions I posted, but still use that plug with it.

Quote:

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Originally Posted by Titus

Yep... that is what it looks like on my 1.6. I replaced mine with a 4 wire using the FM instructions I posted, but still use that plug with it.

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Looks like from pogo's picture his has the 4 wire setup on it already, wonder if the previous owner has it setup correctly.

http://www.autopartsfair.com/images/.../250-24245.jpg
http://farm3.static.flickr.com/2744/...76331142a9.jpg

Does anyone have an OBD II reader? Not just a scanner, but one that can give O2 sensor readings? Gabkwong needs to use one for his O2 sensor problem.

Vatozone will read codes for free.

Quote:

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Originally Posted by motorollow

Does anyone have an OBD II reader? Not just a scanner, but one that can give O2 sensor readings? Gabkwong needs to use one for his O2 sensor problem.

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You can test the 02 sensors - http://mr2.com/TEXT/O2_Sensor.html