I have 2 NTK 2H29 4 wire o2 sensors. Obviously I only need one. Anyway...I searched a bit and couldn't find how to wire it up. I'm having running/Autotune troubles again. When I first start the car up it misfires quite a bit until its warm. When the Autotune turns on the car bogs HARD and misses. I'm pretty sure the 1 wire o2 I have now is the culprit. I still have the Greddy d/p.

They have 2 white wires, a grey and a black. How should this be connected? Thanks!

 

The two white wires go to your 12 volt supply, doesn't matter which is + or -.

Your black goes to a good solid ground that is common with the ECU(there is one on a screw to the motor by the CAS. The grey wire goes to where your single wire was going before.

 

Above is incorrect. The grey wire is your ground, the black is your sensor wire.

Sorry if I gave anyone else the wrong information. I just pulled one out and tested it.

 

I updated my diagram. I'm hoping to get this installed soon. The government needs to hurry up and give me my refund so I can get my wideband! I was planning on doing both at the same time, but I'll pop this is really quick. Thanks!

 

http://mymiata.paladinmicro.com/Miata4-WireO2.htm

This is the site i used when i wired mine up. make sure you actually wire up the o2 sensor ground to the same wire as the ECU ground. Going to body ground is not good enough.

And yeah, your symptoms are EXACTLY the same as my symptoms when i had a bad O2 sensor: bogging and hesitation (almost sounds like hitting fuel cut) when the car is cold and trying to enter boost for the first time.

 

Great link supersaiyan! Thanks! This is exactly the symptoms I've got. I bought the 4 wire sensor today, and it'll go in during the week! MT.net FTW!