No O2 Sensor

zephyrus17 · Postby **zephyrus17** » Wed Mar 07, 2012 4:27 pm

So I replaced my Cat, pipe and muffler with one ordered from GoMiata last Saturday. The website says they include the bung plug for NA6 cars because the other models have two holes. When my midpipe arrived, there was only 1 hole for the O2 sensor, so, technically, no bung plug was needed. That's fine and all, but I realised that when I removed the midpipe, I didn't need to detach the old O2 sensor, because there was none in the first place! I'm going have another check under the car tonight, but all this seems to indicate that I've been running my car without an O2 sensor all this time? Is this even possible? I'm quite confused as to the situation I'm in now.

hks_kansei · Postby **hks_kansei** » Wed Mar 07, 2012 4:35 pm

I'm pretty sure the O2 sensor isn't mounted in the midpipe.
It's up on the headers.

edit:
Not a stock manifold (and from an NA8), but the bung is in roughly the same place as the stock one, and from memory the same position as the NA6.
http://rupewrecht.com/forsale/fs_ms_mx5 ... ld_na8.jpg

93_Clubman · Postby **93_Clubman** » Wed Mar 07, 2012 4:41 pm

Aust delivered NA6 wasn't it? From memory the NA6 O2 sensor was just down from the headers like the NA8. JDM had another (heat) sensor in the cat. If no O2 sensor, then you'd be running in open loop, like if the O2 sensor was US.

zephyrus17 · Postby **zephyrus17** » Wed Mar 07, 2012 5:01 pm

Yeah, I was reading around on google and it seemed to suggest that it was on the headers. So I'll need to just get the bung plug for the midpipe O2 sensor hole. Should I be replacing the header O2 sensor anyway? Mine is probably OBD-I, and I'm not too sure about diagnosing the sensor's effectiveness.

hks_kansei · Postby **hks_kansei** » Wed Mar 07, 2012 5:19 pm

I don't think MX5's used OBD anything up until the NB8B

Everything before that was a silly Mazda only thing I think.

Regardless, on Miata net (maybe in the garage) there's a writeup about how to pull the fault codes from an NA, it involves jumping different points of the plug and counting beeps.

Either way, it might be worth changing the sensor, I don't think they're expensive. ($50 to $80 rings a bell?)

zephyrus17 · Postby **zephyrus17** » Wed Mar 07, 2012 5:23 pm

Ohh I didn't know that about the OBD. But, yes, thanks to you two for the help on the matter!

hks_kansei · Postby **hks_kansei** » Wed Mar 07, 2012 5:26 pm

http://www.miata.net/garage/Engine_Diagnostics.html

Worth noting, my comments on OBD may be completely wrong.
Someone with more knowledge would be better to comment.

93_Clubman · Postby **93_Clubman** » Wed Mar 07, 2012 5:38 pm

Thought it was OBDI, but could be wrong. Pretty sure Garrett refers to it as OBDI.

Btw, on the NA8 at least, O2 sensor is at the top of the pipe just below where the headers end.

zephyrus17 · Postby **zephyrus17** » Thu Mar 08, 2012 10:01 pm

Supercheap Auto had an O2 sensor from Triton for $112 delivered, which seemed a bit rich. I'm looking at a Bosch one for Holden (http://www.ebay.com.au/itm/New-BOSCH-Holden-VS-VT-VX-VY-VZ-VE-LS1-2-3-Frontera-Rodeo-Oxygen-Sensor-O2-/120858102015?pt=AU_Car_Parts_Accessories&hash=item1c23b448ff) because I couldn't find any for Mazda MX5s.

My main question is, can this work, or do I have to look for a specific model?