Ttruth be known I love the damn car more than children, but I am having a hell of a time with it. Before I bought it I was told it was in a "small" front end collision. Turns out that small collision was a bit bigger than I was expecting.. The car is cosmetically beautiful.. but under the hood is a little messy and im trying really hard to get it back to perfect. before I bought it a "jdm downpipe" was installed and while putting a bov in today I noticed what looked like an o2 sensor at the top of the down pipe. Its not connected to anything. I hooked the car up to a wideband and im seeing around 13.8 at idle. So Ive spent a long time searching the forums today and I cant seem to find the answer im looking for. Is this the O2 sensor and how important is it to the cars functionality?

thanks in advance, Michael

 

Unless someone jammed an EGT on there, that's probably the O2 you are seeing.

Some people have run without the O2 being connected without too many problems. I would say though that without it connected, you are probably idling quite rich and having some bad gas mileage.

 

thanks for the quick response, thats exactly what I thought... good to know

 

i though the O2 sensor is only used while in cruise control to give you better gas millage...

 

also used for tuning.... and such...

 

its used for your cars computer. It helps fuel mileage among other things and tell the computer if it too rich or what. With it unplugged your car will run rich i would imagine (but not 100 percent sure) similar to open loop like when your car is in cold startup.

 

The stock narrowband 02 sensor should NEVER be used for tuning, or even an A/F gauge for that matter.

The ecu uses feedback from the 02 sensor at idle, cruise, and light throttle to maximize gas mileage. Once boost hits, the ecu switches to the built-in fuel maps. If you remove your 02 sensor, the ecu will resort to a fuel map and you will run richer than need be at idle and cruise.

 

Another question, this might sound kind of dumb :P but where is the stock horn "supposed" to be. mine dosent work, so I checked the relay and buttons and everything is clicking.. which leads me to believe the horn was left out after the accident. Also since im having so many problems and tired of asking and searching the forums... what is a good repair manual to buy? ive used chiltins but never really liked it, just wondering what my options are?

 

Just download the factory service manual from www.iluvmyrx7.com for free. You can also buy it from www.mazdaformance.com or get one from Ray Crowe at Malloy Mazda.

The horns (2) are located at the outside edges of the main intake in the bumper (to the sides of the radiator). You can find info about the horn in the Body Electrical Manual, section F2.