Moving the O2 sensor

Bunger · 02-27-2006, 05:21 PM

Please stop me and point me to the correct thread if this has already been covered. My mind has been focused on increasing my mileage lately (I'm normally a speed freak kinda guy), cause I'm tired of all the money I toss down the gas tank filler.

Reading through a number of articles, I noticed some complaints about the O2 sensor reacting too slowly to changes. In some vehicles, I've noticed that the O2 sensor is mounted a good deal downstream. Why not move it more upstream? Doing so will increase its response time.

Also, having a A/F guage mounted in some of my vehicle (mostly just to make sure I'm not running lean under high boost conditions), I've noticed that as the O2 sensor gets older, it also reacts more slowly. So maybe that factory recommended 30k miles isn't such a bad idea after all.

Any thoughts or comments?

Matt Timion · 02-27-2006, 06:26 PM

Quote:

Originally Posted by Bunger

Please stop me and point me to the correct thread if this has already been covered. My mind has been focused on increasing my mileage lately (I'm normally a speed freak kinda guy), cause I'm tired of all the money I toss down the gas tank filler.

Reading through a number of articles, I noticed some complaints about the O2 sensor reacting too slowly to changes. In some vehicles, I've noticed that the O2 sensor is mounted a good deal downstream. Why not move it more upstream? Doing so will increase its response time.

Also, having a A/F guage mounted in some of my vehicle (mostly just to make sure I'm not running lean under high boost conditions), I've noticed that as the O2 sensor gets older, it also reacts more slowly. So maybe that factory recommended 30k miles isn't such a bad idea after all.

Any thoughts or comments?

I think it's a good idea. Honda did this with all of their high gas mileage vehicles. On the Civic VX, CX, HX, STD, and some of the CRX HFs, the exhaust manifold is made in such a way that the o2 sensor reads the exhaust right away. On the other cars it is about a foot down the pipe.

I'm wondering if it is not a bad idea to swap the exhaust manifold (along with a new o2 sensor) to one that is closer to the head.

Compaq888 · 02-27-2006, 06:45 PM

also there are different types of o2 sensors. There are narrowbands and widebands. Widebands are really good.

Bunger · 02-27-2006, 06:50 PM

True, but unless you build a board that converts the wideband voltage range to the desired narrow band, you're not going to be able to easily use the stock ECU. While moving the O2 sensor farth upstream will do nothing but increase the ECU's ability to better control the fuel, assuming the CPU in that ecu is fast enough.

Bunger · 02-27-2006, 06:50 PM

Though I should note, some ECUs do use a wibeband O2 sensor, such as the 92-95 Honda VX.

SVOboy · 02-27-2006, 06:56 PM

Are you not equipped with wideband?

Bunger · 02-27-2006, 07:14 PM

Quote:

Originally Posted by SVOboy

Are you not equipped with wideband?

I have the stock wideband in the VX motor and then an "aftermarket" wieband I use for tuning in my other cars. But under normal operating conditions, the B18c and the Volvo use a narrowband O2.

SVOboy · 02-27-2006, 07:18 PM

Ah, well, I forgot about those other cars, cuz they suck I guess. But good to here you're using the wideband with the z1,

What wideband do you tune with?

Bunger · 02-27-2006, 07:30 PM

I tune mostly with the Innovate LM-1 system, but I've also used some home-brew VX and VW based wideband systems.

I really wish my Volvo got better mileage, but I can never seem to get better than 12-13 MPG cruising at 130mph.