Air/Fuel gauge/sensor questions

[Anonymous]

I'm thinking about installing an Air:Fuel meter so that I can better tune her. I understand that the O2 sensor needs to be installed in the exhaust (right?) and then wired to the gauge in the car. I was told that you drill a hole in the exhaust, weld in a fitting, then screw in the sensor. Sound right? Does it matter where in the exhaust the O2 sensor is installed? I'm running dual out headers with an H pipe down the line a bit right before the mufflers.

Is there an easier way to do this than cutting and welding, etc?

Can someone recommend a good combo (gauge and sensor)?

Thanks all.

 

[CobraSix]

All I really know is that the sensor needs to be mounted as close as reasonable to the cylinders for the best signal. Then there is the issue of 3 wire (un-heated) Versus 4 wire (heated) and narrow band versus wide band. If you were going to do it, get a heated wide band O2 sensor. Bosch ones from Autozone like that cost around $80 IIRC (or $150 to have someone install it).

Slade

 

[Anonymous]

Thanks Slade. what is the difference between heated and unheated (besides HEAT :roll: )? Since I'm using headers, I wouldn't want to install it in any one of the runners would I? Wouldn't that give a potentially one-cylinder biased reading? Unfortunately, the H pipe is quite a ways back, so I'll have to do it in one runner or in one of the two collectors (which could also yield a 3 cylinder biased, but that's more acceptable isn'y it?).

Can these things be epoxyed in place? Not the sensor itself, but the fitting. I have no welding ability or equipment.

Is the Bosch sensor universal in that I can add any gauge to it?

 

[Anonymous]

Heated sensors wouldn't make a difference in this application. They were developed for faster warm up emissions regulations. They may help in the way that if they're installed further downstream, you might get a more accurate reading, since o2 sensors require a lot of heat to work properly.

However, I found that most wideband sensors also happen to be multiwire heated models. A wideband is preferable to a regular sensor, as they are more accurate, and can show you a wider range of readings.

I'd suggest having the bung welded as close as possible to the header. With your dual outs, you may even consider having a bung welded into each of the pipes, run two cheaper sensors, and switch your wires back and forth while tuning each 'bank.' Gluing just won't cut it.

o2 sensors are pretty much universal, since they all feed out about the same range of voltage.

I'll be doing the same thing with mine in the spring. I'll be taking the cheap route though. Junkyard single wire sensor in the manifold, and whatever parts store meter I can find for under $30. I figure it should be good enough for my needs.

Jim

 

[Anonymous]

this the one?

http://www.napaonline.com/cgi-bin/ncomm ... menbr=5806

even says "downstream" on it. Must be heated then, eh?

Maybe I'm missing something. Autometer's A/F gauges all just say lean/stoich/rich. Don't I want something with a needle and numbers to be more precise? Do these gauges work with the wideband sensors or would the wideband sensor be worthless with this type of gauge?

 

[Anonymous]

The exhaust sensor fitting connection is also known as a "Bung"

Yes, I'm not kidding...it's a bung hole you are making in your exhaust.

cheers,
Steve-O

 

[Anonymous]

:roll:
I know, I laugh every time I say it too.

 

[mugsy]

HI!

I installed an Edlebrock A/F sensor in my '65 Mustang. I have the Cliffy one-out header, so I just put it in the down stream of the flange. I did this because I too was concerned that reading one cylinder doesn't tell the whole story. I purchased mine from Summit and with them being in Colubus, Ohio (boo, Go Blue!) is just one/two days ship via UPS.

I installed it right after my rebuild, when I put on a '77 250 head on a fresh 200 short block. Because this head has the larger carb hole, I used the YF carb that I pulled with the head. I was SHOCKED to find out the the "meter" went off the scale to the lean side at cruising speed. The meter has a series of LEDs that light, so its pretty easy to look at while driving. My car has a center console, so I put mine behind the console door.

I paid a muffler shop like $20 to weld in the bung. I had some other work done at the same time, so I might have gotten a deal because of the other work. The guy seemed real happy to do it, probably because it was something new, or he was tired of doing the same-old-same-old.

tanx,
Mugsy

 

[Anonymous]

I actually built one of the one with the LEDS that light up in sequence. They work alright for general tuning duties, as would a basic o2 sensor. A wideband and a quality meter would provide you with more accurate information, however.

It's hinged on how accurate you want to be.

Jim

(who knew my experience with EFI would come in handy some day?)

 

[Anonymous]

ok, so just so I'm straight. The wideband sensor is only used in conjunction with one of the digitla LED readout meters NOT with a little indash type gauge?

 

[mugsy]

To the best of my knowledge, the only commercially available wide band O2 sensor is from "Innovate", or something like that. It costs around $350 and has data logging ability and an bunch of other cool stuff.

Personally, I wanted one for a lot less and even called them to see if they offered one without the data logging function. They said, "No, they only had one type", so basically take it or leave it. So I bought the Edelbrock for about $125.

If I raced I suppose the data logging would be a great feature, but my personal feelings are to use the A/F with data logging for a one time set up a carb is a little like swatting flys with a sledgehammer.

tanx,
Mugsy

 

[Anonymous]

There are tons of wideband sensors available. Just type "wideband O2 sensor" on google, and you'll get tons of hits.

The type of gauge used for readings could be anything. A needle gauge, digital readout, LEDs, a little motorized robot giving you semaphore signals, it's all about what you want to see.

Like Mugsy said though, a wideband would probably be overkill. I can see an advantage to running a heated sensor a little further downstream in your application though.

Jim

 

[Anonymous]

Thanks guys. I went with a Stewart Warner gauge and a Bosch heated sensor. I hope to get the bung ( :roll: ) welded in this weekend so I can get to tuning.