Here's one for the technical minded - whilst having yet another tidy up in the garage yesterday, I found this in a box:

I assume (which is always a worry) its some sort of Air Fuel Ratio Gauge (whatever that does) there is no makers name anywhere on the gauge, so I can't really do much more research, the little research I have find is it needs a 'narrow-band 02 sensor' (if this is correct!)
The gauge has 3 wires coming off the gauge (red,blue,black) going to a plug.

1, What do I need to make it work
2, Where does the sensor go
3, And really what does it really do

That's a surprise - I'd have expected it'd want a wideband.



At a guess... Earth (black?), live (red?) and lambda (blue?) signal.

If you put +12v across black and red, it might fire into life, but won't give you a sensible reading without the lambda signal being present.

There's two basic lambda technologies - Zirconia (common), which ranges from 0.1 to 0.9v, and Titanium (rare), which ranges from 0 to 5.0v. Feed a low voltage (near-flat AA battery?) into the blue wire and earth, and see what happens.

Lambda sensors come in a variety of wiring, too - 1, 2, 3 or 4 wire.

1-wire has a signal wire and earths through the exhaust.
2-wire has an earth wire
3-wire adds a live for the heater (they don't work properly until they're hot)
4-wire adds a separate earth for the heater.

http://www.lambdasensor.com/main/mcolours1.htm



In the exhaust, as close to the head as possible. Ideally, on a 2cv, you'd want a pair of AFR meters, one for each side.



It tells you whether your engine is running rich or lean, and how much.

This is why a narrowband sensor surprises me - a narrowband sensor only works around a fairly small distance from stochiometry - 14.7:1 air:fuel. That's where you want the mixture to be for a cat to work effectively, but not for either maximum power or maximum economy. A wideband sensor will give a sensible reading over a much wider range of air:fuel.

Why do you want it? To help you get the fuelling right. Typically, you'd add one if you were putting on injection - Megasquirt or similar - and trying to set the fuelling map up. With carb, it'll help you get the jetting right.

Hi Toomany

blimey sounds a bit complicated!

with the narrowband sensor its only what I found so you are more than probably right about the wide band.

if I am reading it right, i need to put a 12v + across both the black and red wire to see if it lights up, or do I earth the black then + the red

as for what I need it for, the jetting on the race car is always a problem, so every little helps, it just where I place it it would have to go where the two pipes go into the 2-1

can I get and use a secondhand sensor from the breakers

I'd expect black to be earth, red +12v.



How far back in the system is that?



Lambas are (OK, medium-to-long-term) consumables, and usually a right bugger to remove, since they screw straight into the exhaust downpipe normally...
They're cheap anough, anyway, if all you need is a narrowband.
http://www.lambdasensor.com/main/muniversal.htm
<£30 for a generic...

Widebands are much, much more specialist bits of kit.
http://www.lambdasensor.com/main/mwide.htm

(I've not dealt with that site for lambdas, but I think they're the outfit I used to recon the Saab's injectors last year - in which case, I was very impressed with their service.)

Hi Toomany

connected the red to the + and black to earth, 3 off the little lights flickered then one light stayed on,

the length of the exhaust pipes to the red cross (see picture) is 120 cms (both the same)

I will contact Lamdasensor.com tomorrow and see what they say

cheers

Nice exhaust pipes, where did you get those?

Hi Grifftravel

its a Simpson race complete system - www.simpsonraceexhausts.com

Sounds like that's powered up, then... Tried feeding the blue wire ~1v and seeing what it says?



I'd hazard a guess that that's a bit far back.