Got this Dick smith kit for a narrow band AFR meter for $62 AU- I'm thinking that that price + a O2 sensor ($80-120) makes for some fairly cheap tuning to help with a rough tune for forced induction.

Kit KC 5300 down the bottom of this page

The kit is calibrated for a specific Bosch 02 sensorr- it will work on anything, but if you want reasonably accurate results you need to get this specific Bosch Zirconium one.
So I get the kit together & test it & it all looks good- I head to repco for the O2 sensor.......

$531 AUD


Awesome!

So now I need to try and find another sensor with a similar output.....

stoichiometric at 600 mV.

Does anyone have access to source of this type of info????

I got one to. Havent got it together cos i lost th instructions Grrrrrrr. Mine you can tune to a individual sensor they recomened one form the wreakers.

If its the Dick Smith one with an AFR readout and bargraph down the side, PM me and I'll photocopy them for you.

I have had a look around the net & the reccommendation from silicon chip magazine (the people who published the kit originally) is to use a late model commodore one, so I suppose that is a start...

A lot of O2 sensors hit stoichiometric @ 450 mV which is a fair difference to 600 mV. My concern is that if you adjust the offset to 450mV there wont be an appropriate level of adjustment ion the span control to get things accurate (i.e. you may be able to get it accurate in the lean side of the curve, but not the rich side, or vice versa)

The AFR only goes down to 11.8? I thought it would go lower than that - as cars running rich I've seen hit AFRs of 9!

Try finding out what vehicle uses the particular 02 sensor you are after, then go to somewhere other than repco as i find repco are the biggest rip off merchants.
Mechanical shops use them because the difference between trade and retail price is massive. This means there is a larger profit to be made.

Mildman, On a narrow band sensor, the sensor output hits a point at at 11.8 where it can no longer resolve differences in the AFR- this is the same for all commonly used O2 sensor because of the nonlinear output. the meter just comes up with an 'R' for rich.

Well I guess ideal AFR is around 12.5 - so you don't need to see it richer than 11.8 I suppose.

Hey Grunter,

Is this kit supposed to be accurate or just another rough tuning tool like those AFR guages?. How reliable is it supposed to be?

There are plenty of disclaimers in the pack that it shouldn't be used for tuning efi cars on dyno's.

Any narrow band sensor is going to struggle because of the shape of the output from the O2 sensor- it is inherantly a rough & dodgy system unless
a) the voltmeter that measures the sensor output has high resolution
b) the microchip that converts the voltmeter reading to AFR is calibrated for the sensor used.

so using the correct sensor (Bosch LSM11 0258104002 which is apparently a motorsport part- about $350 trade price) there is no reason why the output shouldn't be reliable, as long as the rest of the electronics in the kit is up to scratch in terms of resolution........ which is questionable. Without an equvalent sensor, all bets are off

For what I want, it needs to be good enough to tell AFR 12.5 from AFR 13.5, and if there are any lean spikes in the rev range so that I can get a basic tune to get me to a dyno shop. I am fairly confident that it will be able to do that, but I wouldnt trust it for any better resolution than 0.5-1 AFR unit

The main benefit is that most of the AFR guages are around $400, whereas this is $62 + the price of the O2 sensor you end up using.

Got iu & running- seems to work ok, but th calibration may be out. Was showing AFR of 14-14.4 under full throttle @6000rpm whereas on the dyno it was 13.6..... but the transition from rich to lean looks pretty similar through the range.

Need to get it back onto the dyno for a direct comparison- 14 is way too lean for WOT