ok i have a spare 3 wire o2 sensor and thinking about addding a o2 a/f ratio sensor to the datsun.
One wire is for the heater element, another for ground and the 3rd is the signal to the ecu.

As the datsun does not have an ecu, do i hook thi sdirectly to the guage or does it need an ecu for the correct sinals?

should work like a multi meter and just process voltage drops and spikes (reading lean to rich roughly) so there fore is a ecu needed at all?

not looking for the untimate in tuning efficiency but to give me an idea of rich/lean to some degree.

at least readings wont be as fluctuating as no ecu mapping to correct the a/f ratios in a carby car, so will be a progressive reading

looking at the jay car kit or possibly a guage.

You can buy an A/F guage that takes the O2 sensor input. No ECU needed.

Use a "wideband" sensor for acurracy otherwise it is just a relative signal (only guaranteed relative to crossing rich/lean boundary).

You would only use it briefly in carby engine or non-closed loop EFI. Then remove it and plug the hole. Otherwise it will foul. Some of the more expensive sensors might work better in this (heated, anti-foul sensors.

Put the sensor as close to the manifold outlet as you can get it. They need to be very hot to work correctly.

Mik

Haven't seen a wideband (at least not Bosch) that can be reliably run without a control unit, as all widebands I've heard about require specific heating routines and need to be able to constantly vary current/voltage with changes in AFR (that's how they get a wide band signal) - they are essentially a 'narrow band' with some extra computer smarts attached.

No need to grab a wideband to run a gauge, and unless your planning on some serious tuning I don't think the many 100's of $ would be justified.

A 'narrow band' or std 02 sensor is good enough to pass Euro IV emissions, should be good enough for a AFR gauge on the dash of the datto.

The closer to the manifold the better I agree...

I think the Bosch ones can take nearly 100,000ks before end of life - it's running really rich in petrol that kills them (not so sure about LPG though)

should be fine with lpg, saw some of the bosh 4 wires go 160,000kms before replacing

Cool, I hear you get a good deal on them anyway...

be sure to install the o2 sensor as close as possible to the ex manifold but without exceeding the maximum operation temp of the sensor.

Ive got a 4-wire nippon denso wide band sensor on the a15e ive built. Havnt run it yet though so cant give any other information. I dont have a gauge but the computer will let me know whats happening when its connected to the laptop

Quote:
Except that Euro emissions complient cars almost always run at stoich during normal drive cycle, and use the sensor to activate short and long term trims to keep it at stoich besides for WOT

The datto is at stoich almost never which means all the gauge will show is rich or lean and never give actual info that can be used to set up any form of tuning or mapping.

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Narrow band = non linear 0-1V
Wide band = Linear 0-5V

95% of wideband kits now use a gauge with all the hardware in the gauge and are small and compact such as AEM.

I run a PLX in my Datsun when I make jetting changes, I think maybe 5% of the time it actualy sits on stoich, never the less I think a $300au wideband is cheaper than rebuilding a motor, thus I use what works when making changes or trouble shooting

Yes, to control emissions they just read if it passes the stoich line. Normal sensors don't actually tell you an accurate A/F ratio. Wideband sensors are guaranteed for that.

That being said, it seems normal sensors can give you an indication of A/F ratio, while not very accurate, is good enough for testing or rich/lean indication.

Just an FYI, My bone stock A12 never once went leaner than 14.2, I tried to play with the jetting a tiny bit which resulted in slightly better AFR's but the car ran like rubbish, seems as they like to run slightly on the richer side of things. Anyone else notice with when using a wideband on a stock A-series?