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Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 11:14 am
by classicdat
I have just purchased a second hand AutoGauge AFR Stepper Motor gauge, no wiring diagram or anything, pictures attached.
I powered it up, red to 12v and Black to ground, nothing else connected, and it lights up and the needle goes right around.
No matter what else I do that is all that happens, grey to sensor, violet to sensor, grey to 12v, nothing changes, still full rich is displayed.

Any ideas? Not much use currently.

Confession: Is fitted to a VT Commodore, Gen 3 5.7L in to the factory sensor, bit sophisticated for a 1200 on carbs!

First shot shows the 4 wires, Grey, Violet, Black and red

Re: Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 12:14 pm
by DJZ
I'm pretty sure one of the extra wires will be for connecting to the dash lights, I'd suspect it would be the purple one.

How many wires does the oxygen sensor have and do you know which wires are which? There are a couple of different types of O2 sensor but I'd think a Holden would use a standard style one.

I'd be careful about putting 12 volts on the wires as well, most O2 sensors are only 0 - 1V unless it's a wideband sensor, I think they might be 0 - 5V?

Re: Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 12:28 pm
by datsunboy
correct....narrowband is 0-1V, wideband is 0-5V
This will surely be a narrowband gauge, and designed to just receive a 0-1V signal from the factory wired O2 sensor.

Some factory sensors are heated, some are not.....both will be narrowband

Re: Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 12:37 pm
by classicdat
Thanx Guys, yeah only connected voltage to gauge. Car is running LPG so am using the wire they took the O2 signal off for that. But connecting it doesn't matter, still reads full rich.

Re: Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 12:43 pm
by datsunboy
I think that this is the instructions for your gauge.....or very similar.

So violet to dash lights.

the White (or grey in your case) will be the sensor wire.....and should be 0-1V only.

Wire it up like that, and start the car up for 5mins, and if it doesnt change then I'd take a guess that the gauge is poked

Re: Air Fuel Ratio Gauge Help

Posted: Wed Sep 28, 2011 12:48 pm
by classicdat
I fear you are right Dan. Thanx, but not really what I wanted to hear.

Re: Air Fuel Ratio Gauge Help

Posted: Sun Oct 02, 2011 10:29 pm
by 160jsss
you say it's running on lpg that will give you different readings ?