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Re: Installing Fuel/Oxygen Gauge QUESTION Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Sat, 28 Mar 2009 18:32:23
In Reply to: Installing Fuel/Oxygen Gauge QUESTION, Daven  [Profile/Gallery]
, Sat, 28 Mar 2009 14:33:18
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First - what year and model?
The sensor signal connects to the fuel injection computer. That's the LH computer for earlier cars, Trionic for later cars.
The O2 sensor has three or four wires. For the three wire setup, two wires are the same color, and those drive the sensor heater. Those AREN'T the signal wire. The wire the others aren't is the signal wire. Typically the two white wires are the heater, the black is the signal. For a four wire sensor, the two whites are the heater, black is the sensor, grey is the signal return. That's at the sensor; after it goes through a connector, wire colors can change.
I'm surprised at a 16 gauge wire. The signal wire on a O2 sensor is typically 20 gauge; 16 is pretty hefty. Yes, you can always run a thicker wire, but 14 gauge is the type of wire you'd use to drive a 30 amp radiator fan, not the O2 sensor. The O2 sensor signal is very high impedance - that means very little current flows in the circuit. You need thick wire for high current circuits. a 20 gauge stranded wire would be just fine, and would be A LOT easier to route that 14 gauge - that's structural.
Yes, you can just splice at the O2 sensor. The reason they say after the plug is that the O2 sensor typically has a connector on it, to connect to the car wiring harness. If you replace the O2 sensor, and you simply disconnect it at the plug - you don't have to go all the way back into the wiring harness to the fuel injection computer. If you splice in right at the O2 sensor, if you replace the sensor, you'll need to re-splice into the new sensor. Not a horrible thing, just not as neat and clean as splicing into the harness. If I were you, I would splice in right at the sensor. That way, if you mess it up or it turns out your mixture gauge is a bust, you haven't hacked up the car's wiring harness.
Again, depending on the year of the car, you might have 2 O2 sensors. You want to make sure you connect to the O2 sensor that is right by the exhaust manifold, typically on the down pipe. You don't want to connect to the O2 sensor after the catalytic converter (if you car has an O2 sensor after the cat.)
But a 20 gauge piece of wire is just fine. Electrically, it can even be smaller, but it's nice to have a wire with some heft in the vibration environment of a car. Just make sure you route the wire away from hot bits.
posted by 76.243.123...
, Sat, 28 Mar 2009 14:33:18, Sat, 28 Mar 2009 18:32:23 <-- Viewing This Message, Sun, 29 Mar 2009 16:05:03, Mon, 30 Mar 2009 06:02:27
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