3 wire o2 sensor

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akchevrolet

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I was wondering the best way to wire the positive wire for tge heated o2 sensor.
 

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would this be good to use and find ignition powered fuse in fuse block

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bucket

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I ran mine off an empty IGN tap in the fuse box. I ran an inline fuse holder just to be safe. It was easier to do that than determine if there was already a fuse that ran that IGN tap.
 

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I ran mine off an empty IGN tap in the fuse box. I ran an inline fuse holder just to be safe. It was easier to do that than determine if there was already a fuse that ran that IGN tap.
I don’t know how much power a oxygen sensor pulls but wouldn’t I engine running power be best or is it turn off after it’s temp/negligible power draw
 

bucket

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I don’t know how much power a oxygen sensor pulls but wouldn’t I engine running power be best or is it turn off after it’s temp/negligible power draw

It only gets power when the ignition is on, which is how the O2 heater is designed to work. There's no draw when the truck is off.
 

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It only gets power when the ignition is on, which is how the O2 heater is designed to work. There's no draw when the truck is off.
Yes but how much heat we talking, electric choke lol
 

bucket

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Yes but how much heat we talking, electric choke lol

I don't recall off hand. It's a non-issue though, it's not designed to cycle on and off as needed. Whether or not the engine is running, it doesn't care. It's just designed to be on so that it can get a proper reading without relying on exhaust heat to warm it up.
 

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I don't recall off hand. It's a non-issue though, it's not designed to cycle on and off as needed. Whether or not the engine is running, it doesn't care. It's just designed to be on so that it can get a proper reading without relying on exhaust heat to warm it up.
oh must be insignificant then most newer cars have 4+

mine have 2
my dads van(e250) had 6, dont know where or how but rip
 

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I have a heated O2 sensor on my 1978 MG-B, converted to two SU carbs from a single barrel whatever it was carb.
I wanted to be able to monitor the air/fuel ratio without having to pull over every ten miles and pulling plugs. The sensor is hooked to a gauge in the cabin.
Last trip out, right after installing the gauge, got 50 MPG but thought I was going to scorch pistons coming back home from Billings. I dont remember the numbers but it was lean, way beyond comfortable lean. Had to back out of the throttle through the hills to keep it from going to the burn stage.
 

MrMarty51

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Oh yeah, the O2 sensor is a three wire and the carb I got away from was a one barrel Zenith.
I got the dual SU setup from an older MG that I parted out.
 

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I have a heated O2 sensor on my 1978 MG-B, converted to two SU carbs from a single barrel whatever it was carb.
I wanted to be able to monitor the air/fuel ratio without having to pull over every ten miles and pulling plugs. The sensor is hooked to a gauge in the cabin.
Last trip out, right after installing the gauge, got 50 MPG but thought I was going to scorch pistons coming back home from Billings. I dont remember the numbers but it was lean, way beyond comfortable lean. Had to back out of the throttle through the hills to keep it from going to the burn stage.
Burn means you have less mass, less mass is the key to efficiency. Clearly we need our engines to be lean as possible at every stage so we can produce nice clean combustion and wow that is one red catalytic converter, shall we observed the temperature precious metals become liquid
 

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Do you just ground it to the frame
 

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Do you just ground it to the frame
You can ground it anywhere you want as long as it's a good ground.Ground is indiscriminate ,it all goes back to the battery negative.
 

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Most O2 sensor heaters draw 4 - 6 amps some as high as 7amps. If it were me I'd fuse it at 10amps, but you could try a 7.5 and move up to a 10 amp if you need it. It is acceptable to ground the heater to a good ground, but it does really need to be a good ground, not a good enough ground like you can get away with somethings. At the shop when wiring an O2 sensor I decide if the frame or body will be better, then solder and shrink wrap the ground wire to an eyelet. Grind a spot of bare metal, attach the eyelet with a bolt and paint over to seal.
 

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