O2 sensors
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Senior User
Joined: Apr 2005
Posts: 213
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From: Port Coquitlam, BC Canada
O2 sensors
I have a question, I had a guy use a ford o2 sensor to set up my car to pass aircare, my car does not have an 02 sensor, it is a mercury and it is still a carb.
My question is I have aquired my own four wire sensor from a ford, and am wondering which wires to hook the meter to, to be able to read the output so I know how it is running now, and so I can use it to adjust it before the next aircare trip.
My question is I have aquired my own four wire sensor from a ford, and am wondering which wires to hook the meter to, to be able to read the output so I know how it is running now, and so I can use it to adjust it before the next aircare trip.
Laughing Gas
Joined: Jul 2004
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I suspect that he was probably using a wideband O2 sensor. A standard O2 sensor has very limited use in tuning a vehicle since it can't reliably make a/f measurements more than about +/- .5 from 14.7:1. Also, to make reliable and repeatable readings a bung needs to be welded into the exhaust somewhere just downstream of the manifold(s).
You could buy one of those cheap Autometer a/f gauges, but its only going to be of any use at part throttle cruise and idle. If you use enough throttle to activate the enrichment circuit its just going to read full rich and when you let off the gas it'll probably go full lean. Ideally for best emissions it should read in the stoichometric range at part throttle with a light to moderate load on the engine. This is the range at which emissions tests take place.
To answer your question, there are probably two white or possibly gray wire that are for the heater and then a green or purple wire that is the signal output. The fourth black wire is the sensor ground.
You could buy one of those cheap Autometer a/f gauges, but its only going to be of any use at part throttle cruise and idle. If you use enough throttle to activate the enrichment circuit its just going to read full rich and when you let off the gas it'll probably go full lean. Ideally for best emissions it should read in the stoichometric range at part throttle with a light to moderate load on the engine. This is the range at which emissions tests take place.
To answer your question, there are probably two white or possibly gray wire that are for the heater and then a green or purple wire that is the signal output. The fourth black wire is the sensor ground.
Posting Guru
Joined: Jun 2001
Posts: 1,236
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From: Vancouver Island
Table of how various 02 sensors are wired:
http://www.thegebharts.com/o2sens.html
Bosch says: "All Bosch 4-wire sensors have a black wire for the signal, a gray wire for ground and 2 white wires for the heater. Note: the wire colors and functions on non-Bosch sensors are not necessarily the same as on Bosch sensors."
http://www.boschusa.com/AutoParts/FAQs/OxygenSensors/
Some info on wideband sensors... it looks like it isn't trivial to hook one up; they use a DSP to do the figgerin' and controlling, and the whole shebang needs to be calibrated:
http://www.megasquirt.info/PWC/
The wideband sensors themselves aren't expensive (see the where to buy page).
Kits for wideband sensors: http://wbo2.com/
Narrowband sensors look easier: you can pretty much figure out the schematic from the picture of the circuit board: http://autospeed.drive.com.au/cms/A_...popularArticle
http://autospeed.drive.com.au/cms/A_2191/article.html
http://yarchive.net/car/oxygen_sensor.html
plans for an LM3914 display: http://nwerdt.com/how-to/electrical/...el_gauge_2.htm
http://www.redline.lt/magazine/spec-.../article/17/1/
Info on 02 sensors for the Megasquirt EFI system:
http://www.megasquirt.info/v22manual/mwire.htm#ego
http://www.thegebharts.com/o2sens.html
Bosch says: "All Bosch 4-wire sensors have a black wire for the signal, a gray wire for ground and 2 white wires for the heater. Note: the wire colors and functions on non-Bosch sensors are not necessarily the same as on Bosch sensors."
http://www.boschusa.com/AutoParts/FAQs/OxygenSensors/
Some info on wideband sensors... it looks like it isn't trivial to hook one up; they use a DSP to do the figgerin' and controlling, and the whole shebang needs to be calibrated:
http://www.megasquirt.info/PWC/
The wideband sensors themselves aren't expensive (see the where to buy page).
Kits for wideband sensors: http://wbo2.com/
Narrowband sensors look easier: you can pretty much figure out the schematic from the picture of the circuit board: http://autospeed.drive.com.au/cms/A_...popularArticle
http://autospeed.drive.com.au/cms/A_2191/article.html
http://yarchive.net/car/oxygen_sensor.html
plans for an LM3914 display: http://nwerdt.com/how-to/electrical/...el_gauge_2.htm
http://www.redline.lt/magazine/spec-.../article/17/1/
Info on 02 sensors for the Megasquirt EFI system:
http://www.megasquirt.info/v22manual/mwire.htm#ego
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Senior User
Joined: Apr 2005
Posts: 213
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From: Port Coquitlam, BC Canada
Well this is great guys, I had forgot as Bart99GT said that we welded the boss into the exhaust and made a hole so he could screw in the sensor from either a truck or van that he had and the values for the milivolts I think it was were on the notes he had from his automotive days when he worked for a propane company and did conversions for people and company vehicles.
When I was there a few years ago his exhaust analyzers were down, so he had a balance meter with lights that got him close then he hooked up the meter while under my vehicle then came up top and watched the meter while adjusting timing and things and then said it was as close as he could get it, and it passed aircare with no problem.
That was after I had taken it through before and failed, so I figure that I should be able to duplicate it, if I can find out what the readings should be.
I have since been back to aircare and not failed the way it was left from that time.
When I was there a few years ago his exhaust analyzers were down, so he had a balance meter with lights that got him close then he hooked up the meter while under my vehicle then came up top and watched the meter while adjusting timing and things and then said it was as close as he could get it, and it passed aircare with no problem.
That was after I had taken it through before and failed, so I figure that I should be able to duplicate it, if I can find out what the readings should be.
I have since been back to aircare and not failed the way it was left from that time.
