o2 power supply

[Stringer]

Hi All
just got my o2 sensor welded in and thought it might be a good time to check that there was power going to it. Du'er !!!
What a ))_)_(9wit I am ! Yes, you've guessed it, when i tested the power supply line (a heavyweight green cable), with the ignition on, there was naddah coming out of it.

is there an obvious place to go now? No, i dont mean, a councelling centre in south london who can talk to you about your troubled childhood. I mean, should i be looking somewhere obvious under the bonnet for a broken cable, missing relay etc etc
Or more to the point, are there any risks me just powering it directly from any nearby supply? Radio, for example.

thanks to all those who usually help me. You know who you are

M in beirut

 

[grober]

IRRC for cars that age power comes from the fuel pump relay. I would check that connection supply again with the engine running since power to the fuel pumps require an "engine running" signal to continue to supply 12volts.

 

[Stringer]

hi graeme
that was the second thing i checked, I fired it up and checked again and still nothing
M

 

[grober]

Might be a wiring continuity problem then- in particular - anywhere the wiring goes thro any grommets or any vulnerable connectors? there may also be an inline fuse somewhere. Fuel pump relay may still be faulty

 

[Stringer]

would a faulty fuel pump relay effect the engine's performance though? All i can see is the wires going into the engine bay through the grommet

what about connecting it with a power supply? (the o2 sensor, i mean)

 

[Bernie C]

Hi
Make sure the engine is warmed up as I believe the car runs "open loop" until warm - then it looks at the O2 sensor
Worth a try!!!

 

[Stratman]

The 02 sensor may have a heater in it, to get it up to temperature as quickly as possible. This will obviously need powering.
If there isn't a heater, the wire is probably just the signal wire from the sensor. This will only have a voltage on it when connected and working.

All about lambda sensors

 

[Stringer]

aahhh that might explain why the cable was so heavy duty - like a ten amp piece of wire. But even if that wasn't working, it would still heat up in time, right? I mean, whats the ultimate way of testing whether the o2 sensor is actually working?

 

[Stratman]

aahhh that might explain why the cable was so heavy duty - like a ten amp piece of wire. But even if that wasn't working, it would still heat up in time, right? I mean, whats the ultimate way of testing whether the o2 sensor is actually working?

The article I linked has a 'Lambda Sensor Checks' section about two thirds of the way down. You'll need at least a voltmeter.

 

[Stringer]

this was really useful, thanks a lot
m