Lambda sensor connector melted

[plipton]

Hi All,

My front lamda sensor connector must have been sitting on the turbo as it's completely melted. I have a new sensor and a replacement plug/socket but no idea which wires connect where.

I can see from the new sensor which wire goes to which pin on the plug, but as all 4 loom wires are white (very sensible!) I have no idea which is which.

Can anyone help with this? What voltages should I expect to see on each of the 4 white wires. What are they for etc?

Cheers
Rick

[gadgeroonie]

well two wires will be the heater and the other two the voltage signal

i suggest you buzz out which wires have continuity and then find out which ytwo belong in pairs

then add 12v and see which two heat the sensor up

hope this helps

[plipton]

gadgeroonie said:

well two wires will be the heater and the other two the voltage signal

i suggest you buzz out which wires have continuity and then find out which ytwo belong in pairs

then add 12v and see which two heat the sensor up

hope this helps

Thanks but it's the wires from the loom I need to trace (I don't want to damage the ECU)

Cheers

[gadgeroonie]

ahh - i suggest you unplug the ecu and buzz the wires from the pins on the ECU connector

has anyone on here got the wirng diagram for the Noble ?

[GreenV8S]

plipton said:

Thanks but it's the wires from the loom I need to trace (I don't want to damage the ECU)

I would have thought it was safe to power it up with the lambda sensor disconnected and see which leads are earthed and which one has a 12v supply.

[plipton]

Nearly there. I managed to trace where the black and the grey wires from the sensor connect. It's now a 50:50 on the 2 white wires (the plug is just a lump of charred plastic).

I'm amazed the car ran at all!

[JimNoble]

plipton said:

Nearly there. I managed to trace where the black and the grey wires from the sensor connect. It's now a 50:50 on the 2 white wires (the plug is just a lump of charred plastic).

Shouldn't matter *I think*. The other two will just be the heater, which doesn't care which direction the electrons shuffle past in...

plipton said:

I'm amazed the car ran at all!

Unless you're running closed loop (we're not AFAIK), the lambda output is only ever used at idle and with light throttle. Even then it's just used to average the mixture out over a narrow range arround stoich (ie 1.0 +/- a bit). Passing the MOT emissions test would be challenging though...

Jim

[mr noble]

Still not updated your profile from the westfield Jim!! No-one will know how cool you are having a Noble!!

[joust]

JimNoble said:

Unless you're running closed loop (we're not AFAIK), the lambda output is only ever used at idle and with light throttle. Even then it's just used to average the mixture out over a narrow range arround stoich (ie 1.0 +/- a bit). Passing the MOT emissions test would be challenging though...
Jim

A rough idle is one of the first signs of a lambda sensor gone.

[JimNoble]

mr noble said:

Still not updated your profile from the westfield Jim!! No-one will know how cool you are having a Noble!!

Sorted.

Surely the Golf made up for the missing cool factor though...?

JIm

Ps. Plipton - forgot to mention. Either use silver solder or just crimp the lambda sensor connector on. They usually have steel (I think?) wire which is a bitch to solder with the normal stuff...

[plipton]

JimNoble said:

Ps. Plipton - forgot to mention. Either use silver solder or just crimp the lambda sensor connector on. They usually have steel (I think?) wire which is a bitch to solder with the normal stuff...

Thanks for the tip.

Cheers
Plipton

[plipton]

Done!

Luckily, splicing into the engine bay loom was a doddle (the wires all took "poor man's solder" OK). What a pain getting the old lambda sensor out and even more so getting the new one in. I have no plans to do that again in a hurry!

Anyway, all runs fine again.