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Lambda sensor not working?


Eddy5

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Nearing the end of the build on a Summer Madness kit with the 1.8 Zetec and MBE EMS.

Looking at the data I'm getting back over Easimap 5 I believe the lambda sensor isn't working.

Lambda from LA System is always 1.05v, even after it's gone through the heating process and been running for a while.

I've checked the ECU config and it's set to be LA as opposed to LSEU. Anyone know the difference?

I've got pretty much every parameter logged so if more information is needed then I can supply.

I did try and get a scope trace, but just succeeded in ruining my fleece and burning my hand on the exhaust. There was defintely 12v being supplied to the heater, but I couldn't get a reading from the signal wires, which maybe because I couldn't get a good connection.

I'm going back next weekend with an alternative sensor to test.

I've checked the wiring at least 3 times as well and it's connected as follows

Sensor (Function) Vehicle Harness

White (Signal Ground) Purple/Black

Blue (Signal) Black/Red

Black x 2 (Heater) Red/Green and Black

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If you remove the sensor from the car (assuming its a 1V sensor) and connect a volt meter + to the signal output front the sensor and the - to the earth side of the sensor and heat with a blow torch you should get about 1v from the sensor if its working. Be careful though as you sound a bit like an accident waiting to happen  (sorry) ;)
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Do you have the lambda plug wired correctly?

Information from WF:

When replacing plug on sensor, looking on the back of the plug (cable entry) with plug latch at the top.

top left = Analogue earth

top right = Signal wire

bottom 2 = Heater wires (either way round)

HTH

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OK, thanks for the advice. I'll check again this weekend.

More things I've thought of, I'm getting an error code (256) and the engine behaviour doesn't change with or without the sensor connected.

1) Anyone got any idea if the values I'm seeing are correct?

2) What's the difference between the LA and LSEU type sensor config?

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Right, fixed it. I had the signal and signal ground the wrong way around

It's as Flappa says, looking at the back of the sensor plug (Where the wires go in) with the latch at the top (The actual one used to latch the plug together)

Pin on plug = Function = Colour on Sensor wiring -> Colour on engine loom

Top left = Signal Ground = White -> Black/Red on engine loom

Top right = Signal = Blue -> Purple/Black on engine loom

It doens't really matter which way the heater wires are but this is how they are on our car

Bottom right = Heater = Black -> Red/Green on engine loom

Bottom left = Heater = Black -> Black on engine loom

Hope this helps anyone else with the same problem :D

Typical values I found when it's working are

Lambda from LA system 0.91 to 1.05

Ri1 0 to 30R

Lambda Voltage at Pin 0 to 0.9v

Lambda from LA

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  • 2 weeks later...
OK, I may have got it wrong then. Apparently during the Pre-SVA check they had to swap 2 wires over. I don't understand this as it didn't work the other way around (Maybe bad connection). Apparently it's working now, I'll check and confirm what they've done when I'm next to the car again
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