Deaf and Dumb Xantia

tim leech · Post by **tim leech** » 05 Sep 2010, 20:30

DickieG wrote:Lexia will search for the relevant software for whatever it detects with regard to ECU's and the attached wiring loom, now bear in mind that the additional earth on pin 25 should only be used on L6A engines so when Lexia searches it detects the additional earth and then applies software relevant to L6A but that software is not compatible for a 1.8 with a cat (LFZ) hence Lexia cannot then communicate with the ECU.

Citroën established that the looms fitted to a batch of these car's was wrong and issued an "Info rapid" (service bulletin) so why look a gift horse in the mouth and waste further time and money looking for the end of a rainbow when numerous items have already been exchanged without success when a brief trial of disconnecting pin 25 on the ECU may sort it, why try and complicate matters further? Am I missing something here?

Im happy to try that Richard, we had this car from new and it was always frugal and peppy when new, sadly now its quite the opposite.

DickieG · Post by **DickieG** » 05 Sep 2010, 20:35

tim leech wrote:Im happy to try that Richard, we had this car from new and it was always frugal and peppy when new, sadly now its quite the opposite.

In the absence of any better idea's I know what I would be doing Tim, what have you got to lose? The alternative is to continue scratching around in hope of stumbling upon something whilst knowing about a free/easy suggestion may work, no brainer for me.

tim leech · Post by **tim leech** » 05 Sep 2010, 20:42

Bear in mind I'm no mechanic how do I identify pin 25 and disconnect it without doing any damage

Thanks.

DickieG · Post by **DickieG** » 05 Sep 2010, 20:59

tim leech wrote:Bear in mind I'm no mechanic how do I identify pin 25 and disconnect it without doing any damage

Thanks.

IIRC take a very close look at the plastic surrounding the pins and you'll see a number moulded into the plastic relating to each pin number. If you use a small watchmakers screwdriver you should be able to unclip the relevant wire from the multiplug. I'll have a look at the breakout harnesses I have and work it out for you tomorrow if necessary. Alternatively the Info Rapid mentions disconnecting the other end of the additional earth wire where its earthed on the right front wheel arch but that may take a little more finding/doing than unclipping the wire from the multiplug.

tim leech · Post by **tim leech** » 05 Sep 2010, 21:02

OK Richard, maybe I will leave it until I getto stratford and then buy you a cuppa and leave you the keys!

DickieG · Post by **DickieG** » 05 Sep 2010, 21:06

tim leech wrote:OK Richard, maybe I will leave it until I getto stratford and then buy you a cuppa and leave you the keys!

Yeah fine no worries.

tim leech · Post by **tim leech** » 12 Sep 2010, 20:42

well after all that it seems to be a duff lambda probe, which I guess is an easy fix, now looking about on ebay and stuff theres lots to choose from but most are just generic "cut to fit" types which is what we fitted before and it doesn't work.

How many wires should mine have and does anyone know the part number?

The bosch number is 0258003239

Deanxm · Post by **Deanxm** » 12 Sep 2010, 20:52

Depends on what type of sensor but i would imagine its a 4 wire heated type, one + and - for the heated tip and a + feed to the o/s senor itelf and a signal return to the ecu, any 4 wire will fit you just pay extra (a lot) for the plug/s on the end of the wire.
In fact i know someone who put one from an m reg golf onto a 07 Porche boxster and it works perfectly so dont bother paying out silly dealer money.

D

VertVega · Post by **VertVega** » 12 Sep 2010, 21:10

In mine there are four wires and connector is somewhere over the gearbox, towards firewall.
. White --> Heater
. White --> Heater
. Black --> Signal
. Gray --> Ground

DickieG · Post by **DickieG** » 12 Sep 2010, 21:15

Here's a useful link for Lamda sensors.

Post by **CitroJim** » 12 Sep 2010, 21:16

There's a little more to this story.

As said before the ECU was reporting itself to the Lexia as a L6B, the non-cat variant. We did indeed fond Pin 25 was earthed and after lifting this earth the ECU then reported itself as a LFZ cat ECU as it should.

It was then that the Lambda sensor fault became apparent and the K light duly illuminated.

The recorded fault was mixture adjustment out of limits. Live data on the Lexia showed the lambda output at a very fixed and constant 26mV. Disconnecting the lambda sensor allowed the voltage to float to around 400mV and the engine ran a bit better.

It is a heated type Dean and it is a replacement. It may be just that the replacement has been mis-wired and the heater element is connected to where the sensor should be and vicky-verky.

Can a lambda sensor die in the presence of the very rich mixture this car has been running for the past goodness knows how long?

I reckon a correctly wired new lambda sensor an a lLxia session to clear any resultant stored faults will have her running beautifully sweetly Tim...

Deanxm · Post by **Deanxm** » 12 Sep 2010, 21:29

yes Jim a rich mix will block the lambda sensor and because it compares atmospheric oxygen content with exhaust gas oxygen content to give a reading if it cant sample exhaust gas it will give a max reading at one end of the scale, probably richening the mix which i guess is what has happened then.
i remember this story now, very strange indeed!!!

D

tim leech · Post by **tim leech** » 12 Sep 2010, 21:29

Thanks for your help today Jim and Richard by the way! When I bought the car it had this running problem, the first thing I changed was the lambda prob as that was the general consensus which i got from a local factors.
It is/was a 4 wire one that had to be adapted to fit by someone (not his fault) who hasn't worked on anything else but VW's and did look rather baffled, it made no difference to the rich running and as Jim mentioned isn't doing anything so I imagine its been incorrect wired up and installed.

Post by **myglaren** » 12 Sep 2010, 21:51

Would a long term rich mixture also have potential damaging effects on the cat?

If the cat isn't functioning properly then the lambda sensor might well have a problem to report on.

Vicious circle.

tim leech · Post by **tim leech** » 12 Sep 2010, 22:15

myglaren wrote:Would a long term rich mixture also have potential damaging effects on the cat?

If the cat isn't functioning properly then the lambda sensor might well have a problem to report on.

Vicious circle.

The cat is quite new, (done less than 1000 miles) as that was changed as part of trying to cure it, so hopefully it wont be too buggered!

Lets see what a correct new lambda shows up!