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        General >> Problems >> changing a lamda sensor
        
(Message started by: mike.g on Oct 27^th, 2004, 3:21pm)

Title: changing a lamda sensor
Post by mike.g on Oct 27^th, 2004, 3:21pm

My car just failed emmisions.

I hooked up the OBD and found the lambda sensor virtually flatlining, a saved reading from 8 months ago shows more activity from the sensor but still erratic.

I think it needs changing before considering the CAT.

Can anyone tell me how to change it, I don't even know where to look but hoping its an easy DIY job.

I have 24hrs until the MOT retest expires!!

Title: Re: changing a lamda sensor
Post by Lee on Oct 27^th, 2004, 8:05pm

on my 12v they are just below the manifold should be in same place on yours, unpulg it, then undo nut then put new one on do up nut repulg, jobs done and it is easy coz i'm really thick when it comes to working on the car.
also i got sensors from a mondeo in scrap yard as long as it's got same amount of wires no worries (well they worked on mine :-/ )

Title: Re: changing a lamda sensor
Post by mike.g on Oct 27^th, 2004, 8:21pm

thanks,

is that from working under the car or from above.

Also are the universal lamda sensors just as good as the ones that come already with plugs.

I'm a bit worried it might lead to incompatability or problems re-wiring the old plug onto a new sensor.

Title: Re: changing a lamda sensor
Post by scorpio_man on Oct 27^th, 2004, 9:34pm

hi there

even with ford sensors you need to cut the wiring as they only have the rear (not on the 2.3) sensors now, if i remember correctly.

i changed mine not that long ago. you need to remove the heat shield. mark it up as you take it off as it turns into a jigsaw puzzle on refitting.

buy from http://www.cats-direct-shop.co.uk/lambda-sensors.php

i also bought the deep socket, made things easier. all work done from above (depends on where your lpg kit is).

Title: Re: changing a lamda sensor
Post by Dave Boulton on Oct 27^th, 2004, 10:19pm

Just a thought...

Do you know the sensor has failed? If not then it must be worth checking the wiring first - these things live in a really hostile environment and it's only a 1V circuit for the sensor signal. Got to be worth checking the connections before fitting a new one (if it's showing -ve voltage then it has failed - see the excellent writeup on the main site).

Cheers,
Dave

Title: Re: changing a lamda sensor
Post by Dave Boulton on Oct 27^th, 2004, 11:28pm

Mike,

Just another thought ;)

We are talking upstream sensor here aren't we? If not, then there's no emission related problem. If we are then you should probably be seeing other symptoms (like LOS?).

Dave

Title: Re: changing a lamda sensor
Post by scorpio_man on Oct 28^th, 2004, 8:08pm

hi there

the 2.3 doesn't have a rear sensor, for some reason :(a plug on the exhaust is in it's place. i always thought about fitting one from a 2.0. :-/

Title: Re: changing a lamda sensor
Post by mike.g on Oct 28^th, 2004, 8:50pm

Hello,

I was so sure it was a faulty sensor I changed it and even bought a special socket to remove it.

It was easy to change but I got no change on the OBD results, still flatlining.

I traced the signal wiring and the LPG system cuts into it and somewhere within the LPG boxes and wiring the signal is lost.

For the MOT I just reconnected the original signal wire (removing the LPG cut in) with a piece of wire. The OBD showed a fully functional O2 sensor (the same graph display I got 6 months ago) and the car passed fine.

Now I need to find out whats wrong with the LPG as it used to pass the O2 signal through to the scorpio ECU.

Also I now have a spare Ford lambda sensor and brand new special Lambda removing socket, which I will sell to pay for the new sensor.

Title: Re: changing a lamda sensor
Post by mike.g on Oct 28^th, 2004, 8:55pm

just to add,

my old sensor was fully functional it was just the wiring that was faulty,

I could have saved myself the money I payed for the universal sensor and socket if I had checked the wiring first ::)

Title: Re: changing a lamda sensor
Post by scorpio_man on Oct 28^th, 2004, 10:17pm

hi mike

did you have any work done on the lpg kit? could be the lambda sensor is switched off in the lpg ecu (as in mine). did you try and pass the mot on petrol? was/is the sensor working on the petrol with the lpg pick up in place?

i'm going down to autogas2000 in leeds next month for a rolling road/dyno setup. i'll be doing a write up for the site afterwards, hopefully with some tips. :)

Title: Re: changing a lamda sensor
Post by Eddie on Oct 29^th, 2004, 5:08am

It is a good idea to check wiring going into sensor body FIRST.
There is only PRIMARY insulation on the wires and they can be chafed through by the sharp edges.
It could be worth trying to fit a peice of heat shrink sleeving to a new sensor and try to get it into the housing a bit first.

eddie

Title: Re: changing a lamda sensor
Post by mike.g on Oct 29^th, 2004, 12:02pm

It failed the MOT miserably in petrol then i asked for it to go through on LPG, it got perfect results for the fast idle tests but failed on the CO at idle.

To get it through the MOT I used a wire to reconnect the lambda signal wire to the scorpio ECU that the LPG system tapped into. I didn't try putting it through with LPG as the lamda signal wouldn't be getting into the LPG ECU so it would probably have failed on idle as before.

So I put the car through in petrol, as if the LPG had never broken into the signal wire. It passed all test.

The thing is the car runs fine on LPG even with no lamda signal.

I don't know wether to have the LPG looked at and I wounder if the expense would result in a big enough improvement.

I get about 200miles on a tank of about 50litres, this hasn't really changed from when the sensor signal used to get routed properly about 6 months ago (I have an old OBD scan from that time).

Title: Re: changing a lamda sensor
Post by scorpio_man on Oct 29^th, 2004, 12:47pm

hi mike

i get about 150/160 miles on 44 litres (55 litre tank), which is about 18/19mpg @ 20/21 mph. my lambda sensor was only switched on once, but made the car run really rich (-25% dtc's)! before i get any work done, i want them to save the mapping to disk, then put in a new map. that way, if on the journey home, the consumption is away to pot, i can get the old map re-loaded.

andrew

you're still doing the high miles? i'll ask about any servicing that may be required when i'm down there.