O2 sensor

[jayw]

I may need to fit a Lambda Sensor to the car to run the Fuel:Air Gauge and the Nitrous Controller.

I assumed that the late 16v's (with CAT) had a simple fitting on the downpipe to take the sensor and i could simply cut the CAT off & joint the downpipe to my existing system.

But can i find the said downpipe? Can i Hell!

Does anyone know if they exist or are did they use some other method of fixing the o2 sensor. Even better if someone knows where i can get a good one!

Cheers, Jay.

[Vanny]

there are only two types of 02 sensor, heated and non. Heated are three wire non heated are two wire, other than that they ALL give the same 0 to 1v output and are all calibrated equally. Generic sensors from Demon Tweaks are £120 but they sell a standard 18mm boss for £7.50 ish which will take pretty much all Lambda sensors of any european built car (theres a small few with a 16mm boss, and anything with a 12mm boss is a EGT probe!).


So my plan is to go the scrappy and start hunting! Corsa's have there lambda sensors at the FRONT of the enigne right at the top just pas the manifold, making them a piece of cake to get out! Also a lot of Rovers have the engines in backwards so the lambda sensor is at the front of the car, giveing much easier access. If you want a Citroen one, then have a look for 1.8i Xantias but there probes are in the exhaust underneath the car which can create problems at scrappys!

[Mike E (uk)]

Ford Fiestas about L reg have a very easily removed sensor too.

To fit one in a non cat car, drill an hole in the exhaust pipe near the manifold, then weld a suitable nut over the hole.

Mike

[jayw]

I must have worded that wrong

I've no problem getting the sensor, they're widely available for as little as £22.00.

My problem is mounting it in the exhaust as our standard downpipe has no facility (mount) to fit the sensor into.

Hence my idea to use a later CAT type downpipe (assuming the sensor IS fitted to the downpipe and not somewhere else).

So, my questions are:

Where is the o2 sensor mounted on the late 16v's?

If on the downpipe, then does anyone know where i can get that downpipe?

Cheers

-- edit -- Mike, good idea! But would still need to know the correct placement, apparently these things are very precise.

[Anonymous]

drill a hole in the front pipe and weld an appropriate sized bolt in the hole then bolt the o2 sensor into that

[Vanny]

But would still need to know the correct placement, apparently these things are very precise.

the 'precision' is only in that the exhaust gasses passing over the sensor need to be hot enough to excite the compounds within, so if you where to get a heated sensor then you would over come this problem, other wise the sensor needs to be as close to the engine as realistically possible and before the CAT so as the BX16v's are all meant to have a 2 in one down pipe i should imagine that the correct positioning is approximately inline with the gearlever just at the point where the down pipe becomes a single and in front of the CAT but in the cat section of piping, and probably coming out towards the drivers side and up through a gromet to the ECU (though being french it could be anywhere!)

I have images of every citroen exhaust section upto the picasso so that will probably show where the boss is, will dig it out when i get home! This mean your changing ECU? Someing off the shelf or a M3.1 remap?

[jayw]

Nothing so bold as a new ECU.

It's simply because the Air:Fuel gauge i bought needs a Lambda signal to operate, as does the shut-down feature of the NOS controller.

As far as i can tell it doesn't need to be connected to the ECU as these can both operate independently.

Vanny, as our resident Tronics man:

I'm not sure which sensor to get, there are 1,2,3 & 4 wire jobbies:

1= signal
2= signal + earth
3= signal + heater + heater
4= signal + heater + heater + earth

Do you think i'll need the earth? And if i was to use a heated sensor how do you suppose i might operate the heater, is it simply 12v and could it be wired to come on with the ignition?

Cheers, Jay.

[Vanny]

if you dont feed it an earth then it will use the exhaust as an earth, which means it will earth through the manifold exmansion ring and all sorts of other gubbins, you also have gas running through the exhaust that will create some amount of charge so i think for your application you'll deffinately need an erth feed.

Heaters wouldn't go amiss if it was for an ECU in a cold climate, but i would assume that you'll be putting the NOS into a warm engine so its probably not worth it! (more wiring to go wrong!).

As for the heating feed you'd have to check the individual manufacturer spec sheet (can usually be found with crafty googling), but i think some of them are 10v, stupid i know but some of them just are!

The sensors when new are fairly robust, but like a light bulb once they have been used a few times (and get hold.cold.hot.cold) they become a little bit fragile hence they do break but not if they're treated with respect and not disturbed! (but no one seems to tell kwik fit this!) Otherwise, yeah its a switch on with ECU/Ignition jobbie through a relay is best, its possible to get the ML4.1 ECU to turn on things like that, but you could just run it from the key.

Only reason i know about these things is that this subject is my final year project some i'm a little but ahead of you on the reading up, pretty much every bit of info can be found online, asking the right people and the BOSCH Automotive bible which tells you EVERYTHING (from ESi to tread patterns!)

Where are you getting the sensors from? Every where i have looked have been best part of £100 and i need two for the bike!! Then again i have been looking mostly in the car sport worlds.

[jayw]

Cool, i'll just go for the 2 wire jobbie then.

Will probably also opt for the drilling/nut welding option for mounting.

Lambda sensors are here: http://www.buypartsby.co.uk/lambda_sensors.php

Used them before for my old 5 series & my daewoo.

GSF also do similar.

Cheers!

[Toddman]

Jay - CW had a weber air/fuel guage on his valver which Simran now has.
Daveat Emerald just drilled his downpipe and welded in a boss to accept the probe pretty much as Whitty suggests really.

If you are lucky Simran may still have that downpipe.

Cheers
Luke