Lambda Sensors

[Sando]

These can be quite expensive, so I thought this looked a bargain.
- A guy selling Lamda Sensors for £29.

Any use to anyone?

ebay (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2454634835&category=30921)

cheers
Rob:cool:

[roger001]

Check out

http://www.buypartsby.co.uk/lambda_sensors.php

you can practicaly buy new ones for that price.

[Sando]

you can practicaly buy new ones for that price.
:D :D

and I thought they were over £100.......
Doh!

For us boys that don't have them from the factory, what about using them for tuning?
Anyone know how to rig up a reader? I believe it's a voltage they give out?

Rob:cool:

[roger001]

[QUOTE
and I thought they were over £100.......[/QUOTE]

They are if you buy branded ones e.g. bosch. but seeing as I am fitting one to a home made exhaust and wiring loom I thought a universal one would be worth trying.

[CorseChris]

Originally posted by Sando
you can practicaly buy new ones for that price.
:D :D

and I thought they were over £100.......
Doh!

For us boys that don't have them from the factory, what about using them for tuning?
Anyone know how to rig up a reader? I believe it's a voltage they give out?

Rob:cool:

Rob, I have used a Bosch ex- Alfa 155 pattern lambda probe for mixture checking before. Made myself a wee box that indicates the lambda for about £20. Demon Tweeks will sell you one for about £120 if you'd rather......

If you have an interest I'll post the circuit diagrams. My unit works with any 0-1v analogue output Lambda (which is pretty much every one fitted to Alfa engines) Typically available for about £30 for a pattern job. Doesn't matter if they are heated or not really, it's just better to get one with a heater if you can as it allows way more freedom about where you put it in the exhaust.

[Sando]

Hi Chris
Yes I'd be interested to see the diagram and the parts required. It's a long time since I made anything like that, but may be a useful project for setting my mixture up accurately. I can soon weld a boss into the exhaust.

How do you know if the sensor is heated or not? is it the number of wires or do you just ask for one at the Lambda shop!? :D

Do you know what the 'wideband' term means.


Cheers
Rob:cool:

[chris.richard]

Mine has two heater wires and two sensor wires Presumably no heater = 2 wires.

[CorseChris]

Originally posted by chris.richard
Mine has two heater wires and two sensor wires Presumably no heater = 2 wires.

This is a pretty concise information page....

http://www.lambdasensor.com/main/mtypes.htm

A wideband sensor has a much more linear rate of change of reading as compared to the type more typically used in production cars (they can have pretty dramatic output swing for a very small change of oxygen content around stoichiometry in the exhaust). Reasoning goes that it's hard to tune something when the lean/rich indicator swings wildly around the centre value. It's a fair point! Using a 'narrow band' sensor can be frustrating as a small change appears to make a dramatic difference (ask me how I know....). It's OK as a confidence indicator though. I think it would be accurate to say that a wideband is far better for tuning work but they tend to be rather more expensive.... last time I heard figures quoted they were around the £1000 mark. Prices have no doubt dropped a bit since then though.

Anyhoo, I'll dig out my cheapskate gauge circuits.

[CorseChris]

Originally posted by CorseChris




Anyhoo, I'll dig out my cheapskate gauge circuits.


....circuit diagram can be found in the gallery...... I don't claim design rights - it's probably a 4th hand re-work and it's a pretty generic use of the LED driver chips anyway so isn't likely to upset anyone....

It worked just fine for me as-is. The pin numbering around the op-amp shows the connections for both amps in a package - don't try connecting them up that way, you only need use one :)

[Sando]

Cheers Chris
another job to add to the list !

looks straight forward enough, do you end up with three rows of LEDs then?
Rob

[CorseChris]

I just stacked up a bunch of discrete rectangular LEDS, colours to reflect what I thought was pertinent - green around rich side of stoic, tending to yellow as it got V rich, yellow on slightly lean, red on lean. I've made a couple before now and have used small rectangular as well as large, bright, round ones. Whatever suits your needs really.

Don't be put off if it seems to dart about from rich to lean - usually means it's about spot on. As I said, the more common sensors are very sensitive around the centre point and quickly reach a point where they are extemely insensitive so it takes a bit of getting used to. Despite this, it can still be used to show a long-term error or transient problem that might otherwise be tricky to catch. The transfer characterisitcs are a very pronounced S shape curve. Some older ECUs spent all their time swinging from rich to lean so the signal on the Lambda was pretty much a square wave - as long as the duty cycle was about 50% it had to be working right.

If you are really keen, you could always go for a mapped ECU with logging. I'm about to get one of the new Emerald M3DK units for our Westfield. They do all manner of logging, triggered by whatever you fancy. Very handy for the tinkerers among us.....