Lambda and Diy Air Fuel ratios

[Gassed'58]

I've been looking into making a home made air fuel meter and have come across this on the web which gives a good basis

http://www.redline.lt/magazine/spec-featur...e/article/17/1/

I did find a drawing using two of these linked together for even more leds in the display, cannot find it at the minute. Anyway,

I'm running LPG on a 2.25 series 2 with a soon to be added Megajolt and think that this sort of disply in the cab would give me some usefull info to set things up / give piece of mind without going to garages or using rolling roads for set up.

I read that a wideband Lambda sensor would be the best but having spent loads recently I was wondering if these sensors are available to to robbed from a car in a scrapyard ? If so, anyone know what cars they are fitted to ?

If not, anyone done this with a narrowband sensor ? I'd be glad to hearyour experiences.

Any advice generally is most welcome. Thanks.

[Diff]

I've been looking into making a home made air fuel meter and have come across this on the web which gives a good basis

http://www.redline.lt/magazine/spec-featur...e/article/17/1/

I did find a drawing using two of these linked together for even more leds in the display, cannot find it at the minute. Anyway,

I'm running LPG on a 2.25 series 2 with a soon to be added Megajolt and think that this sort of disply in the cab would give me some usefull info to set things up / give piece of mind without going to garages or using rolling roads for set up.

I read that a wideband Lambda sensor would be the best but having spent loads recently I was wondering if these sensors are available to to robbed from a car in a scrapyard ? If so, anyone know what cars they are fitted to ?

If not, anyone done this with a narrowband sensor ? I'd be glad to hearyour experiences.

Any advice generally is most welcome. Thanks.

I have a 2.5 petrol on LPG and I use a digital volt meter to check the mixture. The narrow band lambda probe is fitted in a boss which I welded into the downpipe near the manifold. I use a probe with a heater (mine is a four wire, but can be a three wire), the multimeter connects to the signal wires.

I set the digital meter to the 0-2 volt scale, and it works fine, I can check the mixtures while driving with some extended wires round the bonnet and door seal.

A narrow band sensor only gives a simple reading as it isn't linear in operation. If you want something permanent, you can use LEDs or buy a 0-1v panel meter for about £15.

Regards,

Diff

I find it very usefull.

[FridgeFreezer]

As above, a voltmeter is the cheap and easy way although the circuit you link to works fine too, I use the same circuit for my temperature & battery gauges.

(This was a very prototype lashup)

A wideband sensor requires a special controller so you are pretty much bound to buying the full setup anyway, Innovate LC-1 etc. are decent value (in fact you would struggle to buy just the sensor for the prices they sell the kit for sometimes!). Narrowband sensors are cheap, readily available and TBH if you're on carbs they're about as accurate as you need to be anyway.

[Dave W]

Rather than using Megajolt, you could use Megasquirt and hook the lambda up to that. That way you get an easy way to display and log your AFR using the standard software.

[Gassed'58]

Ok, thats cleared some of the wool out of my head, thanks. Looks like a narrow band sensor is the way for me then. The scrappy will hopefully liberate something today that I can use as a mock up and I'll probably use a meter for a while untill I get round to ordering up something a bit more permanent. Not sure about leds vs panel meter yet, will have a look online. Dave W, megajolt already bought thanks anyway.