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Author Topic: Using an Artuino to drive an Automotive Lambda AFR display/ controller  (Read 872 times)
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Dear Colleagues

As the  long suffering owner of a DIY JAW wideband lambda sensor controller for my carburetored 1978 Austin Mini, I got around to thinking that the Arduino board could be used to do the same job but better? It would need to monitor and control the heating of the sensor dynamically as well as delivering the output from it as three LEDs YELLOW (rich) /GREEN (ok) /RED (lean) and a display of lambda / AFR





from  http://wbo2.com/lsu/lsuworks.htm for the system

Gives you a schematic of the setup, the heater circuit is about 1 amp, I don't really understand all the complexities

Any thoughts???? I am not a programmer but can build an engine from a box of bits!

This could be a useful project for any school involved in automotive projects as the source 5 wire lambda sensor is from a VW Golf and costs 30-40 UKP plus the cost of welding a mounting in the exhaust

NOTE I am not running an injection system from the AFR/Lambda output, simply monitoring the state of tune of a carburetor based system.

Regards

Dr B

Lambda sensor? see: http://en.wikipedia.org/wiki/Oxygen_sensor
JAW?: http://www.flickr.com/photos/johnbullas ... 444437107/
« Last Edit: February 15, 2013, 06:17:22 am by drjohnbullas » Logged

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As an update, here is a link to the best datasheet I can find for the lambda sensors I have..... http://www.bosch-motorsport.de/en-US/literature/en-US/Lambda_Sensor_LSU_4.2_Datasheet_51_en_2779111435.pdf
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That looks like a good price for the lambda sensors - I pay double that for mine.

It looks as if the circuit is designed for purely analog control - is that correct? Only the new Due has true analog outputs. Perhaps for the heater control you could get away with PWM instead of an analog output?

I don't see where the lambda output is from that circuit, but if there's an analog output it would be simple enough to read that and switch the LEDs according to the value. However, if the existing driver has an analog output then it would be possible to have that directly trigger an LED bar or a voltmeter masquerading as a lambda gauge.

Are you envisaging using it for any form of closed tune fuel control? I've heard of people doing that by using float chamber vacuum to tweak the fueling, although I've never done that myself.
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