Bongo Fury

Has anyone spliced in a (+) wire from the lambda sensor (+) output to a voltmeter to monitor the correct operation of the sensor? http://www.lambdasensor.com/main/mtesting.htm and http://www.lambdasensor.com/main/mtypes.htm these pages suggest a voltage oscillating between 0.1 and 0.9 volts should be measurable (concept is below, voltages shown are wrong!)



Merry Christmas

Dr B

the polarity of the lambda seems pretty simple to determine

You need to use an oscilloscope really because a DVM doesn't really update quickly enough. There are gauges that simply average the signal over a period of time, I've never found them very useful.

I'll give the DVM a try as a fault should manifest itself as a sustained high or low, the DVM might give an average so that would be good

OK

I connected a test wire to each of the two wires of the lambda (white and blue) I connected each in turn to my D.V.M. (+) and the (-) to the chassis earth... engine running never got more than 30-50 mV though the reading changes with r.p.m. this could be down to charging up/drain etc..

Will try to monitor the voltage during a drive tomorrow but running cold should be excess fuel to begin with and as Zirconia sensors should swing from app 0.2v to 0.8v and back around once per second, getting the square root of f**k all doesn't bode well....... will double check my earth as well....



I have 2 spare sensors so will have fun....

You won't get a proper reading until the engine is warm enough to go into closed loop operation. You also need to be careful that the DVM isn't loading the ECU input as that will reduce the measured voltage. Its usually a 1M input impedance so if you have a 1M DVM then you will introduce an error into the reading.

I posted a video of the display on my DVM now I have fitted the new replacement lambda (black not blue signal wire - white earth/ground http://tinyurl.com/jwyd748 all wire joints are soldered and heat shrinked... YES the voltage is changing very quickly BUT it is changing (before it was hardly moving) and looks to be in the right ball park.....



.... my neighbour and Bongonaut Nick R will have an oscilloscope or I will risk 20 quid on ebay for one of these: http://tinyurl.com/ltkjxm5 to see if I get the classic readout as shown above... you can buy cans of gas of a known lambda value for checking but that would not help for this type as it is not self heating and needs to be in the hot exhaust near to the manifold to work properly

My other AFR/lambda setup has a self heating probe with FIVE wires and it is placed further down the system- see here: http://tinyurl.com/nfvk9f3 )

GreenBongo wrote:You won't get a proper reading until the engine is warm enough to go into closed loop operation. You also need to be careful that the DVM isn't loading the ECU input as that will reduce the measured voltage. Its usually a 1M input impedance so if you have a 1M DVM then you will introduce an error into the reading.

It looks like its flicking up to 2.2Volts which indicates a possible problem. What is the open circuit voltage from the DMM?

If you use a USB interface only use it with a battery powered device - never with a laptop plugged into the mains.

Here is what the old lambda was doing (according to my less than ideal DVM): http://youtu.be/jm1lPmwGCCA

I finally got some time with the lambda sensor connected
http://www.flickr.com/photos/johnbullas/11842997725/

The output seems to confirm the fact I am getting a reasonable
response from the lambda probe



Sadly the oscilloscope could not plot the time series I was looking for BUT the cycle seems good

That looks very wrong, I suspect that you have the 'scope input AC coupled - it should be DC coupled.

It was DC coupled, will check that we were not measuring the wrong thing!

Dr B

Pages 05 to 14 for this document https://www.academia.edu/5691570/Troubl ... da_Sensors are a good read about Lambdas, sadly the Mazda Bongo is not listed! Will give them a call!