Setting output mode for megasquirt use.

[paul f]

I have now got my Vems gauge set up and operating and want to install it to a megasquirt v3.
When powered up it shows a figure of 20.1 in free air , i have installed it in the exhaust of a car and put a meter on the output which seems to vary between 0.2 and .890v when running at a rich idle. I assume that it is set up in narrow band emulation mode. I called the supplier Mtech automotive who told me it was set to innovate 0-5v mode but is suspect they are incorrect. To adjust it i assume in need to connect the serial lead to a PC running the VEMS version of megatune?. Is this correct or do in need to run the firmware configerator? i would like to set it to give 0-5v output but the documentation shows modes are narrowband emulation or 1-2v 0r 0-3v.
Any help would be much appreciated.
Paul.

[rob@vems.co.uk]

As standard it is set up as either EGT output (0-5v) or narrow band.
The only way to be sure is to get the latest software release:
http://www.vems.co.uk/forum/index.php?topic=18.0

And setup the analog output using the description from the User Guide - note that the screen has changed.
http://www.phattransmissions.com/VEMSWB/UserGuide/README.html

The analog stuff has changed as theres now a method of mapping the output voltages to specific AFRs, its kind of explained here http://www.vems.hu/wiki/index.php?page=AfreshTiny%2FVoltageOutput but will need me to document it a little more clearly.

Please let us know how you get on.

[paul f]

i managed to get it set up eventually, it wouldnt comunicate with megatune to start with but eventually solved that by reflashing the firmware, set it to 5 in analog settings and now get a 0_5v output which i assume is linear and can be set as equivalent to innovate LC1?.I tried it on the car and it seems to be showing sensible readings so now just need to do some datalogs to find out .
Paul.

[paul f]

I temporarily fitted it to the car but am not sure that it is behaving correctly.I set the megasquirt to innovate LC1 default 0-5v and the gauge to output setting 5.
I have now noticed that in free air the output voltage is .100v and when i pass gas from a blowtorch over it or run the engine with a rich mixture the voltage increases to 5v. Is this not the reverse of the expected output?
It would still be near at lambda 1 but would have the opposite effect on the mixture to what is required if i allowed it to adjust the ECU.
Am i missing something?> is there another setting i have not got correct?
Paul.

[rob@vems.co.uk]

Free air is a tricky measurement because it means that the sensor is reading off its lambda scale and so the voltage has to be close to zero volts to stop the ECU from leaning out - so its not a true value.

I've not had a chance to play with the new output settings, and always used to use Analog Output settings=153 which gives 3v/lambda meaning:
0.8 lambda => 2.4V
1.0 lambda => 3.0V

It is possible to fine tune using this setting e.g. 152 will bring lambda 1 voltage down, 154 will take it up