Display Wideband on Dash - need help please

[FoxSTI]

Setup
I have configured an A/V input on my dash as follows:
Lambda with GAS AFR unit conversion ? (not sure how I did that to begin with in all honesty),

Ratiometric with the following values
0v = 7.23 AFR
5V = 22.39 AFR

I am using display creator to layout my information as wanted / needed.


The sensor is a Bosh sensor provided by innovate motorsport in their LC2 kit.
http://www.innovatemotorsports.com/products/lc2.php

Challenge / Issue:
C125 value reads slighting higher that directly from the Wideband Controller and higher than a factory installed wideband sensor (via ODB2)

What can I do to make the readings the same ? or better yet, to keep the C125 from rounding up.
I only want to display one decimal.

[FoxSTI]

So the Dash reads the 0v-5V signal slightly higher.
Is there a way to test my Dash properly interpreting values? I wan thinking of building a small circuit that will output 0V, 2.5V, 5V and different intervals to see what the problem is..

I wonder if my other sensors are reading wrong?
Has anyone else ran into something like this?

[Stephen Dean]

Are you saying that the Dash reads, for example, 2.5V, but the LC2 is only outputting 2.4V? or are you looking at the Lambda values and comparing them?

[the_bluester]

If you are using an AV input, is there any chance of a ground potential difference between the wideband and dash?

[FoxSTI]

Are you saying that the Dash reads, for example, 2.5V, but the LC2 is only outputting 2.4V? or are you looking at the Lambda values and comparing them?

So the LC2 has one output for a serial cable to connect to a pc for programing and logging. Through th is our put let's say I'm reading 14.67-14.7x

The lc2 also has a program able 0-5 volt output which I'm feeding to the C125. This is a single wire coming into an AV output.

So going back to LC2 reading 14.67, or 14.7 the C125 will read 14.8 -15.x

There is also a factory o2 sensor in the car, that sensor reads just like the wideband via the pc cable.

So for some reason it seem the c125 is reading a little higher.


I idea of a difference in the ground crossed my mind but both devices attach to the same harness I hade which is grounded at the cars battery.

I want to trouble shoot and test it honestly not where to start other than visually comparing values like i have.
If the was any othere sensor I probaly would not care much, but being a WB is needs to read and log accurately.

[the_bluester]

I am wondering about a tolerance issue as well. You have a double conversion going on there that is bound to introduce some amount of error. Firstly either it is converting a digitised reading to the analog output (Or converting a natural analog output to a digital reading internally for the serial display, either way gives room for errors) and then digitising it for display in the dash.

Can you look at the digital output and at the analog volts out with a good multimeter? You could also compare that volts out with the volts in on the dash on the live inputs page.

If my next ECU does not have native wideband control on the board I plan to use a CAN based controller to keep DC and extra conversion errors out of the picture.

[David Ferguson]

I would suggest you deal with the voltage offsets in your calibration. If as you said, the onboard O2 sensor (which I assume you're reading over ODB-II) agrees with the LC-2 on the PC. I would change the calibration table you have to get them to line up.

It's most likely a small voltage offset, so you can either fix it using the Online->Zero Sensors to a known value, or by changing the calibration table the necessary amount.

[FoxSTI]

I didn't have access to a pc all day today but I did manage to call motec.
They suggested I adjust the calibration voltages. Its going to be tricky since the WB jumps all around. I will report back this weekend. thanks to everyone who posted for the ideas.


But it is true, the LC2 reads the voltage form the Bosch sensor and display and AFR on the pc, but as mentioned I can also calibrate the 0-5 output however I like. I will report back.

[adrian]

One other thing you should do is set it to Absolute Voltage in the calibration, not ratiometric. Ratiometric is only if you are powering a sensor from the 5V supply on the dash.

[FoxSTI]

UPDATE

Hi Adrian, yes I did that also - I know you gave me that advice on another thread a while back. Made things more consistent.

Well, it was a PITA specially since the PC I am using is a MS surface and one have one USB port Need to get some sort of hub with at least 2. It took some tinkering but I was able to sue "read values" and plug in the ARF values suggested by innovate. Turns out the signal wire output 0.011v - 5.075v. Once I put those values into the Calibration setting table in Dash manager they are reading extremely close. It may just be the update setting on of dash also, because it seems like the Innovate LC2 is sometimes 0.1 ahead for a fraction of a second. Sure if that can be changed.

The innovate LC2 is updating every 1/12 sec.

Anyway, I am very thankful for everyone's help