Wideband O2 setup questions

Hi,
I've finally got around to making up a cable to connect my Inovate MTX-L AFR gauge to my Moates APU-1 so I can start logging with wideband data.

My problem is there seems to be a .5 difference in AFR between what the MTX-L gauge shows on it's digital display and what I see on the TunerPro dashboard e.g. 15:1 is shown on the MTX-L while 15.5:1 is shown on the TunerPro dashboard.

I have an 8625 8192 Baud PCM $0D Mask ID.
I followed EagleMarks ADC Interface channels setup guide to edit my ADX file so that it could display the output from the MTX-L.
I initially set it up with the payload size set to 63 but had no activity on the dashboard so I then tried a value of 65, on cold start TunerPro was only displaying the AFR in the 10:1 range while the MTX-L gauge was showing around the more believable 14:1. I then changed the payload size value to 67 and things started to look like they were working.
I've connected to ground and channel 1 on the APU-1, according to the guide the value 67 corresponds to channel 3?
I'm not sure why I had to change that, does the payload value vary between different bin's?
Any idea why my MTX-L display and my TunerPro dashboard are out by .5 and what the proper way to sort it out?
I've attached the values I've set up in my ADX file incase someone can see an obvious mistake.

Be sure to configure the MTX-L so 0 volts = 10 AFR and 5 volts = 20 AFR.

I do not use the API-1, I connect the MTX-L 0 - 5 volt output directly to Pin B16 on the '8625 PCM using the instructions on this thread: http://www.gearhead-efi.com/Fuel-Inj...29-Spreadsheet


Try using the attach $OD adx file with the MTX-L going directly to Pin B16 on the '8625 PCM

dave w

Hi Dave,

I'm assuming my MTX-L is set to the factory default of 0V = 7.35 and 5V = 22.39 AFR which seems corresponds to the values I've entered into my ADX.
If I change the MTX-L to 0V = 10 and 5V = 20 AFR won't I then have to change the values in my ADX?

I'd like to see if I can get this setup working before I switch to a different method of signal input, at least with what I've got at the moment I know the MTX-L gauge and the APU-1 are working with a common ground, once I run a single wire to pin B16 from the MTX-L there is a potential for a slight variance in the grounding.


On a side note, how do you connect a wire into the spare terminals in a PCM is it a completely empty terminal hole or is there a terminal in there that can be removed and crimped/soldered onto? Keen to try the two speed fan control via pin E3 someday.

I have not modified an adx file for using the MTX-L with 0v=7.35 & 5v=22.39 AFR's parameter.

My experience shows their are ZERO issues with a common ground for both the PCM and WBO2.:thumbsup:

Here is a link for re-pinning the connectors used on the '8625 PCM: http://www.dynamicefi.com/RePinHowTo.php

dave w