So I just hooked up the ms3 pnp pro on my 97 Miata. I also hooked up an Innovate MTXL wideband and the gm iat sensor at the same time. I'll be going turbo in the future.

My problem is that the mtxl is reading the correct 14.7 afr at idle, but Tunerstudio shows the afr just above 10. I have checked in TS and calibrated the afr. I've even tried doing the custom afr by voltage that shows in the mtxl manual. When i do.that the afr goes even lower. I've already searched this issue. I connected the 12v switched wire to the power wire from the annoying door chime plug that was already unplugged. I hooked the ground up to the same ground that the ecu wiring harness grounds to (the one at the back of the intake). I then plugged the yellow output wire into the analog input 1 on the options connector at megasquirt.

Does anyone have any ideas? Picture attached of gauge (dont mind the error box, that's another issue I'm having).

 

Did you get the MTX-L used? You can use LMprogrammer to change the output voltages from the default 0v = 7.4 to 5V = 22.4.

Can you measure the voltage on the yellow wire while idling around 14.7? You should see around 2.43V. 10.3V would measure around 1V. Math for volts from AFR is AFR minus 7.4 times 1/3.

I don't know off my head where the chime gets power from, but that has to be the most creative way to power a wideband I've heard yet. Are you absolutely sure it provides enough current?

 

It's a brand new mtxl. I only used the chime for power bc it's a 12v switched and I already had it unplugged. The mtxl didnt give an error for low current. I calibrated the sensor per innovate instructions and then calibrated it in TS. I tried doing the custom wideband in TS and set 0v at 7.35 and 5v was 22 something. This actually made the afr fo even lower on the TS gauge.

 

Check the output wire of the MTX-L, is it varying voltages between 0 and 5v? If it's stuck on 14.7, there's probably a sensor error, its probably outputting 0v, and TS would be reading correctly.

 

its not stuck on 14.7, it varies on warmup and idle and while driving.

 

I found the problem. The problem is.that I am an idiot. I had the wideband wired into analog input 2 and had TS set to.the wideband coming from analog input 1. Changed TS to read input 2 and boom! Problem fixed.

Its reading within .4 of the wideband gauge sonI can correct that by playing with the voltage in the calibrate menu.