MTX-L readout discrepancy
 

Hey guys. Hoping you could help me figure out what is going on with My GEN2 PNP. I have an MTX-L guage with the 0-5v signal connected to the stock narrowband input. When i open and monitor with Tuner Studio, it is reading at .5 lower than the innovative gauge is. This is with the calibration set to the LC-1 if i recall correctly. If i go custom and manually enter the amounts that were included with the MTX-L instructions, it reads even further off. Has anyone experienced this before? What am i doing wrong here?

Why do you have it connected to the narrowband input?

Because that was one of the two options in the megasquirt manual. i have completely eliminated the stock O2 so i used the stock input to the ECU rather than the option port.

"There are two ways of connecting the controller to the MSPNP2. You can either connect the analog output to the pin labeled Oxygen Sensor input of the option connector, or you can cut and splice the oxygen sensor signal wire to the analog output. If you use this pin for wideband input, you must disconnect the stock oxygen sensor. Do not ground the oxygen sensor wire if you disconnect it; leave it completely unconnected and taped off if necessary (make sure it can't short to ground or anything else)."

wideband to the MSPNP will be more beneficial in terms of tuning and logging and just general access to more information

I have my MTX-L Wired into the factory O2 input wire (just chopped off the wires off stock narrow band, wired my widebands output into the signal portion). Works without issue.

As far as MS calibration, I too had offset when using supplied data from innovate, as well as the LC-1 defaults. The output of the MTX-L is linear, so you can fiddle with the custom-wideband settings until it matches. If it's consistently off .5 across the whole range then just increase/decrease both the 0v and 5v readings .5 depending on which direction it's off. Should be about dead on then.

ALSO! Make sure your wideband grounds to the same place as the ECU with a dedicated ground wire. That makes sure there is no voltage offset between the MTX-L and the ecu.

OP says "narrowband" so question is are you trying to display the narrowband output from the mtx-l (brown if I recall)?

If so relevant question is why?

I read that as he has his MTX-L 0-5v wideband output wired through the cars existing O2 'narrowband' wire input. Aka he's feeding the mspnp his wideband signal through the stock O2 harness connector.

Thats exactly what I do and have had no problems once I corrected my offsets via the custom linear wideband option in Tuner Studio.

This is correct. I will play with custom data to see where that gets me. I will also make sure my grounds are the same along with voltage input. Your input is greatly appreciated.