General Innovate MTX-L - gauge doesnt agree with analog output

[Spades]

I have an Innovate MTX-L wideband. The analog WB output is connected to my rear O2 and the output voltages im getting are between 1.08V and 1.24V. Using the formula V x 3.008 +7.35V equates to between 10.6 to 11.0 AFRs, but my wideband gauge reads between 10.0 to 10.4. Is the formula not correct or something not right with the simulation?

 

[Spades]

So which reading would you trust? The digital gauge or the output voltage?

 

[TalonSpeed]

Check your ground wire for the WB and the gauge. U using link? i had that issue before and fixed it.

 

[Spades]

The ground is tapped to the negative of the cig lighter, the positive is tapped at the oem fuel pump relay. I chose this positive so that the WB turns on with the engine running rather than the ACC ign key position

 

[mschlanglv]

Your WB should be grounded to the same spot as the ECU sensor grounds. By grounding it at a different location, there is the potential for a voltage offset between the WB ground and the ECU ground. This offset would skew your reading, using your formula .1v offset would change your reading by ~.3AFR.

 

[GSLENK]

Open up logworks, compare, and adjust? I did this, I took a cell phone video to make sure my comparisons were accurate, then adjusted. This is how I got link, gauge, and LC-1 all on the same page.

 

[curt-s]

Your WB should be grounded to the same spot as the ECU sensor grounds. By grounding it at a different location, there is the potential for a voltage offset between the WB ground and the ECU ground. This offset would skew your reading, using your formula .1v offset would change your reading by ~.3AFR.

Do not do this. For the MTXL, Innovate states you use a chassis ground for the ground (BLACK) wire or the negative battery post. The LC1 can use a sensor ground, as it has a separate ground for the heater. If you ground the MTXL through the ECU you will likely blow the sensor ground trace because of all he amperage it needs for the heater.

 

[Nate355RS]

Just FYI, don't ground the LC2 to the ECU either.

I tie the gauge signal into the same wire that goes to the ECU, then they both read the same. Some will say it'll throw the readings off, but it won't. I also isolate the ground so the only thing at the wideband grounding point, is the wideband.

 

[curt-s]

Generally, no, as the ECU is not the regulated voltage source to the sensor. The sensor gets its voltage from somewhere else and self-regulates. The LC1 information was from ecmtuning's hookup guide for LC1.

 

[Spades]

So where should we ground the MTX-L wideband? And can i keep my positive source tapped off the OEM fuel pump relay? Since its a popular mod to the the fuel pump rewire, the oem fuel pump relay is now only being used to trigger the aftermarket relay, so i see no interference to tap my positive off this lead

 

[Nate355RS]

Grounding it to the battery post would be ideal. But a good chassis ground all by itself usually does the job too. For power, as long as it's a switched source you should be fine. Don't see why the stock pump relay wires wouldn't work.