JasonC SBB

I like that it's now faster and cheaper, but they took one of the best features of the LC1 (separate analog output ground wire), and deleted it.

Having a single ground wire results in an error in what the ECU will read from its analog output:

https://www.miataturbo.net/showthrea...ghlight=ground

Has anyone checked how much offset there is? One possible kludge is to beef up its ground wire massively (like 12 gauge), and if it switches the heater, to add a large capacitor near the gauge/controller.

Reverant

iTrader: (10)

It is really good. The problem with the classic LC-1 + DB gauge was that even when grounded together, there was an offset from what LogWorks was reporting and what the DB gauge was reporting. That is no longer an issue with the MTX-L, as the indication on the gauge is displayed directly from the "LC-1" circuit. So at least you now know the gauge is correct.

There is still however, an offset from what the MS is seeing.

It would be nice if Innovate could add a "calibration test" to the LM Programmer utility. You could enter the utility and force the MTX-L to output 10, 14.7 and 20 AFR, and then calibrate the MS to match these "known" values.

Pen2_the_penguin

iTrader: (4)

I was seduced into purchasing the MTX by Stephanie when she said the LC-1 was out of stock, and I am loving it! Very simple installation, and my readings is pretty close for my MS, and the software it came with helped me fix my fuel map... not sure if its the same software for the LC-1 but I am happy with the MTX. I just wish there were only one connection to the gauge from my laptop, not two different splitting input and output.

JasonC SBB

Won't work, because the ground offset voltage will vary with the heater current, which varies with exhaust temperature, or worse, is switched and you get 300 Hz square wave on top of it.

Dammit, here we go again with companies making newbie analog engineer mistakes.

I just realized there is a possible design solution to the single ground wire problem - I just did it myself years ago for a cellphone charger, it's called "cable drop compensation". Requires tho that you don't cut the cable it ships with to shorten it. From your description it sounds like they didn't do this. If they did it this way, I would put a warning tag on the cable.

Reverant, could you verify a few things:

First, temporarily program the MTX-L output to put out 2.5V all the time.

Measure the voltage right at the MS and check that it's exactly the same as what the MS software is reporting.

Key on and watch the MS reported voltage and note the error. Does the error stay the same, or diminish slightly as the sensor warms up? Is the error least if the exhaust piping is good and hot? Does the offset seem to jump up and down between 2 values in real time?

Disconnect the connection to the sensor itself. This means there will be no heater current. Make sure that the MTX-L software is set to output 2.5V during an error condition. Look now at the MS reported voltage. Is the offset gone? Reconnect the sensor and do the cal run. (I presume it requires that fresh air is in the exhaust - I run a shop vac on my exhaust pipe LOL)

I presume that the sensor heater controller is inside the gauge. Take a voltmeter, red wire, and probe the ground wire where it enters the gauge. Connect the voltmeter black probe to the other end of the ground wire (ECU? cylinder head?). Key on. Does the voltage drop on the wire match the offset error between the MS and the gauge?

Ben

iTrader: (33)

We have an LM-2 on the dyno. It's display matches logworks very well.

The LM-2 uses the same controller chip as the MTX-L. I have yet to install an MTX-L but also have yet to hear anything negative.

Reverant

iTrader: (10)

I don't have one right now to test, my experience comes from a couple of units I installed in customers' cars along with Megasquirts. Said procedure makes sense, I will keep it and perform it when I have a MTX-L in my hands to test.

Ben

iTrader: (33)

You can reprogram the analog output to stay at a fixed voltage, then measure the voltage on the wire with a DMM.

Reverant

iTrader: (10)

Ben,

I also have a LM-2, but I'm not exactly thrilled about it, especially when compared to my LM-1. Specifically, the LCD is quite slow to update and the datalogging to SD card doesn't work (no card works with it, not even the one provided by Innovate!)

Ben

iTrader: (33)

I own an LM-1 but never compared its display speed to the LM-2. I've used both a fair bit, and they've both worked well for me. We installed an LM-2 in MegaManiac and used it to datalog wb x 2 and egt x 8 on the SD card during trips down the track.

I don't own an LM-2 personally, but have used the one on our dyno and the one in the drag car. I remember opening up the one for the drag car and soldering in a cap across the power supply for some reason--but I think it was because the LM-2 was backfeeding ripple into the car, and we were trying to eliminate as many sources of noise as possible.

GrahamC

iTrader: (4)

I've got an mtx-l and have had an lc1 in the past. No complaints, and a lot easier to set up than the lc1.

JasonC SBB

Yet more newbie-style analog engineer mistakes corrected by hacking.

Matt Cramer

That drag car was a real challenge to get the electrical noise fixed. The coils we were using are known for killing the OEM ECU with noise spikes, with all the R&D time they must have put into testing their ECU and wiring harness. And we were running considerably more dwell time in an effort to get a hotter spark.

PeteNMA

What I'd like to know is do you have to have the gauge active all the time for the output to work? I want to be able to switch it off for driving at night

Reverant

iTrader: (10)

With the MTX-L, you can't somehow switch the gauge off. It does have a dimming feature though.

PeteNMA

I'll stick with the LC-1 then, thanks