romandian

i installed the lc-2 (3795) on my new vette, performed the free air calibration and its consistently showing 14.8 at idle. innovate sais thats normal. well, i know its not, my other gauge shows a little under 14.7. im afraid the 0.1 off might get larger at richer mixtures in whatever direction. i dont trust the gauge.

what do you guys think?

(im surprised you even have to calibrate it, my other gauge i didnt have to.)

aaronc7

Are you reading the AFR off a gauge and if so which gauge, or off your computer? what is your other wideband?

romandian

https://www.innovatemotorsports.com/...roductid=16235

the other one is edgetech.

aaronc7

The DB gauges is connected one of the LC-2 analog output wires right? Yellow I think it is. There will be a voltage offset error for such a setup. The MTX-L is the better choice here IMO because the gauge is displayed from controller over serial/direct connection and there's no voltage offset nonsense to worry about. If you connect the gauge to your laptop and view AFR thru the Logworks application I'm betting it will match what you're expecting.

You can connect to the LC-2 via Logworks and also change the analog signal output...i.e. tweak the Voltage vs AFR slope so it reads spot on. I hope that makes sense. Little bit of a pain in the butt, but I've done this in the past and it solves the issue. You can also temporarily configure the gauge to always output a particular AFR number, then you can compare that to what the gauge says... make a little spreadsheet chart to see the current error across the whole AFR spectrum. Let me know if that doesnt make sense and you want to give it a try... I can try to explain/show better.

romandian

yellow it is. as to the offset, i thought the calibration was supposed to eliminate that. where do you get logworks from?

well, anyways, apparently it doesnt work out of the box, they think 14.8 is o.k. and its one of the more popular gauges. dont know what to think. time to get another one i guess. $219 down the drain and i see the mtx-l for $160 on ebay new. i got this one mainly to avoid the stupid and distracting diodes. the mtx-l has no controller, right?

dmaleck

From my research the AFR500v2 is the way to go!

aaronc7

I agree that a lot of these little discrepancies don't get discussed and most simply overlook it. Before this project I had a turbo miata running on Megasquirt/speed density that used the analog output of the wideband for tuning-- so getting it accurate was essential.

The MTX-L is more or less the same under the hood from what I understand, and the controller is internal to the gauge, but yeah no external box or anything. You wire the sensor right into the back of it.

The only gauge that I know of that corrects for voltage offsets in it's analog outputs is the new AEM x series gauges. Otherwise it's just the nature of the beast when dealing with analog signals. With my miata and the MTX-L, my gauge was spot on, but the signal going to the PCM was off by a little, so I had to correct so they matched.

You can still get this one up and running 100% though. Logworks is located on their website support section (you actually need the sub application called LM programmer to do this though, but it's part of the same software suite). I can get you a link if you need it. I'll type up a little how to correct the reading and post it up here when I'm done

aaronc7

See pic below for snippet from the user manual and what the settings look like in the software.

You basically need to tweak the linear curve a little bit such that the gauge displays actual. The default settings are basically AFR = 3 * V + 7.35 in linear equation format. You could simply experiment by subtracting 0.1 in the two "AFR" fields in the software and that would probably get you close (it says Lambda in the example).

If you really want to get it spot on, set both voltage inputs to the same number, this will basically 'flat line' the curve and make it always output a certain voltage regardless of actual AFR and as a result the gauge will display what it believes to the AFR based on the voltage and above equation.

So if you set 0 volts for both, you would expect to see 7.35 on the gauge... If you actually see 7.45 let's say, then it's reading 0.1 high, so you would want to subtract 0.1 from the first "AFR" box. Then do the same thing for 5V in both boxes. You can also do 2.45 volts which is 14.70 AFR exactly.

I made a quick and dirty excel chart also below.... in my experience at higher voltages the offset was greater, but either way it's just a matter of slightly tweaking the numbers to get the end result that you want. I'd also do this with the car running just to replicate actual driving conditions as much as possible.

At the end of the day, I think the MTX-L is probably better suited for your usage, so swapping to that is also an option. Just remember if you use the analog outputs, all of this is still 'required' if you want spot on numbers (like if you wire it into Hptuners or efilive). I have a LC-2 but I use serial output into my Efilive FlashScan.

P.S. I do give Innovate props for making the software available to see/change all of this stuff though. I think most products what you get is what you get and for most ignorance is bliss (and 0.1 point generally isn't a big deal to most people).... I'm with you though, that 0.1 does matter, lol.

romandian

i think the afr is good, what puts me off is the box shape. aaron, thanks, maybe ill dive into this over christmas.

aaronc7

Something else you could try if you haven't done this already is ground the DB gauge and LC-2 to the same exact spot.

tblu92

Such a small deviation at P/T or closed loop is meaningless---- there may be several reasons why you get a small difference in readings in CL --Your reading annomollies are less than 1% so don't worry !!!!
At WOT if you get different wideband readings make sure you record them only in the trans gear ratio that is closest to 1:1------If you record 02 data in an underdriven gear it will read rich which is OK But you would want to achieve your target WOT 02 reading in the gear ratio that is 1:1---
Even then if you get a mismatch in 02 readings at WOT from 2 different 02 sourses just error on the side of RICH--Even at WOT less than a 1% difference will not cost you any HP or TQ