LC-1/2 default WBO2 setting in TunerStudio

[dpstark2]

I have two cars with MS3. One has an LC-1, the other an LC-2. When I connect to either with LM Programmer, I see the WB output is set to 0 = 7.35 AFR and 5V = 22.39AFR. Why does the default AFR calibration for LC-1/2 in TunerStudio show different values that don't map to the same line? I don't have it in front of me, but it lists something like 1V = 9.4 AFR and 4V = 18.4 AFR. The slopes of those lines end up being very similar, but the points do not match up.

I used LogWorks and it looks like TunerStudio is showing the same AFR as LogWorks, but I'm curious. Is this due to some interaction with the MS3 circuitry and the WB controller? I just want to make sure I've done this right since I'm bringing up car #2 and have been driving car #1 for a few years this way.

[benckj]

Running an LC1 myself and have found the lower value needs to be 6.35v in order to agree with the Innovate gauge and Tuners wideband. Set-up using a generic gauge rather than TS default.

jim

[dpstark2]

Thanks for the reply. Can anyone else weigh in on this? The difference between the two potential calibrations is somewhat small, but it certainly would make a difference.

[benckj]

Search around the forum as this difference has been discussed several times before.

Jim

[dpstark2]

I have searched around and noted people making similar comments. Most of the responses are "make it match your gauge." OK, that's fine. But I'm asking why the default in TunerStudio is different than what the controller actually uses. And all the directions and setup info I've found say to use these defaults, so it would be good for everyone if there was an answer to this question. If the real procedure is to calibrate it yourself, I'd like to get that info out there too.

I have a plan to calibrate mine with the tools I have on hand. I'll do that and post it here once it's not 110F in my garage. Or 130F with the 440 running.

[Blown88GT]

... I see the WB output is set to 0 = 7.35 AFR and 5V = 22.39AFR. Why does the default AFR calibration for LC-1/2 in TunerStudio show different values that don't map to the same line? I don't have it in front of me, but it lists something like 1V = 9.4 AFR and 4V = 18.4 AFR. The slopes of those lines end up being very similar, but the points do not match up...

The limits are different but the curve (straight line) is almost the same.
LM Programmer uses 0 = 7.35 AFR and 5V = 22.39AFR.
TS Calibration uses 1.0 = 9.7 AFR and 4.0V = 18.7AFR

If you plot the curve, the endpoints (0-1V & 4-5V) are very slightly non-linear with the 1-4V. This is likely why TS doesn't use them. You will never be operating in those ranges, so they can be ignored.

Next time you go into the AFR calibration menu, the AFR selection you used last time is NOT highlighted (because neither MegaTune nor the MegaSquirt® controller store this value), however the AFR table is still in place and should give the correct readings.

[dpstark2]

Thanks.

My guess was that it had to do with the transfer function of the circuit, LC-1 output, and ADC in the ECM. In the end, I did the following to verify that it was all close enough to correct. I set the LC-1 to output 0V at warm-up and recorded volts and AFR during warm-up. I repeated this with 5V during warm-up. The gauge showed something like .3V and 4.9V respectively, but AFR was nearly correct at 7.3 and 22.3 AFR. So (of course) whoever developed the calibration either experimentally or empirically figured out what was necessary to get the right readings. I also repeated it with 2.5V to verify I got the right AFR in the middle of the curve too.

Hopefully if anyone else has this question, this will help.