Tired of Wideband/HPT Discrepancy: Going to Try Something

[Engine_HP]

Thats the whole point of the thread, that the technically correct formula is not yielding the right results. And no it's not acceptable (IMO. Your slope is incorrect, and perhaps even the offset. So you need to know what voltage HPT is seeing when the LM is saying a certain AFR. As I've done log the voltage coming in from the EIO and take a video of the HPT EIO voltage and LM2 AFR at the same time. Go through it frame by frame and record the EIO voltage and the LM2 AFR in the spreadsheet I attached which will give you your new slope. Then take digital photos of the LM2 AFR and HPT AFR and adjust the offset up or down until they match. Then the formula you end up with is representative of your particular setup.

if i do this on my car will it work with all other cars, you know each car has different volts, batt ect..

Just from what youve said I can tell you your curve is too flat and your offset is too small.

Try "volt/.5 +12"

the 0.6265 came from the eq, 5 / 7.98 = 0.6265.

i have notices if i add on the offset i get them both to match @ 14.7 and as the afr increses (like 13, 12, 11, 10) the the two gauges starts to walk away from each others.

ill give the "volt/.5 +12" a try today and see how it gose, other wise ill stay the numbers i currently have.

[5_Liter_Eater]

if i do this on my car will it work with all other cars, you know each car has different volts, batt ect...

The slope should remain the same but the offset may change from vehicle to vehicle.

the 0.6265 came from the eq, 5 / 7.98 = 0.6265.

ill give the "volt/.5 +12" a try today and see how it goes.

Don't. You have it right based on how you have your LM2 configured. It just needs to be validated using the procedure I layed out in this thread. Based on the three data points you gave, it does need to be flatter (smaller) but don't just plug in different slopes and offsets and hope it works, use the procedure and know it's right.

[mr.prick]

It's probably just the time between the LM-2 processing data from the sensor into output voltage to the interface & the interface/software converting voltage into AFR.
There are slight discrepancies with analog and serial even with latency speed set to instant, here is an example.

[5_Liter_Eater]

For me this was not the case. The calibration tune I put together allowed me to slowly increase RPM's in neutral and as RPM's rose, AFR dropped. So AFR was not changing rapidly. The voltage output was always pretty much the same. You can see from the spreadsheet that while theoretically there should be zero volts at 10:1, HPT was seeing .63V. But by 14:1 I was seeing ~2.4V when I shoud be seeing ~2. A difference of only ~.4 so the voltage output (that HPT is seeing) is off from theoretical.

[Engine_HP]

(Max afr - Min afr) ie 20afr - 10.0afr = 10 (then divide by voltage) 5.0v/10 = .5 + min afr

so hpt eq should be .5+10 if it does not match then ground offset is the problem. hpt is grounded @ the aldl ground and not the cyl head or batt. How long the ground wire is from each will effect offset as well.

i have the max afr 17.98 and min afr 10,

17.98 - 10 = 7.98
5 / 7.98 = 0.6265

am sure i am correct here.

[5_Liter_Eater]

Those are the correct theoretical numbers, yes. Since the lowest AFR is 10 the equation would be v/.0.6265+10 (theoretically).

[Engine_HP]

thanks 5_Liter_Eater,

ill try running it direct from the battery and see what happens.