LM-1 Ground Offsets

[PurplePiss]

Hmm.. I tried using the HPT canned PID for the LM-1 and couldn't get the LM-1 screen to match what HPT was showing.

I finally did 0-5v, 10-18 AFR in LMProgrammer on Analog 2 out, then created a PID in HPT with volts/.625 +9.68. When I set the voltage in LMProgrammer to 2.5, HPT read 14.0 only when I had the 9.68 in there, not 10. Then I programmed it to 0-0volts, and HPT should have reported near 10 AFR, but it was 9 something. I'm afraid I'm only accurate near stoich. Is it because when you set it to 0 volts, your seeing the voltage of the MPVI? I guess I should check 5-5volts and see if it shows 18 AFR in HPT?

[jimmyblue]

I still believe you're at the mercy of heater current that
is a variable w/ exhaust flow, near-exhaust airflows and
ambient temps. Do not think you're going to find a magic
number that stays put, and even the cig lighter contact
wipe resistance is going to vary on you day to day. So
the I*R rise that the heater throws down against the
OBDII version of ground is not anything to be relied upon.
Plus you have the second power jack at the unit end as a
variable contact resistance. It all stacks up and it's all bad.

[PurplePiss]

So where does that leave me then?

Is this ok?

I finally did 0-5v, 10-18 AFR in LMProgrammer on Analog 2 out, then created a PID in HPT with volts/.625 +9.68.

[IanB]

So is it the analog out ground, or the lighter plug ground that needs to be fortified, or both? I'm going to try and fiddle with this tonight, and any info would be great. Nice to see that I"m not the only one having issues with this.

[PurplePiss]

Do you think if you did a calibration when the car was in DFCO and everything was hot, that it would make the numbers more accurate?