OBD reported Load vs ECU Load

Discussion of tuning specific to fourth generation (ND) MX-5 Miata vehicles
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mangosmoothie
Posts: 4
Joined: March 27th, 2022, 8:12 pm

OBD reported Load vs ECU Load

Post by mangosmoothie »

I live at 5000 feet elevation. I believe the load I log is corrected for normal temp/pressure. The ECU uses uncorrected load for spark and vct calculations. So this makes datalogging and tuning a little difficult since I have to guess what load the ECU is using.


When I had my NC miata, a similar issue presented itself. LoadAbs (OBD) = (AirDensity * LoadScaled) / AirDensityNTP
where airDensityNTP = 0.0012, and LoadScaled = load corrected by the load scaling table.

So, in short, I believe the OBD load pid is corrected. The ECU uses uncorrected load for spark and vct calculations. So this makes datalogging and tuning a little difficult since I have to guess what load the ECU is using.

Can we try and get an uncorrected load to log?
mituc
VersaTuner guru
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Re: OBD reported Load vs ECU Load

Post by mituc »

What you're basically describing is pretty much the difference between calculated and absolute load.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
mangosmoothie
Posts: 4
Joined: March 27th, 2022, 8:12 pm

Re: OBD reported Load vs ECU Load

Post by mangosmoothie »

only absolute load is available to log. It would be nice if calculated load was added then.
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