Gen III and ScanGauge II LOD Question

I have read several threads concerning the LOD readings and the Gen II's. It appears that the LOD readings for the Gen III's are much higher than the Gen II's. I have seen posts for the Gen II's where to get the best efficiency the LOD is kept in the 40's and 50's.

What exactly is the LOD reading? The ScanGauge manual description:

This is a percentage of the maximum power available currently being generated. In some vehicles it is the maximum available for the present RPM.

What I have observed is that the LOD remains around 83% most any time the ICE is running, especially at highway speeds. It takes a fairly good downgrade for the LOD to drop much below 80%.

I have read where the Prius tries to keep the ICE in the "sweet spot" which seems to be at a given RPM and LOD. Is what I am seeing where it is trying to stay in this sweet spot and use the electric motors to trim?

 

I thought about having read Hobbitt's "Tao of HSI" and went back and read his article again and this answered my question. He confirmed my observation of the LOD signal being in the 80 to 85% range.

He explains it this way:

Remember the "sweet spot" meter concept? Well, here it is, straight from Toyota. As the HSI reaches up into the area I've shaded green here, engine load as reported by the ECM rises to about 80% and pushes toward 85% by the top end of that range. This means the throttle is controlled so that the engine is steadily producing most of its available torque, over a fairly wide changing range of RPM between roughly 1200 and 2100 as the pedal pressure is varied and speed changes.

Constant high torque, and variable RPM to obtain the desired overall *power*. That's always been the key to it, known to every efficiency-aware driver whether they're in a hybrid or not.

Thanks Hobbitt.