Scangauge Open/Closed Loop

[Lithium]

I've discovered a very simple feedback method for maximizing fuel economy on the Prius. I recently completed a 1600 mile trip and experimented with the OPEN/CLOSED LOOP (OPEN/CLSD LP) gauge on the Scangauge II. What I discovered is that anytyime the LOOP gauge is set to open then either the engine is not spinning or the engine is spinning but the injectors are turned off. By maximizing the amount of time that the car is in OPEN LOOP, I maximize my fuel mileage. I verified that the gauge gets set to open when the car is:

• In EV mode
• Not in EV mode but the engine is warm enough and the demand is low enough that the engine stops spinning
• Warp stealth mode (engine is spinning but injectors are off)

With the open/closed loop gauge, you don't have to monitor many things at once (e.g. RPMs, energy flow, battery current, etc.) and I've found it's much easier to explain to untrained people how to improve their mileage. Now if I can just figure out how to translate the open/closed loop OBD command into a green/red indicator light, I could add a "maximum economy" light to my Prius.

[2009Prius]

You do realize that excessive use of the HV battery will hurt fuel economy, right?

[Lithium]

I have the HyMotion conversion installed which gives me an extra 5KWH to play with.

[2009Prius]

Originally Posted by Lithium

I have the HyMotion conversion installed which gives me an extra 5KWH to play with.

If so then you should have warned about this in the original post since most people don't have the luxury of plug-in yet.

[Lithium]

True. When running in open loop mode, though, the car is not always burning extra battery juice. In fact, I found the open loop mode most helpful in allowing me to maintain warp stealth mode where the engine is spinning but the injectors are off and I'm coasting along with no current to or from the battery.

Having the Hymotion pack is nice though when I want to extend my EV glide with power flowing from the battery for about 10 miles :-).