Question regarding HSI reading during warm up

[indianagreg]

If this has been addressed elsewhere, please point me to the thread. I searched, but couldn't find it if it's out there.

During the last two mornings, within the first 3/10 to 4/10 of a mile I observed something that I hadn't noticed in the three weeks I've owned my Prius. The hybrid battery was at three bars (the same position it had been when the car was started), I was accelerating in ECO mode with the indicator near the center of what PC member Ken1784 has called the pulse zone (right quarter of the ECO bar), I was at around 35 mph, when suddenly, the reading on the mpg meter shot up to 100 before quickly declining to about 25 (or even less); meanwhile, the hybrid battery had declined to two bars. I'm not sure (as it's happened so quickly), but it seems almost as if the ICE shut down and then immediately restarted. My pressure on the accelerator was as constant as it could be. (I have no idea whether or not it matters, but the A/C was "on", but not running; the morning was too cool.)

Does anyone have any idea what was happening?

Thanks!

Greg

[a64pilot]

Does sound like the ICE shut down. Shouldn't, but it does sound that way. The only time I have seen what you describe in mine was after running it out of gas, except of course it didn't re-start.

[ken1784]

Originally Posted by indianagreg

I was at around 35 mph, when suddenly, the reading on the mpg meter shot up to 100 before quickly declining to about 25 (or even less); meanwhile, the hybrid battery had declined to two bars. I'm not sure (as it's happened so quickly), but it seems almost as if the ICE shut down and the immediately restarted.

My guess story is as follows;
- You were in the Stage-1a of warm up cycle until the first 3/10 to 4/10 of a mile, approx 1 minute from power on.
- During the Stage-1a, the ICE runs for warming up the coolant and catalyst. The ICE does not drive wheels, therefore Prius is driven by electric only. Then, it causes the battery SOC down.
[guess mode on]
- End of the Stage-1a, a short period fuel cut was happened, and you saw the 100mpg bar. It was a transition period.
[guess mode off]
- Then, you were in the Stage-1b or Stage-2 after that. You saw 25mpg or some number on the mpg meter.

Ken@Japan

[indianagreg]

Originally Posted by ken1784

My guess story is as follows;
- You were in the Stage-1a of warm up cycle until the first 3/10 to 4/10 of a mile, approx 1 minute from power on.
- During the Stage-1a, the ICE runs for warming up the coolant and catalyst. The ICE does not drive wheels, therefore Prius is driven by electric only. Then, it causes the battery SOC down.
[guess mode on]
- End of the Stage-1a, a short period fuel cut was happened, and you saw the 100mpg bar. It was a transition period.
[guess mode off]
- Then, you were in the Stage-1b or Stage-2 after that. You saw 25mpg or some number on the mpg meter.

Ken@Japan

The one minute is probably about right. I generally start the car and as soon as "Ready", back it out of the garage.

Ken, if your guess mode is correct, then is this or might this be abnormally significant, i.e., as this point no one else seems to have experienced or reported this aberration? Also, is there anything I might do differently (or does it even matter)?

Thanks for your thoughts!

Greg