Today I filled up my 2009 touring for the first time and adjusted the tire pressure to 38/36 (and reset the TPMS). Driving home, I noticed that the MPG readout gauge on the MFD was reading a lot different than before. For example, when braking, the MPG was saying I was getting 52 mpg and going down (instead of 99.9 mpg). When in electric mode, it used to read 99.9 mpg, now it was anywhere from 50-75 mpg. Is this normal behavior?
What stage of warm up were you? If the car was still warming up, then yes, that's normal, as your ICE was probably still running.
That just sounds like it wasn't fully warmed up yet. At what point did you notice this - i.e. how long after starting up the car? If it was in the first 5-10 minutes that sounds normal. On cooler days I also notice that the engine will start warming itself again after I go for an especially long time in glide or electric mode. Tim
I drove it probably 10 min, refilled the tires, reset the TPMS and let it sit for a few minutes. Then drove another 5-10 minutes home. Will be driving the car a little later tonight, will to see if the same thing occurs. First time I noticed mpg declining while braking before.
Sounds like the car is in Stage 3a, wanting to do its idle check before going into Stage 4. See The Five Stages of Prius Operation for more on these 'stages'. The solution is to slow to below 6mph (or stop) and wait, without pressing the accelerator, for 10 seconds. Once it gets below 6mph the engine goes into idle mode, and it takes 10 seconds to check that the idle is stable before it will go into Stage 4. If you apply gas even slightly, it comes out of idle and you have to wait another 10 seconds once it goes back in. The car seems to need to know that the engine will idle properly under closed-loop fuel control before turning the engine off below 34mph, and I think before doing fuel-cut above 42mph. Anyone know if the 2010 car still features this idle check?
