I have owned my 2012 Prius v wagon for a year and a half and I've had the ScanGauge II almost as long. My commute to work is : 33 mi, 40-45 mins, 90% freeway one way. I'm beginning to notice an inconsistent issue while gliding on the same downhills every day. Normally, I get 9999 mpg/ 0.00 gph easily while the ICE idles at 992 rpm. Lately (randomly), it won't go into 9999 mpg but 200ish mpg intead with the gph at 0.36. My first glide is for about a mile after driving for about 15 minutes. I called it inconsistent because because one day I get 0.00 gph, the next 0.36. It doesn't appear to be related to temperature since the issue happens at 45*F or 56*F. The coolant temp is 190-195 and SoC is at 59-60% fairly consistently. It doesn't matter if I'm driving with cabin heat on (not defrost, fan on low) mode and headlights off. I do have a Garmin GPS pluged into the 12v outlet. However, unplugging it doesn't affect the outcome. One more thing... on the same drive it may finally go into a 0.00 gph glide later and then back to 0.36 gph at a later point. And, to complicate the issue... the SG will sometimes show 0.02 gph while in EV mode. I know that issues like this are tough to diagnose on a forum but I'm hoping that someone may have run into the same problem and figured out the problem. Is this an issue with the ECU reporting inaccurate gph at times? SG issue? 12v needing extra recharging? an airmass flow sensor issue? Throttle position sensor issue? Any clue?
When you see this happen, turn off the air conditioning/climate control by pressing the OFF button. See if that makes a difference.
Great question. It has no effect. With the high temps in the 50's in the PNW, I don't use the heater that often.
Well if it makes you feel any better, I see the same thing. I have like a 2.5 mile stretch just before I get home (after 13 miles on the highway) that is downhill @ 50mph. Most of the time I can get it in that special zone where it revs at 992 and no consumption 9999 mpg. But every now and then it insists on running the engine and get 180-200 mpg range. The SOC is normal (about 2-3 bars down from max), heat set to 67, ICE temp usually around 180-190F. It is pretty rare so I don't fret about it much.
Good to know. Mine is doing it 1/2 to 2/3 of the time. On EV, now I see 0.02 gph the majority of the time. I wonder if a CTL-ALT-DEL (disconnect the 12v batt) would help clear a glitch with one of the sensors.
Of course if the engine's got to turn anyhow above 43 mph I actually prefer that it consume 0.2 gph or whatever rather than drawing on the battery for that purpose.
It is quite possibly an SGII issue. The basic GPH gauge is known to give a false reading when it should be detecting a fuel cut situation. You will several references to this on the main SG threads here. There are work arounds including using an alternative Xgauge called gph from Ken in Japan.
Thanks. That makes sense. I'll try the Xgauge GPH. Today with temps in the low 40's and using cabin heat I could easily get 9999 mpg/ 0.00 gph. Go figure.
Here's the link to the Xgauge from last year. I don't think it's made it into Adrian Black's spreadsheet. ScanGaugeII work on 2010? | PriusChat
In the process of trying to figure out this mystery, I notice that the SG is reporting horsepower even when the car is in READY mode parking brake set. It shows 0.2 hp along with a fuel flow of 0.02 gph. I'm beginning to think that this erroneous horsepower reading is the source of the problem. When I finally get to see 9999 mpg, the horsepower indicates 0.0 instead of 0.2 Maybe others can verify this when you don't see the 9999 mpg when gliding. Does anyone know if horsepower is reported by the ECU? Or is this calculated by the SG? In either case, I'm going to send my SGII for the 4.02 firmware update.
Hey Al did you get your SG back? did it help? I live more or less at the top of a 2000 foot hill. I do have some flat and a tiny uphill before i hit the 1700 ft or so drop downhill. My daily commute I've noticed very inconsistent 9999 mpg, tho mostly it does get that. At halfway down or less, soc tops out, and revs increase, you'd think that at some point always i'd get the 9999 right? Even in icy winter, i will mostly hit 9999, but even hot summer mornings, i'll top out at 250~ mpg and that's it, no AC. I use the CC to keep my speed around 57 or so. when i'm not getting 9999 i show some HP and not zero gph. I can't remember what version SG sw i have, but it's a couple of years old. Any thoughts? thanks dave
Dave, Sorry. I have not send it yet. It's still a mystery to me as to when the SG decides to show 9999 or not. On my commute home today, it would show 9999 mpg. I'm pretty much convinced that this is just a Scangauge glitch. I'm still seeing consistently spectacular trip mpg's (59 mpg on the way to work yesterday with no traffic and 65.6 with rush hour traffic today) whether I get 9999 mpg or 250 mpg on the Scangauge.
