Change in behavior on Instant MPG Meter

With only six thousand miles under your belt, you should still be looking out the window at the road and not trying to do advanced diagnosis of what the Prius HSD is doing.

Everything you have said 'could' be normal . . . depending on the situation.

. . . could be normal if . . . the car isn't yet warmed up.
. . . could be normal if . . . the car is traveling at low speed.
. . . could be normal . . . often.

Don't worry about it.

IT sounds normal.

Just drive it.

 

Try filling up with Shell gas next time. When I get a lower-energy tank of gas and/or a high level of ethanol, I will see this behavior. When I fill up at a Shell station, my mpg bar always as a rule shoots up to 100 mpg faster when I let off the gas. It also seems to stay there longer and not come down as fast when I lightly apply the gas pedal again. If I ever have to fill up at an Exxon or Chevron, the mpg bar struggles to get to 100 as fast. It seems to lag and take almost a second or two longer.

FWIW, once I filled up at a Kroger that had E85. Their normal E10 gas pumps didn't say, "may contain UP TO 10% ethanol" like other Krogers. Instead they said, "CONTAINS 10% ethanol". I got the worst mileage, acceleration power, and mpg bar response times ever in the 34K miles I've driven so far.

 

It's not like the gauge is analog and will go out of adjustment. In a year and a half reading posts here, I have not yet heard of someone's mpg sensor giving false readings... maybe you could search for that, though.

I think your gauge is just reporting what the car is doing. Since no error codes show up, all fingers point to an external factor. I mentioned fuel because it is always your biggest variable to mileage and performance all_other_things_being_equal. (That is, same routes driven, same external temperature, same driver, same driving techniques, etc.)

Another possibility, you could have put in mid-grade or super by accident. The guage will really show a struggle for readings above 75 mpg with 92 octane gas.

 

My prius has 125K on it and I am second owner having put on 30k of those miles. Just recently I unplugged the standard care battery in the back to do some work on the headlamps. Now the Instant MPG has this strange lag. It was very responsive until now. Now it jumps to a number and holds there for much longer then jumps either way up or way down depending on my driving.
The fuel is the same. The only thing that could have affected it is the diconnecting of the battery. I think this might be a calibration thing. There Could be a fuzzy logic circut here that has to relearn the curve. I am betting that this behavoir will smooth out as I keep driving, but that is just a guess. If It stays like this I will be very disapointed.
Regards,
Patrick

 

Welcome to PriusChat. A Prius driving Northern Californian named Patrick. You must be one cool dude! And if you are driving a Salsa Red, it's confirmed!

After having driven your Prius for 30,000 miles, I'm hoping you noticed that the instantaneous MPGs aren't really instantaneous, AND instantaneous MPGs will jump wildly up and down for the first few miles after a gas fill-up.

If this somehow erased some fuzzy logic, I'm fuzzy on that one.

 

I had a Honda Insight for 7 years before that. Can't beat that comeback.

 

The Grand Mufti says:

Do not say your tire has a flat. You are not worthy or capable of that observation until you have driven 100,000 miles with your Prius.

 

I am not sure why a come back was required?

After 30,000 miles of fill ups my Meter never behaved as slow as it did after I reconnected the battery. After about 100 miles the meter gradually returned to normal. A fuzzy logic Circuit is a plausible explanation for the meters aberrant behavior, but it is just a guess. Certainly not cause to bring out egos and be insulting.

The fill up issue is gone within a a mile or two of of driving, at least for me. This was something different, hence my comment.


Patrick