I recently took my 2004 Prius in for the 15,000 maintenance, and while it was in the shop they did the recall repair for the problem some Prius have had stalling. They reprogrammed the computer, and now my mileage is no where near what it was before. I used to average 42-45 in town, and now I'm only averaging 32-33. What can I do? (I had never stalled, and didn't request this reprogramming.)
This has been reported several times on this site. You will notice unusual charging behavior and lower MPG for a few tanks as the system retrains itself. Mine just got it's best mileage ever, so the reflash didn't have any lasting effects. Remember, weather and driving conditions make a big difference also.
the HV ECU retains driving history data to improve MPG based upon your driving patterns. takes 3-6 weeks to accumulate when purged.
Hey, that's the first time I heard of this. Sounds pretty cool! Not saying I don't trust you galaxee, but is there a source for this info?
clarification from DH, now that he's back: the biggest change you'll see in MPG is because the HV ECU uses this data to improve the MPG readout accuracy. however, there are parts of the car (HV ECU and others) that do learn your driving habits. he says, "but that doesn't mean you can drive like me and expect good mpg" :lol: the HV ECU does to some extent adjust to your driving habits. all cars do have adaptive programming to tailor the performance, etc to the individual driver. this changes the shift patterns and other performance items. obviously shift patterns don't apply with a CVT but just to get the idea across... here's a situation he's seen. a guy let his son take his car for a weekend trip. when the son brings the car back, it's acting differently. dad brings the car in to the shop, saying something's wrong with the car. nothing is actually wrong, it's just that the car has learned that the son likes to stomp on the gas. a battery disconnect or ECU reflash will erase your saved history data and the car needs to re-learn things a bit. hope that makes things more clear.