Did reprogram affect your mileage?

From what i remember hearing " back in the day " ('04) is that the computer system adjust to the way you drive.. maybe you just need to drive it more and the system will re calibrate itself. In the mean time i suggest http://www.toyota.com/html/hybridsynergyvi.../fall/mpgs.html taking a look at that page.. you sound like you're getting good gas mileage but there are a few tips on that page. I'm about to have my reprogram done today.. i wonder what it will do to my mpg....

 

I've seen more trips get 50+MPG after the 50P than before. Last weekend, I averaged 50MPG over maybe 230 miles until I felt like hitting the highway at 70MPH and lost a couple.

Perhaps tire wear holds the car back less, but the rain traction is still great...

 

My experience is quite the opposite. It is easier for me to get into stealth and/or glide and I took a slight bump up. I am able to get in and stay in stealth even up hill when the ICE would generally cut in.

 

Yes! Same here. Very disappointing. Last winter I averaged ~48 mpg, Since my recall reprogramming this past fall I've been averaging no better than 44 mpg.

This is the recall that addressed the problem of the gas engine stopping and not restarting during travel, forcing folks to use electric only to get off the road safely (I read that this happened to ~32 cars here in the U.S.).

Glad to have the improved safety and reliability, but it seems that this is a pretty steep price to pay to be protected from an event with a very low probability of occurrance.

 

If anything it has improved mileage and driveability for me.

 

I've plotted every tank in the 25K miles on my '05. Lately, I had been averaging 47, and it dropped to 44-45 after the reprogram (same routes, same weather). It has crept back up, but not quite to 47. I expect it will "relearn" in another tank or two, and return to normal.

 

I have not noticed a drop or increase that may have been attributed to the reprogramming. I think my drop has been mostly due to the drop in temp and the use of oxygenated gas here. Although my last two tanks according to the MFD have been at 59.5 MPG so it is probably around 56 MPG.

I got mine reprogrammed because I had a few times where it would not turn on or two instances where it would not turn off. I had to hold the power button for a min for it to finally do something. Although not sure if it was due to Mexico. They are not regulated by our regulations so every now and then they will pick frequencies that disrupt everything here (car alarms, garage doors, etc).

 

I had a very similar experience after the recall 50P ECU reprogram was done 3 months and 2.5K miles ago. My mileage dropped from 42-43 town/50-60 highway to 38-40 town and I haven't been able to crack 50 on the highway. Not a huge difference and I'm sure the dealer would deny there is a service issue so I haven't pushed it. I was hoping that the car would "reset" itself after a while but I'm not seeing much, if any improvement.
I would swear that it doesn't coast as easily and the ICE starts up with less load than before, so now it's a little harder to stay in electric mode than before the reprograming. Also, sometimes the ICE runs on and on whereas before in the same situations, it would shut off.
BTW, I have 3 winters and 43k miles driving on 2 different Priuses and I pay attention to what I'm doing so I'm pretty sure this is actually something related to the reprogramming. It's enough of an issue that I no longer leave the MFD screen on the 5 minute bar average - I switch to the energy management screen so I won't have to look at my dismal average.
Doug

 

"I heard from my dealer that the real reason those cars stopped were that the drivers were out of gas and the car will not let you drain the battery all the way. Any idea if that is true?"

This is nuts. Dealers like to make stuff up when they don't know the answer. Yes, some were really out of gas, but many had gas but failed to start. Has nothing at all to do with battery charge.

 

OK, I'll agree with that.

However, the ability to coast at 100MPG does not directly relate to maintaining MPGs around 50. That will likely cut into people over 50 a lot more than it affects those of us who rarely see an average over 50 except on a 'highway'.

For example, I managed to get home (9 miles) fresh from a fill-up a week or so at over 60MPG. This is not normal, and a few days later it was down to my usual 47MPG or so.

So if I'm coasting home (nearly 3/4 mile mostly downhill) and the reported MPGs aren't 100 like I used to see but 60-70, it's really no big deal to my average since anything over 47 will usually raise it.

I do seem to have plenty of 75MPG 5-minute periods and even a 100 every now and then under the right conditions, but again only when I'm away from home...

 

Every time I take my 05 Prius in for a 5K checkup, the gas milage has gotten worse.

I have also had large discrepancies between the cars calculation of MPG and the manual calculation based on the miles driven divided by the gallons added to the tank. The diff between the two methods is over 20 MPG. Piss poor. You simply can not trust the fuel gauge on the dashboard.

 

"However, why would Toyota mess with the controls over gas engine timing (i.e., making it easier to trip the engine on and harder to just use electric motor/battery during driving) if the issue was that cars were having problems starting? "

I can no longer cite my source, but I don't think that is what the reprogramming does. I believe it merely reduced the "hair trigger" under which the car previously would "give up" starting after a too-short duration of trying to start the ICE.

For example, suppose it used to allow 0.25 seconds to start after spinning up and "lighting" the ignition, valves, and injectors. But it took 0.30 seconds SOMEtimes. On those rare occasions, the car figured there must be a mechanical problem with the ICE, since it took too long to start, and FORCED a shutdown, leaving you with EV only. (But if you shut it off, and went to READY a few times, the "restraining order" is lifted, and you could drive on as if nothing happened.

By lengthening the duration to, say, 0.4 seconds, the reprogramming will avoid the "false alarm shutdown." The actual conditions under which the ICE starts up are not changed, just the "patience" of the car as it waits for the ICE to fire.

 

"The diff between the two methods is over 20 MPG."

If true, take it to the dealer, it has a defect.

Unless you are only putting in a couple of gallons (and thus failing to auto-reset the mpg tracking), you just can't see this much of a discrepency on a consistent basis. Uneven fillups can cause errors, but you make it up on the next tank. If your long term average is 20mpg off, then there is a malfunction.

 

Just to add to the data. No noticable change for me. Averages about 47-51 mpg before and after.

Wondering if dealers did something wrong with the updates for certain people that didn't cause a whole system failure (like the ECUs frying) but instead these latent problems that people are experiencing. You would think that there would be error codes lighting up if this were the case, though.
One thing to check if you also had an oil change or tune-up at the same time is to see if they overfilled your oil. Some have reported a drop in FE due to this. Hope you can figure it out.