Beware of Dealer ECU Calibration MPG way down

I had an ECU reprogram performed last October after having an MIL code P0136 set. The reprogram was done as part of TSB EG038-04. When I picked up the Prius, I noticed two things. First, the HV battery was low (two pink bars). This tells me they likely didn't put the Prius on the battery charger (as per the TSB). It was too late to do anything about that, so I just noted it for my records. The second thing was that the average mileage for the tank was low (around 40 and I had been getting around 50). I think this was due to the way they test the cars per this TSB (i.e. drive the hell out of them for a few miles). Later tanks were back to normal, until winter (and the snowflake) set in. My tanks have been in the low 40s until the current one. I presently show 51.1 on the MFD. (Note: Temps here just turned spring-like a week ago.) Based on my observations, I don't think my car has shown any mileage degradation due to the ECU reprogram. Of course YMMV. Personally, I'd give it a tank, to see if the low mileage is an anomaly due to their testing.

G.

 

I had my recalibration done about two weeks ago and also noticed the engine running more and my average dropped a few MPG. After a couple of days it reverted to normal. I have no explanation and neither does my dealer.

We're all curious to hear what you are told.

 

This has been something that I had happen also to mine
not much we can do about it. If you don't have the MIL
on don't have the calibration done. It won't matter to anyone that got thier Prius this year because they all have the new calibration in them. We will have to wait till summer to see what exactly how much of a difference it will have.

 

Kyle, what do you mean, " if you don't have the MIL on? When i took my Prius in they told me that I need to have the brake light switch recall done,which I knew, and they also said I should have the "computer flashed"? Is that what we are talking about here? I told him I was hesitant to have it done since my car,36k on it now, has been perfect and I didn't want to rock the boat. But the service writer said, that Toyota recomends you get it done. Well since the old Prius tech left and the new Prius tech is in school, we put it off till my next oil change. But what do you think about, getting the computer flashed, if everything is ok?

 

Well, mine conked on me last November, so I *had* to get the recalibration.

Now that the temps are +18 to +22 C, the MFD claims I'm averaging 3.8-4.4L/100km (64-74 MPG Imperial Gallon depending on commute).

So there isn't any difference in fuel economy I can detect.

 

I just received the red triangle of death a couple weeks ago (driving in some rather wet weather, BTW), and subsequently had the ECU updated. I asked the service manager if the update would have a negative impact on mileage, and he was confident that it wouldn't (he probably didn't have a clue though).

Fortunately, I haven't noticed my mileage go down after the update.

 

This is the third time I have typed this and it is getting old & shorter each time.
1st No don't have it done if you have had your Prius for about 10-11 months or more & you are getting 52 MPG] 70 MPH.
2nd This TSB is to fix P3191 “Engine Does Not Start,â€
P3190 “Poor Engine Power,†and/or P0A0F “Engine Failed To Start.â€
3rd This is a easy .8 hr that can be started and left and go do something else.

 

I wanted to post it so I wont loss it again
I talked to an engineer at Toyota when this happened to my Prius he siad that he had never seen this before. I think that thy have seen it by now. Don't think any calls to Toyota are needed.
Finally the flash can't be undone or restored to a prev. date.

 

So I hope that as it warms up we can get back into the 50's
Also I hope that they find a better idea to fix this P3191 “Engine Does Not Start,â€
P3190 “Poor Engine Power,†and/or
P0A0F “Engine Failed To Start.â€
with out running the ICE more. Then Toyota will release a reprogram that will be a SSC and send a letter to every one like the 40D.

 

Kyle:

Thanks for the update.

Honestly, with the temps hovering +10C to +20C and no A/C, my fuel economy is averaging at least 4L/100km (70 MPG Imperial gallon). I haven't noticed any fuel economy loss at these temps.

However, I think in very cold temps (0 F or colder) the ICE does seem to run a lot more. Realistically, at -30 F or colder, it will run all the time. Some folks in cold climates have reported that the ICE does seem to run a bit more in extreme cold.

Let's face it, at 0 F or colder, especially reaching -40, all bets are off.

Jay

 

Thank You Kyle!!!!!!!!!!!!!!!

 

I had the TSB EG047-04 fix done and I noticed immediately that something was not right. The ICE kicked in waaaaay too much during my normal drives to work and even at speeds below 30. The battery would almost never assist unless there was real heavy acceleration. The same amount of pressure I used on the gas pedal before would now produce worse MPG. Also I was driving during warm weather conditions, 75F outside, so I know it wasn't because of cold weather. I swear something is wrong. Finally my battery level is higher than usual. It seems like it is getting filled up way too much and way too quickly probably because of the constant use of the ICE. It never did this before.


Also does anyone know if the dealer was suppose to replace the ECU? On my work order I see have an old part number 47070 instead of the latest one 47101. Also I can't tell what calibration they used because they did not put the Recalibration Label under my hood. Could a bad calibration be causing my problem???

TIA,
Eric

 

have you read all of the thread on this topic because I think you will better understand what is going on but in review This is a recalibration that has been going on for a year but is not something that Toyota is talking about. I can tell you that whatever they did is not going to help with the gas milage. I am as frustrated as all of you are. The part # changed every time the calibration was changed. As for any change in the calibration there is not been any change in what the calibration that they are currently using I just checked Today on a new PDI and it is still the same.
As for the labels they may of forgot or had ran out of them. I try to do it but I have to say it is not for the cust as much as it is for the Tech's in the future. Not a big deal I would never count on it to be there if I was the next one to work on your car.
So Yes it is a bad calibration that is causing us the problem but it is the same calibration that is used on every one of the new ones.
Also one other thing that I found to be of interest the
We started with 34702000 cal ID than came ****2100, ****2200,****5000,****5100 now we use 347052000. I got a used 04 with 34702100 in and did a test drive 70MPH at 70deg Today for 10miles it never got up over 50 for a 5min avg. So unless your last 5 digits are before 54000 you wouldn't have the 34702000 I belive that those are the only ones with the very first ones.

 

I made a post here describing the same situation from a battery disconnect.

I'm just wondering if anyone here ever found the exact relearn procedure to bring back max hybrid efficiency.

I know it has to do with driving but the Prius seems to be very particular about what initiates the relearn procedure. I can go months at a time without getting more pull from EV mode after a 12v battery disconnect until the ECU relearns.

My post linked above describes this in more detail.

If anyone has any info let me know!

Thanks!
Joe

Posted via the PriusChat mobile app.

 

Ever since I purchased and installed my new 12v battery (2 years ago) and got that Dealer ECU "adjustment" the only time I get 45 to 50 mpg is on a long 2 hour drive. City driving is now consistently in the 36 to 39 mpg range. I agree with your hypothesis TheLastMojoMo!

 

I am gearing up to do a video manifesto on this issue over the winter. There are actually many posts like this one. I have found 6+ posts that describe this exact issue coherently. And there are dozens more attempting to describe this issue but they don't have the knowledge or awareness about their Prius to describe what's happening effectively. They only notice lower mpg.

My Gen 2 Prius has been stuck getting City MPG's of 35-40 mpg for 3 years and 45,000+ miles now.

I have done everything in an attempt to get mpgs to return including replacing my Hybrid Battery with a Project Lithium one. There is nothing wrong with my Prius! No But the ECU's are throttling EV Mode output, reducing mpgs and there is no explanation for it anywhere.

This manifesto could be laying the groundwork for a massive lawsuit against Toyota. Either way I'm not going to stop until this Phantom low mpg mechanism is exposed and Toyota does something about it.

 

Was there anything on the service receipt about an "adjustment" being performed? What does it say exactly?

 

Wow! Even replacing the HV battery didn't change it? That was going to be my next move.