Latest Software Update Safety Recall Resulting in 8mpg less...

Have you measured or math modeled either one? I did because I am experimenting with over sized tires on our 2003 Prius and have actual numbers. But we can also math model the new tires on that car.

I'm running 195/70R14 Yokohamas which according to Tire Rack specs:

• 10/32" tread depth, 834 revs/mile
• 1 rev = 1/834 mile = 6.3309 ft/rev
• effective diameter = 6.3309 ft / pi = 6.3309 / 3.141592 = 2.015188 ft
  
• lost radius from tread wear = (10-2) / 32 = 0.25 inch = 0.020833 ft
• lost diameter = 2 * 0.020833 = 0.041666 ft.
• worn diameter = 2.015188 - 0.041666 = 1.973522 ft
• worn distance per rev = 1.973522 * pi = 6.1999 ft/rev
• worn rev/mile = 1 / (5280 / 6.1999) = 852 revs/mile or 2.2%

We instantly have the 1/3d of the estimated 6% low MPG. Then add the tread flex losses and we're within spitting distance of explaining the reports of inaccurate, indicated MPG.

There is a reason why real MPG metrics are done with a 5th wheel:


Bob Wilson

 

I agree, roughly: to start with a brand new tire with an OD of 25", and then scrub 1/4" (8/32") of tread depth off , you've theoretically increased revolutions (per any given distance) by 2%. But OTOH:

1. People are going in for the recall, and noticing a marked drop in mpg on their next tank. Tire wear is not a likely culprit here.

2. Obviously tire wear when comparing two vehicles could still be a significant factor. If you swap tires between the two vehicles, that'll confirm or rule out the factor. And: you would need the good mpg car to be running on brand new tires, and the other running on near-bald tires, to achieve a max 2 %. I just think we're looking in the wrong place.

 

I'm OK with looking at other things provided there are some sort of metrics or benchmark to reference. So far in this thread there has been only one credible benchmark, the maximum acceleration onto a freeway ramp. But it is difficult to replicate as we don't have an accurate, technical description to find equivalent ramps.

I've offered cruise control, speed managed, 10 mile, benchmark data but no one has taken their car onto local roads. There have been a lot of 'fingers lifted' to complain but little 'real life' testing. PriusChat posts are not facts and data, going out and hard data requires putting the computer down and going out to captures real data on the road.

Bob Wilson

 

If you mean removing the power at the battery... yes I did.

Also a clarification on the new tires on my Prius. The MPG drop happened immediately... the day the recall occurred and called to notify the dealer of the problem (which they have no record and don't make notes based on phone calls). They told me to wait until my next service (which I now regret). I changed the tires two months later (with a fuel efficiency rating of 9 out of 10), and they are saying that they can't use any of my data due to the different tires than the original ones. They are also unwilling to redo the upgrade, unless I pay for it because their standard diagnostics do not show a problem.

 

The car's calculated MPG is a good indicator, and how I saw the drop immediately. It is very true that the car calculated MPG is overly optimistic and from my history of tracked fill-ups the car calculation over states the actual millage by 5.5% (or only gets 94.7% of what the car calculation claims).... but I think that is the subject of a different thread.

 

Just be aware that the fuel efficiency rating you are referring to is only comparable to other tires from that manufacturer and in that same exact tire category. I.e. the Michelin Primacy MXV4 is rated at a 9 in FE and the Energy Saver A/S is rated a 10. You would think these two tires should be similar in efficiency but they are not even close because they are in different categories. One is a luxury touring tire and the other is a standard touring. People generally lose about 4mpg when swapping from the OE tires to the Primacy MXV4 despite it being rated so high in FE by Michelin. In contrast, people generally gain a couple mpg when swapping from the OE tire to the Energy Saver A/S.

 

Larry,

Assuming you didn't get any other services such as an oil change on the day of the software update, I would take it to a DIFFERENT DEALER and pay the 1 hr or so labor to have the update applied again. I think this is most time and cost-effective for you after you have checked the basics:

1. Tire pressures, which you have already checked
2. Oil not above max on the dipstick and is of the correct weight (0W-20)
3. No drag on the wheels due to frozen calipers, etc.

 

Several have taken cars back to same dealership for reapplication of the update. They're not averse to it I think.

 

You are perhaps correct unless it's a rogue dealer you are dealing with that wants to "prove" they did the update right the first time at your expense Besides, why would you want to try again the same guy that you suspect may have failed once already?

 

We had both of our Priuses done at the same dealer and my wife's didn't show any change after. I see that there are people that got it reapplied, but I am not seeing that it fixed the issue. Did it fix it?

 

Perhaps it was done by a different tech on your wife's car and a rookie on your car? If it's the same tech on both, perhaps (s)he missed performing a step, software or hardware such as pulling one of the fuses out before applying the update? Perhaps there's a bug in the software that does the updating that causes these issues sometimes?

Dealers aren't necessarily known to be meticulous. I had an oil over-fill one time, wrong weight oil another time, etc.

IIRC, it got fixed in at least one case, perhaps if you poured over the threads on this site you will find it, but unless one is trying to write a research paper or thesis out of this, if I were you I would start with a reapplication of the update at a different dealer after explaining to them why you are getting it reapplied so they make sure to use their most experienced and meticulous tech on this, perhaps even let you watch the reapplication. Should be one hour of labor ~ $100.

 

I took it in (for my 30K service) and asked them to reapply the update. They said I was at the latest version and that they did not have a procedure to reapply it. So I struck out there. The service rep is having them create a new case to send to Toyota, and requesting that they are taken out of the loop, since I had done everything that was requested with the dealer under the last case and that I was still not happy (it didn't seem like passing the buck... there is just nothing else they can do as a dealer based on the diagnostics, procedures, and information they have). My next action is to call Toyota again, and create another case with them to tie with the case from the dealer, and hope that Toyota corporation can do something.

One new odd thing was that the car did not notify me that I needed my 30K service, which it is supposed to do (I was over 1K past due). While not probably related, it could mean there really is something wrong with the update that caused it, or the person doing my update didn't follow procedures correctly and reset my service counter when it shouldn't have been, and therefore the application of the update is suspect.

 

Is it the same dealer that originally did the update or a different one?

 

Someone else here mentioned similar, just in the last day or two.

Too bad you struck out with the re-update. Owners are really in the dark..., maybe some who were told the update was redone infact were just BS'd by the service writer? Who knows. I hope it gets resolved.

 

At least our airbags aren't going to explode in humid weather.

 

same

 

I would try a different dealer; seems like you missed my earlier post recommending going to a different dealer. It's a total BS that a firmware update can't be reapplied; they are just unwilling to admit any errors on their part should the reapplication fix the issue for you; at least they didn't charge you and then bluff that they reapplied the update, so I would be happy about that. I work in computer software and updating the ECU firmware conceptually shouldn't be any different from updating the firmware on your network router or the BIOS in your laptop.

 

I am not convinced it is the dealer, and seems to be more that Toyota Corporation requires adherence to their procedures, and rely on the Toyota provided diagnostics to determine if there is a problem. I too worked as a SW engineer and yes re-flashing should be easy and repeatable. I also know there are bugs and things that are not always detectable in current SW, but that seems to be completely lost of them, even though they know there are recalls and updates for that exact reason.

As instructed by the dealer... I did call the Customer Experience number yesterday (1-800-331-4331) to open yet another case and they said they had no way of searching if others had the problem, or if someone was looking or trending on this problem. It seems like a basic function that they should be able to say others have the issue or that Toyota is even looking at it. I was told that the dealer should not of handed me off to call them, as they can do nothing to fix anything... it is the dealer's responsibility to be the buffer for them. I just want my car back to operating like it did before Toyota physically did the recall (which is also way closer to their advertised MPG, which I got before). This appears to be too much to ask, as I should be happy that I get more than 38 MPG, which is all I am supposed to expect.

 

I got a call back from Customer Experience, who had gone back to the dealer, and since there is nothing showing up on diagnostics and nothing is in published service bulletins... there is nothing wrong.... They recommend I pay for another dealership to run the same Toyota diagnostics that doesn't show the problem... so it won't do any good. They will not tell me if others had reported the problem or that they were looking at it, because it would be Toyota Proprietary... but the have no problem having me pay another dealership to run diagnostics, even if they knew that I was wasting my time and money. We know several people have reported it based on this thread. As for the Service reminder not displaying.... they say it must have been a mistake made by the tech that did my upgrade, and while they don't know that for sure, they are positive the tech didn't do anything else different from the procedure, made a mistake, or that a corrupt load caused it. I guess 38 MPG and above, even if a large drop occurred the day of a Toyota service is fine with them, and there is no problem. Even though there is a large discrepancy between mine and my wife's cars millage after the recall... They have refused many times to take my car and any of their cars (used, rental, new) on the same route to verify the problem, and that the diagnostics catch those types of problems. I don't think they want to have to acknowledge the problem, and that would do it.

 

Are any exchanges by email? Link some of the priuschat threads?

Gotta say tho, corporations are dismayingly glacial, it would be a HUGE brownie point if they stepped up on this, bucked the sad trend.

FYI ours had no drop in mpg post update, but I don't doubt your case. It's seems a crap shoot, with a chance of something screwing up in the process, leaving half broken programming.