2009 Jetta ECU Flash 23H1/Y1

I assume that I am not the only one but I had the "recall" flash done before going on a road trip with my twin boys to look at colleges. Car has about 51K miles on it. Before the flash, I could get 50+ on the highway doing 60 mph and averaged around town 40+. Doing 70-75mph, I could easily get 45+. Now, after having driven over 1000 miles during my trip, the BEST I can get on the highway is about 41 (doing 60-65mph) and between 37-39mpg at 70-75mph. Normal driving will, most likely, be in the low to mid-30's If the flash was to truly take care of an O2 sensor calibration issue, it should not have that drastic effect on the mileage.

My concern is that the flash is something more to have that significant an impact on mileage. Anyone else experiencing the same issues? Tire pressure is 35psi and there have been no changes or mods to the car, other than the flash, that would produce this change.

Thoughts and/or comments?

wow, only thing I can think of with those original numbers is that you were measuring in miles per imperial gallon (4.5 litres) and now you're measuring in miles per US gallon (3.8 litres). just a hunch.

No changes here. I get the same crappy 38 MPG on a regular basis. The car does seem to shift better when it's cold or at low RPM's. It sucks you are experiencing that much loss in MPG's. Seems odd.

My recall was done several months ago, and I have seen no significant change in mileage. I still get about the same mileage I have always gotten (sometimes better, sometimes worse - depending on conditions). Some members have reported a decrease in mileage and some have reported an increase in mileage after the update. Therefore, my assumption is that it really has (had) very little effect on mileage. The difference you have seen could be caused by a wide variety of other factors besides the ECU update (like wind, traffic lights, regens, etc.). Only time will tell if it really made any difference. I seriously doubt that VW would release an update that actually significantly hurts mileage, but I'm not expert.

Have Fun!

Don

I've never met Security Guy, but we've spoken several times on the phone. Based on these conversations, and his posts on this forum, I'd venture to say that his analysis of his MPG change has already taken into account the variables mentioned above.

What is the possibility that a second "update" of the ECU could change things yet again? Computer Gurus: Any thoughts on that one?

egr computer modifications is my guess, keep it burning a different temp.

Biggest thing you'd notice is before and after EGTs and how they changed

egr computer modifications is my guess, keep it burning a different temp.

Biggest thing you'd notice is before and after EGTs and how they changed

as I am not a betting man (nor a computer guru) I will stick with my original bet. on my last tank, with no real change in driving habits or what not, I got a solid 6L/100 km which equates to 47 miles per imperial gallon or 39 per US gallon. in fact, on the last three tanks, one before and two after the ECU reflash, they are all about the same and I used the converter on this page to do the metric/imperial/US conversions. (this tank WILL be better as the 'fuel now' bell just went off at 899.8 km so I am going to go for my first 600 mile tank!) just for curiousity - how big is the reserve on the 09s?

TDIFred, your "original bet" (confusion about Imperial vs. US measurement) just doesn't apply here, unless Security Guy went for a VERY long drive, across Canada, etc. etc.

Don't you know that down south (from you!) we just don't have any reason to think/compute in Imperial units. We dropped everything "Imperial" 235 years ago.

I had mine done a couple of weeks ago and haven't noticed a difference in MPG.

thanks I know all about that 'tea in the harbor' (sorry, harbour!) spat. some of you folks still have a thing about the Royals though! (maybe because your tax dollars don't go towards paying for them - sorry off-topic!)
I was just throwing it out there as a thought/comment as per Security Guy's original post. it IS a possibility, remote I know, that his read-out was reading miles per imperial gallon. we all like to 'play' with the MFD.
now, he has not yet chimed back in, so until he does we really do not know. it is just odd and are the numbers being quoted from the read-out or from an entire tank?

Thanks for the replies guys! Definitely not mistaken Imperial versus gallons so we can rule that out. I will drive another 1000 miles or so and see what happens. There is definitely a significant change and I am hoping it will get better. Worst case, at my 60K mile oil change, I'll have it checked for other issues but seems strange that it started post-flash

We have put about 900 miles on her so far during our road trip and the mpg has been fairly consistent. Will put another 200+ on her today.

Bummed to hear about the change in fuel economy. I don't have near the miles you do & don't have a scheduled road trip until Oct. So far I'm in the no change category, commuting is exactly the same as before. Last tank was 40.6mpg (85% post flash). Lifetime is 39.9mpg = same/same. I have noticed the ability to accelerate after cresting a hill & better shifting @ low speeds.

securityguy said:

Thanks for the replies guys! Definitely not mistaken Imperial versus gallons so we can rule that out. I will drive another 1000 miles or so and see what happens. There is definitely a significant change and I am hoping it will get better. Worst case, at my 60K mile oil change, I'll have it checked for other issues but seems strange that it started post-flash

We have put about 900 miles on her so far during our road trip and the mpg has been fairly consistent. Will put another 200+ on her today.

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sorry to hear I was wrong but really not surprised. I think the reason my present tank is better than average is probably more highway driving (trip to Buffalo) and more use of cruise control.
I know with the reflash they alter the low idle speed so there is less likelihood of stalling and for that Iam thankful. One thing to note is tire pressure and I am glad you brought that up, I need to put some more air in mine.
Best of luck (what schools are you looking at? A buddy of mine just told me about a brewery in Morgantown. anyone know of it?)

I've got it! His engine is an OptiLube XPD junkie, and is going to require higher and higher percentages of the stuff to avoid the DTs!!

Sorry, my friend, I couldn't resist...

Did you fill up with at a station/brand you don't normally use?

On my trek to PDXFest last August, I was averaging an easy 45mpg at 72mph with A/C. Once each on the west/east segments I filled up with Conoco/Phillips 66 Diesel. These were obviously non-consecutive tanks. On each fillup, my mileage dropped to 38-39mpg. On each succesive fillup, back up to 45mpg.

I don't know what the issue may have been, but I'll definitely try to avoid Conoco/Phillips 66

After the re flash my mileage went down 4 to 5 mpg for the first two fill ups. On the third it did improve 1 to 2 mpg.Now I'm working on the fourth tank now.This is on done by pen and paper.I'm not shore yet if it a combination of the re flash and running the A/C and hot weather.


When I first got the re flash couldn't break 38 mpg on the highway it didn't any difference how I drove. The computer reading takes to long to change if you don't reset it.(example) You are driving in the city and the reading you get 33 mpg then you get on the highway and drive 30 miles the reading you get 38mpg.So is right wrong reading?


Today I did a test I reset the computer drove 10 miles pretty flat road made 2 stops traveling speed around 45 /50 at the end the computer read 53mpg.

That's OK Ed...I still love ya man

It was recommended on another thread that I have it reflashed. Might do that when I can make the time or just wait until my 60K oil change. One of the twins drove home and stayed a consistent 65mph and the MFD read 41...I used to get close to or over 50.

TDIFred - looked at UVA, Virginia Tech, William & Mary, VCU, UNC and NC State. All very good schools. One twin wants to be a doctor and the other an engineer like his old man

I need the better mileage to help pay for school

Mayor, I typically use either Shell or BP. My first tank was with BP from home and that got me 500+ miles. Second tank was with Marathon. I see no difference between tanks. Just got home and filler her up with BP at my local station.

The update has been like night and day for my engine. My mileage has improved slightly in local driving and my highway mileage is up significantly. On long trips, the car never had a 50+ tank average until the update. I'm still watching, but I haven't had the downhill shudder with the cruise on since, either.

...but could be due to your new brain too.

Nah, I still do a lot of shifting in tip because the DSG still lugs the engine in D.

tdiatlast said:

I've never met Security Guy, but we've spoken several times on the phone. Based on these conversations, and his posts on this forum, I'd venture to say that his analysis of his MPG change has already taken into account the variables mentioned above.

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Seriously...he's sharper than that.

securityguy said:

That's OK Ed...I still love ya man

It was recommended on another thread that I have it reflashed. Might do that when I can make the time or just wait until my 60K oil change. One of the twins drove home and stayed a consistent 65mph and the MFD read 41...I used to get close to or over 50.

TDIFred - looked at UVA, Virginia Tech, William & Mary, VCU, UNC and NC State. All very good schools. One twin wants to be a doctor and the other an engineer like his old man

I need the better mileage to help pay for school

Mayor, I typically use either Shell or BP. My first tank was with BP from home and that got me 500+ miles. Second tank was with Marathon. I see no difference between tanks. Just got home and filler her up with BP at my local station.

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Wow. I had the recall done at either my 10k or 20k service, never noticed a drop in mpg. I too can get well over 50mpg at a steady 65.

I have experienced the same thing. Had the reflash done within the last two weeks, followed by a long road trip. Got 7-8 mpg fewer than I had been getting on the highway and than what I expected. I called my dealer, who said the flash shouldn't really impact mileage. I'll keep monitoring to see if there are any changes.

I have experienced the exact same thing that Securityguy has, almost to the number. I went to the dealership and asked them to check if the ecm flash was done correctly. They said that there was no software version issues and that everything was as it should be. After a few weeks of driving and really getting pissed about the loss of fuel mileage, I went to the dealership and asked them to reflash my car back to the software version that I previously had. They told me "No way!" They said that the EPA would not allow them to reflash back to my previous software version. They told me that the new software version had some changes that were mandated by the EPA. They handed me some more hokum that the new software version also put a lock on the ecm that prevents it from being flashed back. I do not believe this for one minute but the end result is the same anyway because I do not have the ability to do it myself. The bottom line in all this is that I am getting worse (hand calculated) mileage after the reflash.

Why can't they simply re-do the flash? If you can demonstrate, with your records, that there is a substantial negative change in MPG, I would argue that the EPA wouldn't be happy with you burning so much more fuel!

I had similar result as OP. JSW was re-flashed at 01-Nov-2011 @ 28000 mi. Took car to dealer for faulty rear door lock and had them do the 30K service at the same time. Service Advisor told me about the software update and said it was to prevent the check engine light from coming on when it should not. I thought little of it and did not notice anything different...until Saturday. I drove to my mother's house 60 miles away. It's a straight shot all highway. I've made the trip many times. I typically get 46 on the way there, and 44 on the way back. On saturday I got less than 42 on the way there. That's lower than my lifetime average. On the way back I got right at 42. On the way there with the display showing something like 41.2 with about 10 miles to go, I mentioned to wife that mileage is markedly down for this trip compared to typical and that I suspected it may be related to the flash. The trip actually *hurt* the tank average. This is unheard of. I usually get around 42 average for my commute and the average always bumps up if I put the car on the hwy.

Also, I noticed the car went through 2 DPF re-gens in since the re-flash. I usually notice only about 1 regen every couple months.

That being said, the car seems to be running a little smoother and seems to have a little more power?!?. I'm wondering if the MPG hit might be related to the regen cycles. Perhaps the flash adjusted the start regen criteria, my car had a partially clogged DPF, and the new flash has been sending more fuel to the DPF until it gets cleared out?

Cheers,

Joe

tdiatlast said:

Why can't they simply re-do the flash? If you can demonstrate, with your records, that there is a substantial negative change in MPG, I would argue that the EPA wouldn't be happy with you burning so much more fuel!

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You don't actually think the EPA would apply common sense or logic to this, do you?

JKC_NC said:

I had similar result as OP. JSW was re-flashed at 01-Nov-2011 @ 28000 mi. Took car to dealer for faulty rear door lock and had them do the 30K service at the same time. Service Advisor told me about the software update and said it was to prevent the check engine light from coming on when it should not. I thought little of it and did not notice anything different...until Saturday. I drove to my mother's house 60 miles away. It's a straight shot all highway. I've made the trip many times. I typically get 46 on the way there, and 44 on the way back. On saturday I got less than 42 on the way there. That's lower than my lifetime average. On the way back I got right at 42. On the way there with the display showing something like 41.2 with about 10 miles to go, I mentioned to wife that mileage is markedly down for this trip compared to typical and that I suspected it may be related to the flash. The trip actually *hurt* the tank average. This is unheard of. I usually get around 42 average for my commute and the average always bumps up if I put the car on the hwy.

Also, I noticed the car went through 2 DPF re-gens in since the re-flash. I usually notice only about 1 regen every couple months.

That being said, the car seems to be running a little smoother and seems to have a little more power?!?. I'm wondering if the MPG hit might be related to the regen cycles. Perhaps the flash adjusted the start regen criteria, my car had a partially clogged DPF, and the new flash has been sending more fuel to the DPF until it gets cleared out?

Cheers,

Joe

Click to expand...

I decided to add a little more detailed information to supplement my previous post.

I had my reflash done on May 23, 2011. On May 24th I started on a trip from Issaquah, WA to Wisconsin Rapids, WI, where my parents live. I have been making this trip once a month since my dad was diagnosed with ALS in September 2010. I had always make my fuel stops at the same places on every trip, until the one in May. Previous to May, my first fuel stop has always been in Bozeman, MT where I have been staying overnight on every trip. This is 661 miles from my start point. On my stops in Bozeman I used to take roughly 13 - 13.5 gallons, depending on what time of the year it was. In the winter I used more fuel than in the summer.

However, starting in May, after the ECM reflash, I have never been able to make a fuel stop past Missoula, MT. Missoula is 459 miles from my start point in Issaquah. My car takes an average of 11 gallons of fuel when I fuel up in Missoula. That is roughly 41 MPG. Previous to May, when my car used to make it all the way to Bozeman, the fuel mileage was roughly 49 MPG.

The figures that I am citing here are rounded to the nearest 10th for simplicities sake. I have made this trip as I have said, every month since September 2010, so I have some very thorough records and experience in all 4 seasons.

When I showed my trip logs to the dealership to support my fuel mileage drop they concurred that I had enough evidence to support my claims. However; none of that mattered because they still insisted that my car could not be reflashed back to the previous software version.

Now that I have given more information to support my previous post, does anyone else have any supporting data that backs up their performance claims before and after the reflash?

I believe they are right about not being able to go back. Some people who have tuned their ECUs have had their programming deleted and the tuner couldn't easily put the tune back. Supposedly, the 2009-2010 MkV ECU supports advanced encryption, but they didn't have it turned on. The MKVI ECU has it turned on. From what I've read on here, the new ECU program turns that feature on.

Assuming they're overwriting the bootloader with one that can decrypt the new program, then yes, they wouldn't be able to go back, unless the bootloader supported overwriting itself with an older version, which would be a pretty big security issue. iPhones have a similar issue with the modem firmware. Once you update it, you can't go back without exploiting a flaw in the newer version (which possibly doesn't exist).