2 mile/gal projected loss of fuel economy with "modification" of 2009 Jetta why?

2 mile/gal projected loss of fuel economy with "modification" of 2009 Jetta why?

Subj: 2 mile/gal projected loss of fuel economy with "modification" of 2009 Jetta why?
related Subj: "modification" vs "buyback" 2009 Jetta TDI Sportwagon

I just received a "recall" package describing the "modification" for my 2009 Jetta TDI Sportwagon located here in California. The package describes the proposed "modification" as reducing fuel economy by 2 miles/gallon and I'd be interested in any engineering assessments about what exactly the "modification" fix does that reduces fuel economy and performance.

Also of interest although not directly related to fuel economy, VWcourtsettlement.com is reporting they will pay $21,136.73 if I return it on 4/2/2018 or if I do the "modification" on that same date a payment of $6011.73 but the "modification" is described as reducing fuel economy by an estimated 2 miles per gallon and also effecting engine noise and performance. I'm considering 4/2/2018 because that is the month the registration will be due along with a CA required "smog test" that I am presuming would be failed without the "modification." An earlier "modification" or "buyback" date 8/26/2017 results in a smaller restitution payment of $5906.73 for "modification" and $20506.73 for "buyback." So it seems like it is better to delay until shortly before the required "smog" test.

My understanding is that part of the fix is a bigger nitrogen oxide storage converter, and that the fixed software will refresh that converter more often, by injecting extra fuel to reduce the stored nitrogen oxide to nitrogen. So the car uses more fuel than before to put out less NOx, at the price of putting out more CO2. You pick your poison (or rather, the EPA picked it for you).

I don't think anyone will know for sure the cause of the FE loss until cars are fixed and folks get to see the hardware and software changes. But I bet the loss is from fueling map changes, retarded timing to reduce NOx, and more after combustion dosing to improve the operation of the DPF and Cat. But that's my guess. Honestly, I don't think the number is that significant. Again, we'll know better once some fixed cars are out there accumulating miles.

So you're going to turn in your TDI, Then you buy a gas burner which gets less Mpg and then you b i t c h about the worse Mpg.

MY 2014 JSW got the VW fix last week. So far I've put about 400 miles on the car since the fix and can safely say that it has not lost any power and actually feels like it has more grunt in the mid range. I have the 6 sp manual transmission and drive pretty aggressively and I'm more than pleased with the results of the fix. I don't know yet if I've lost any mileage, but if so it's minimal. Certainly not enough to worry about, and since I'm going to have a Malone tune reinstalled my mileage should go back up where it was.

Wish I had an eight year old car I could sell for $21K. Hard to believe.

What is a "Malone tune" and why does it improve TDI mileage?

skromfols said:

MY 2014 JSW got the VW fix last week. So far I've put about 400 miles on the car since the fix and can safely say that it has not lost any power and actually feels like it has more grunt in the mid range. I have the 6 sp manual transmission and drive pretty aggressively and I'm more than pleased with the results of the fix. I don't know yet if I've lost any mileage, but if so it's minimal. Certainly not enough to worry about, and since I'm going to have a Malone tune reinstalled my mileage should go back up where it was.

Click to expand...

Here is their link:

http://malonetuning.com/

Malone Tune options compatible with the emmissions fix?

Which of the "Malone" tune kits will you install? The website describes three, the "MT1756 220 hp max" being one, but others with 250 hp max, and 280 hp max. Does increasing "hp max" improve fuel economy even with gentle conservative driving habits?

Lightflyer1 said:

Here is their link:

http://malonetuning.com/

Click to expand...

Which do you think is the best for someone who do long drives weekly?
______________________________________
Towing Arlington VA

I don't think they promote their product for economy (fuel mileage). Some have reported gains and others not. If all you are looking for is economy I wouldn't buy.

walterwood said:

Which of the "Malone" tune kits will you install? The website describes three, the "MT1756 220 hp max" being one, but others with 250 hp max, and 280 hp max. Does increasing "hp max" improve fuel economy even with gentle conservative driving habits?

Click to expand...

I think you might be on the wrong page, past stage 3, which is 180-190WHP, we list varying results http://malonetuning.com/ecu-tuning/audi-volkswagen/tdi/20l-cr-tdi


Other than the VE platform we don't advertise fuel economy gains, without deleting emissions components for race use. With that said, the recent changes to injection mapping to reduce NOx would likely affect mileage, so I wouldn't be surprised to see 1-2 mpg restored from a tune. It's too early to tell and the results vary so much that it will be hard to get finite data. That's also assuming you can keep your foot out of it/drive the car identically. Of course, to make more power you have to burn more fuel, so driven harder the car will burn more fuel.

Most people drive their cars harder once tuned and don't notice a difference in mileage. When we're talking a 25%+ power gain in most cases that's worth every penny. If all you're concerned in is getting from A to B for as cheap as possible, the $500 would be better spent on fuel.

Of course my experience with my 2002 Jetta TDI may be different to the newer TDI's.

But my car had the rotten 4 speed automatic and stepping on the accelerator was like stepping on a wet sponge. Any small hill the tranny would shift down.

First mod was to put in .205 injector nozzles instead of the factory [.155] nozzles. Big difference in get-up and go and even better Mpg since the
d a m n tranny didn't have to shift down so much. If I remember the .205 were factory in the 5 speed manuals.

Second mod was to get a tune done, now there was an even bigger difference and a Mpg improvement too.

Had it dynoed back then and the out put was 128hp up from 95hp and the torque was also quite bit higher at about 185lb, up from the original 155lb.

What the OP needs to know it is NOT the horsepower in the TDI, it is the TORQUE which makes the difference!!!

Gasser's develop their Hp at high Rpm's. Diesels get their almost maximum power at around 2,000 Rpm.

When all the VW fixes are done I'm getting the Malone tune and DSG tune.

Mileage degradation

My coworker had his 2015 Jetta SW modified 2 weeks ago.
He drives his manual 6 speed like a man possessed to get every mile out of his tank of fuel. After the mod he is telling me that he's gone from the high 40's mpg to @37 mpg. That would be a helluva lot more than 2 mpg degradation. Neither of us are new to VW diesels.. We both had Rabbits in the 80's and picked up Jetta's some years later.. His 2009 TDI is still running strong with 390k on it!
I take my 2012 TDI SW in tomorrow for the "fix". I don't get the high 40's he sees but I do average @42 with the DSG so it'll be interesting to see how bad the mileage hit is on this unit.

Cheers,
TLW

I've been examining the new software in some depth.

Probably the reason for the expected decline in MPG is due to much higher egr rates than before. There is also retarded timing at mid-low loads and *greatly* increased rail pressure at part load. Also, timing is retarded at some time compared with before.


So the way they got the nox "numbers" is by cranking up the egr. A lot. The problem with that, though, is increased soot production... thus the increase in rail pressure to offset the potential increased soot from egr.

Why didn't they do that in the first place, without all the dieselgate hoohah? Well, here's my thoughts on that. The engine noise is more "dieselly" with more noise and clatter under some conditions. Traditional TDI guys don't mind. (in fact we like it) But the mass mainstream camry buyer types that VW was trying to appeal to for increased market share would be more likely to wrinkle a nose at the sound of a clattery diesel.

SO there you have it.

Kerma, this is the 2009-2014 ECU firmware you are talking about? Asking because the previous poster threw a 2015 into the discussion.
If it is indeed the gen.1 firmware update you looked at: what are they doing about nitrogen storage cat regeneration? How often does it run now, with the new larger storage cat?

yes, cjaa/cbea

nox regens are designed to trigger concurrent with DPF regens. It manifests as a "stage" of "the" regen. just like before. You won't know the difference of which "stage" of regen is actually occurring at any one moment unless you watch all the egt readings to see how they change in relation to each other as the regen(s) proceed. The internal models are tweaked to make sure the dpf is always the limiting factor for this. The whole thing is meant to be transparent to the driver. You probably won't notice anything different from before the fix, just driving around.

TDI fuel economy acronyms and abbreviations

Is there a glossary of TDI acronyms and abbreviations used on this forum? If "a little reading" is suggested, please give the specific reference.

KERMA said:

yes, cjaa/cbea

nox regens are designed to trigger concurrent with DPF regens. It manifests as a "stage" of "the" regen. just like before. You won't know the difference of which "stage" of regen is actually occurring at any one moment unless you watch all the egt readings to see how they change in relation to each other as the regen(s) proceed. The internal models are tweaked to make sure the dpf is always the limiting factor for this. The whole thing is meant to be transparent to the driver. You probably won't notice anything different from before the fix, just driving around.

Click to expand...

http://forums.tdiclub.com/showthread.php?t=193175&highlight=acronym

There you go. The search function works as well.

KERMA said:

yes, cjaa/cbea

nox regens are designed to trigger concurrent with DPF regens. It manifests as a "stage" of "the" regen. just like before. You won't know the difference of which "stage" of regen is actually occurring at any one moment unless you watch all the egt readings to see how they change in relation to each other as the regen(s) proceed. The internal models are tweaked to make sure the dpf is always the limiting factor for this. The whole thing is meant to be transparent to the driver. You probably won't notice anything different from before the fix, just driving around.

Click to expand...

Thanks Kerma, that is very interesting, also the 'just as before'.

So, if I understand you correctly, you are saying that while the engine self study guide made it look like NOx regenerations are happening way more often than DPF regens, in reality the old ('dieselgate', cheating) firmware never scheduled them outside of DPF regens? And that the new NOx cat is now large enough to absorb NOx for the full duration between DPF regens.

That doesn't sound so bad. My DPF regens are now (75k miles) happening every 160 miles or so, a little more frequently than in past years. I should probably plot the distance between regens, since I make Torque save all those logs.

Kerma, if you don't mind: What are the EG temperatures for an NOx regen, as compared to a DPF regen? EGT 4 higher, and EGT 3 lower, or something like that?