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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW Passat Family (NMS and B7) TDIs (2012+)

VW Passat Family (NMS and B7) TDIs (2012+) Discussion area for the 2012+ Passat TDI (North American and rest of world versions versions). The North American model was previously codenamed NMS (New Midsize Sedan) and the version the rest of the world gets is sometimes referred to as B7.

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Old July 11th, 2017, 19:26   #16
KERMA
 
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Quote:
Originally Posted by BKmetz View Post
'internal model' is an interesting term. Can you expand on that?
A little.

In the interests of brevity (and competition considerations) let's just say this. There is a simulated (calculated) soot number and a measured soot number. You can see these in adv meas values in vcds. The measured number comes from the d/p sensor. The calculated number is based on a complicated internal soot simulation model. There are a series of conditions (temp, pressure, throttle, etc) and software application switches that decide when each holds sway. The details of that mechanism are not important for this discussion. But in the CR ecus I've seen it appears that the measured number is pretty much intentionally "turned off" for purposes of deciding when regen should occur. You can see this yourself... If you ever monitor both measured and calculated, you will likely see the calculated generally keeps going up and up at some rate, while measured can fluctuate up and down pretty notably (with passive regen for instance). In our GSW the regen happens pretty predictably when calculated soot reaches ~24 g. (earlier cars the number was lower like 18g) Measured soot could really be anything when regen happens. (unless it gets too high) But the calculated will be like clockwork. The soot simulation model is fairly conservative compared to what physical soot is under most conditions, and the model doesn't appear to consider passive regen effects in any significant way. Regens other than the DPF *are* considered in the model though, and these may not be noticed if you are only monitoring pre-turbine EGT.

There is also some conditions of engine run time, miles since last regen, fuel used since last regen, and a couple of others, but those are switched off in the ecu I have checked. So its pretty much all on the soot simulation model to trigger regen.

hope that helps
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Old July 12th, 2017, 03:37   #17
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KERMA, I have to ask, since you seem so familiar with the EDC17's internal workings as applied to the VAG CR engine, did you or any of the other tuners notice the "cheat" before the cat was out of the bag? Just curious. Seems like it would have been obvious to those that know what they are looking at.

Related: do you know anything about Mercedes-Benz' SCR logic? As in, how would a "low DEF usage" DTC be gathered? I assume SCR is essentially the same across brands.
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Old July 12th, 2017, 09:08   #18
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Not familiar with the MB. Not enough time in the day. I am hyper focused on VW TDI and always drilling down deeper.

I think I posted something in the mega threads about how I believed the cheat worked. It was somewhat obvious to find once it was known to be there. It doesn't really change what a tuner does, just a matter of intellectual curiosity for me. Those ecu are pretty complicated as it is, for example more than 20 turbo boost maps in a CJAA for the various operating mode states. A few regen states, Several preinjection states, high altitude versions of each, etc and so forth. Even the very rudimentary "shallow" tunes out there should cover all those operating modes anyway. It's kind of like doing 20 tunes for each ecu if it's done right. So "typical" tuning method is not terribly affected whether the cheat is there or not.

Interesting to note that the "fix" sw versions have notably fewer maps for everything. because the "alternate mode" maps are just gone. This is remarkable, because typically Bosch keeps unused functions in the ecu, but just turns it off if they have to, with a vestigal map as a place holder or something like that. But this is different- it is completely gone. It's quite a remarkable departure from what was the normal practice.
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Old July 12th, 2017, 09:49   #19
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Intellectual curiosity is a good way to put it, and I am in the same mode with that. So how does SCR equipped VAG engines work? Are the pre and post NOx sensors calculating DEF usage by the reduced value across the substrate in the deNox catalyst? They do not show "real" DEF tank levels, so it cannot calculate it that way.

I have had a few CATA 3.0L engines with failed deNox catalyst faults.
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Old July 12th, 2017, 15:39   #20
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Quote:
Originally Posted by KERMA View Post
Also, the Polar FIS works with the passats. Super cool, turns your MFA into gages.

VCDS needs to be one of the hex+can or newer ones that use the "smart dongle". The older cables won't work.

Interesting what BK said about regens but FWIW those cars base their regens on the internal model not the measured D/P.

Mickey come by sometime, I can give you a guided tour of your car's stuff if you want. And yes your car does have throttle(s).
I assume by "come by" you mean "drive to Colorado"? Which I'm not against doing, just for the road trip. I'd rather wait until I have the money for a DSG reflash.

-mickey
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Old July 12th, 2017, 15:41   #21
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Quote:
Originally Posted by KERMA View Post
Not familiar with the MB. Not enough time in the day. I am hyper focused on VW TDI and always drilling down deeper.

I think I posted something in the mega threads about how I believed the cheat worked. It was somewhat obvious to find once it was known to be there. It doesn't really change what a tuner does, just a matter of intellectual curiosity for me. Those ecu are pretty complicated as it is, for example more than 20 turbo boost maps in a CJAA for the various operating mode states. A few regen states, Several preinjection states, high altitude versions of each, etc and so forth. Even the very rudimentary "shallow" tunes out there should cover all those operating modes anyway. It's kind of like doing 20 tunes for each ecu if it's done right. So "typical" tuning method is not terribly affected whether the cheat is there or not.

Interesting to note that the "fix" sw versions have notably fewer maps for everything. because the "alternate mode" maps are just gone. This is remarkable, because typically Bosch keeps unused functions in the ecu, but just turns it off if they have to, with a vestigal map as a place holder or something like that. But this is different- it is completely gone. It's quite a remarkable departure from what was the normal practice.
I think they got rid of them because otherwise it would be like turning Treblinka into a Bed 'n Breakfast instead of bulldozing it. They wanted no vestige of the atrocity to remain.

-mickey
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Old July 12th, 2017, 15:48   #22
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Messy oil changes.....just when I thought the world was catching up to the TDI. Evil Beetle was the first zero-mess car I ever had. Most recently my 2015 F-150 had a vertical, cartridge-type filter inside a housing, just like the ALH TDI. And the oil drain plug is plastic, with two O-rings to seal it, in a plastic oil pan. You can pull the plug with your FINGERS by squeezing the locking tabs, yet it's pretty much impossible for it work lose in normal operation. No stripped or seized threads, ever. Just put new O-rings on it once in a while.

And now....back to the Stone Age. Oh well. Can't win 'em all.

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Old July 12th, 2017, 17:00   #23
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I assume by "come by" you mean "drive to Colorado"? Which I'm not against doing, just for the road trip. I'd rather wait until I have the money for a DSG reflash.
-mickey
No, still in tooele at the same place
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Old July 12th, 2017, 17:12   #24
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Quote:
Originally Posted by oilhammer View Post
Intellectual curiosity is a good way to put it, and I am in the same mode with that. So how does SCR equipped VAG engines work? Are the pre and post NOx sensors calculating DEF usage by the reduced value across the substrate in the deNox catalyst? They do not show "real" DEF tank levels, so it cannot calculate it that way.
I have had a few CATA 3.0L engines with failed deNox catalyst faults.
it's complicated. Mostly it's on a feedback loop using the nox sensor(s) but with a few backup modes for various situations. The front and rear lambda sensors come into play along with our good friend the internal models. The system(s) can be configured any number of ways based on various things for each engine model and even different software versions.

We can discuss a bit off the forums if you wish. (email not PM please) I'd be interested to hear about the faults because I'll bet there's a pretty straightforward fix. I would need to know the SW version to be able to take a peek at how things are set up for each of the cars in question.
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Old July 12th, 2017, 20:18   #25
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I had a 13 and now have a 15 Passat and have watched EVERY regen each car has done.

Put 90k miles on the 13 and the regents were much more predictable. About every 250 miles and would last about 20 minutes. The DPF warmup cycle was much more obvious and extreme. Never saw a regen before 150 degrees coolant temp. That car also had EXCELLENT engine braking that I would use every day on off ramps.

The 15 does regens whenever it wants and they last for muck more various times. I’ve seen them start as low as 135 degrees coolant temp. It’s summer and the car is new, but I haven’t noticed the DPF warmup cycle nearly at all. Maybe weather related, maybe not as violent, but it’s more noticeable in winter so I’ll pay more attention then. This car has basically ZERO engine braking. Downshifting basically just results in more noise and on hills that the 13 would slow with downshifting, this car will continue to accelerate and the rpms will just climb. Really wish I could get the old engine braking back, especially since I put paddle shifters in.

Really interested in the polar setup, but would like to talk to someone outside of this thread about it. I have a few questions and requirements that would need to be met that are not obvious from the website.
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Old July 17th, 2017, 15:41   #26
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Quote:
Originally Posted by Locoelectrician View Post
I had a 13 and now have a 15 Passat and have watched EVERY regen each car has done.

Put 90k miles on the 13 and the regents were much more predictable. About every 250 miles and would last about 20 minutes. The DPF warmup cycle was much more obvious and extreme. Never saw a regen before 150 degrees coolant temp. That car also had EXCELLENT engine braking that I would use every day on off ramps.

The 15 does regens whenever it wants and they last for muck more various times. Iíve seen them start as low as 135 degrees coolant temp. Itís summer and the car is new, but I havenít noticed the DPF warmup cycle nearly at all. Maybe weather related, maybe not as violent, but itís more noticeable in winter so Iíll pay more attention then. This car has basically ZERO engine braking. Downshifting basically just results in more noise and on hills that the 13 would slow with downshifting, this car will continue to accelerate and the rpms will just climb. Really wish I could get the old engine braking back, especially since I put paddle shifters in.

Really interested in the polar setup, but would like to talk to someone outside of this thread about it. I have a few questions and requirements that would need to be met that are not obvious from the website.
My 2013 with the fix software now acts like your 15, regen's all over the board- sometimes 2 in one drive- kinda a hot (no pun) mess with the fans running full tote after every shutdown regen or not. Downshifting rev's the crap out of the engine but not as much braking.
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