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Diesel Cayenne and VW emission issue

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Old 01-15-2018, 06:08 PM
  #5161
OmniGLH
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Originally Posted by RS-America View Post
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Eskimo1, thanks for getting pre-fix data! Would complete the picture if someone would also get Pre & Post-fix dyno runs for both a 13/14 and a 15/16 CD.
We have a 2013 CD and got a pre dyno run - Here are our before -at the wheels- numbers run on a Dynojet with data normalized for temperature.
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Max Pwr______203.20___200.97_____202.42
Engine RPM___3.55______3.56______3.54
Max Trq_______354.82___356.82_____352.35
Engine RPM___2.46______2.44_______2.42
.
Still not convinced to get the 'fix' - Would like to see numbers after the 'fix' - We do endurance off-road rally & Overlanding, can not afford to give up performance. One run last summer started at 3800' climbed to 8000' then descended to 4000' in less than one mile.
.
Another potential issue for us is cold weather starts as in the -36F it got to in Yellowknife. Has anyone had the fix in the north, how has it started in sub-zero temps?
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We've had a few weeks of very cold weather in Chicago - below zero for overnight lows, highs in the single digits. Sub-zero starts haven't been a problem.

One thing I *did* notice - seems the cold *really* impacts fuel mileage. I bought my CD used a year ago, and it was a pretty mild winter last year - but I do not recall seeing a huge hit to mileage.

I seem to average 25 when it's super cold - I'm usually over 30. We had a warm week last week and mileage returned - back to low 30s. Not sure if that's a result of the "fix" or if that's normal for these though.
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Old 01-15-2018, 10:10 PM
  #5162
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Originally Posted by OmniGLH View Post
We've had a few weeks of very cold weather in Chicago - below zero for overnight lows, highs in the single digits. Sub-zero starts haven't been a problem.

One thing I *did* notice - seems the cold *really* impacts fuel mileage. I bought my CD used a year ago, and it was a pretty mild winter last year - but I do not recall seeing a huge hit to mileage.

I seem to average 25 when it's super cold - I'm usually over 30. We had a warm week last week and mileage returned - back to low 30s. Not sure if that's a result of the "fix" or if that's normal for these though.

I have not done the fix and I am also seeing lower mileage in the cold winter we have had this year. I guess that is to be expected in a diesel with no spark plug.
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Old 01-16-2018, 11:36 AM
  #5163
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Winter diesel has less BTU's per gallon, so that will impact things too.. It's similar to the hit you take with winter gasoline.
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Old 01-16-2018, 01:14 PM
  #5164
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Originally Posted by Eskimo1 View Post
Winter diesel has less BTU's per gallon, so that will impact things too.. It's similar to the hit you take with winter gasoline.
This is the cause, primarily. Anti-gel stuff reduces the amount of actual fuel in a gallon of stuff that you pump into your tank (resulting in the aforementioned less BTUs). I've found about 1-2 mpg in my Cummins diesel. Not sure, exactly, the impact to the CD yet, since up until this year, it was her DD. Now that I have one, too, I'll be able to check it closer.

Cold air should, in theory, increase power, since the air is denser. That's why we get intercooled turbos. I don't know if there's an optimal temp for diesel engines, though, so as far as I know, there could be a "too cold", too.
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Old 01-16-2018, 01:22 PM
  #5165
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Yeah usually 1-2 mpg loss over the winter, I'd expect.

But 5+?

If I had to make an assumption it would be extra regen's because of the super cold air and the cat not working as well?
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Old 01-16-2018, 11:53 PM
  #5166
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Originally Posted by skiahh View Post
This is the cause, primarily. Anti-gel stuff reduces the amount of actual fuel in a gallon of stuff that you pump into your tank (resulting in the aforementioned less BTUs). I've found about 1-2 mpg in my Cummins diesel. Not sure, exactly, the impact to the CD yet, since up until this year, it was her DD. Now that I have one, too, I'll be able to check it closer.

Cold air should, in theory, increase power, since the air is denser. That's why we get intercooled turbos. I don't know if there's an optimal temp for diesel engines, though, so as far as I know, there could be a "too cold", too.
My experience during very cold weather running (talking low single digits to 0), has been at least 4-5 mpg less than summer or spring operation. I do notice more power when cold. Seems the colder, denser air helps.
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Old Yesterday, 01:30 PM
  #5167
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Originally Posted by PJ Cayenne View Post
My experience during very cold weather running (talking low single digits to 0), has been at least 4-5 mpg less than summer or spring operation. I do notice more power when cold. Seems the colder, denser air helps.
Even pre-fix?

If so then... well... ok then.

Last year here in Chicago, the winter was exceptionally mild, and that was my first winter with the CD, so I may not have a good "baseline" for super cold weather.
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Old Yesterday, 04:28 PM
  #5168
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Originally Posted by PJ Cayenne View Post
My experience during very cold weather running (talking low single digits to 0), has been at least 4-5 mpg less than summer or spring operation. I do notice more power when cold. Seems the colder, denser air helps.
Originally Posted by OmniGLH View Post
Even pre-fix?

If so then... well... ok then.

Last year here in Chicago, the winter was exceptionally mild, and that was my first winter with the CD, so I may not have a good "baseline" for super cold weather.
You know, now that I think about it, in the truck, any time it's really cold, I put on a radiator cover to keep the engine temps up.

If I don't, the engine struggles to maintain operating temp and that may well kill mileage. I've not run extended times like that, although last year during our trip to CO, when it was -10ish driving through WY, the engine was struggling to hold it's normal temps. MPGs were down, but I thought it was because of the bike rack on the back and fully loaded vehicle. Even with warmer temps on the return trip, mileage was down. They were close, so I didn't think much of it, but maybe they were worse on the really cold legs.
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Old Today, 12:11 PM
  #5169
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I was really impressed when I saw the radiator shutters, presumably it's for this very reason.. Speed warmup and keep Temps where the engineers want them. (helps mpg too)
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