Horrible MPG, but car runs excellently? 2012 Jetta Sportwagen

coolusername

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Orange, CA
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2012 Jetta Sportwagen TDI
If they are anything like dealers in the UK. Then without a CEL your unlikely to get anywhere.

You can imagine it. Hundreds of customers walking through the door. Blaming their MPG on exhaust
I'm optimistic, my dealer's been good to me. They spent two weeks last summer hunting down an occasional no-start that ended up being a slightly loose plug connection near the fuel pump, and then they replaced the crank position sensor and somehow got it all covered under the Dieselgate warranty. And I had a nice, covered rental during the time period.
 

coolusername

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2012 Jetta Sportwagen TDI
did you find soot in the tailpipe ?




Is this sooty? I can barely get anything on my tissue paper unless I scrub it round inside the exhaust pipe, but it still doesn't look quite right. I can't tell if it's just dirty from normal use or anything different.
 

Shoveltrev

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2002 new beetle deceased, 2003 jetta . 2002 jetta , 2012 sportwagon
so grey ash is good anything black is not. its really just another symptom. vw service bulletin sayspull the egr filter off of the dpf and check it for sooot. if there is any soot in the egr filter the dpf is compromised . . thats how they are supposed to do it anyway. my stock cjaa regens every 450 or so miles and thats half as much as yours and i do a lot of in town driving. a lot . like 300 out of those 450 miles .just my observations
 

Shoveltrev

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2002 new beetle deceased, 2003 jetta . 2002 jetta , 2012 sportwagon
something else you can check is do a cold soak test of all your temp sensers. egts coolant and iat. after it sits overnight they all should be within 10% of each other .
 

Full Circle

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2001 Golf GL 2DR HB 5spd manual 93 Ford F250 7.3 IDI NA / sold 2009 VW SW / 2010 GOLF / 2014 BMW 323D
The EPA CARB CA clowns are choking the S+!t out of your engine.
 

briandin

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Monroe Twp, NJ
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Jetta Sportwagen 2011
I have a 2011 JSW CJAA which was entering regen mode often, and then through a code. The dealer determined it was a faulty thermostat and replaced under the CPO warranty the car was under at the time. The fuel economy improved substantially after that. Not saying that is the issue. My car has 114K miles and now I am bringing it back one last time (the magic 54,000 miles from the post sale dieselgate emissions remedy tolls in exactly 1,825 miles) due to a fuel leak (pretty sure its an injector seal). Both of these issues have affected fuel economy but each only to the tune of about 3-5 mpg.
 

ZippyNH

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Southern NH
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2015 JETTA TDI SE
Interesting you said "new tires"...
They stock size? Rims?
Usually new tires is a couple mpg hit...more rubber, more squirm, and slightly bigger diameter....plus the cheapest or ones that give you super long life can be worse. Not saying it's all you problem, mpg issues can be a death by a thousand cuts....
One dragging brake.... roof rack... slightly wider tires.... Heavy aftermarket rims that can sometimes make extra drag (yes big open style rims for cooling)....sometimes plastic air dam parts missing or broken, driving style, fuel....look at the details...lots of little issues equal a big issue
Good luck....
 

coolusername

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Orange, CA
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2012 Jetta Sportwagen TDI
I have a 2011 JSW CJAA which was entering regen mode often, and then through a code. The dealer determined it was a faulty thermostat and replaced under the CPO warranty the car was under at the time. The fuel economy improved substantially after that. Not saying that is the issue. My car has 114K miles and now I am bringing it back one last time (the magic 54,000 miles from the post sale dieselgate emissions remedy tolls in exactly 1,825 miles) due to a fuel leak (pretty sure its an injector seal). Both of these issues have affected fuel economy but each only to the tune of about 3-5 mpg.
So some time has passed, and I did eventually determine the thermostat was an issue. The car was settling in at 180 degrees instead of 190 like it's supposed to. I also installed a CP3 pump, with its associated metering valve from Whitbread Performance. It's too early to say, but the lie-o-meter isn't telling me of any improved MPG, so I fear that the new thermostat hasn't solved the problem. Regardless, this week I'm going to do a full tank of highway driving on the new Tstat and CP3 and will update this post once again.
 

coolusername

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2012 Jetta Sportwagen TDI
Interesting you said "new tires"...
They stock size? Rims?
Usually new tires is a couple mpg hit...more rubber, more squirm, and slightly bigger diameter....plus the cheapest or ones that give you super long life can be worse. Not saying it's all you problem, mpg issues can be a death by a thousand cuts....
One dragging brake.... roof rack... slightly wider tires.... Heavy aftermarket rims that can sometimes make extra drag (yes big open style rims for cooling)....sometimes plastic air dam parts missing or broken, driving style, fuel....look at the details...lots of little issues equal a big issue
Good luck....
Tires are the stock size, so are the rims. They're like ordinary econo tires, I think they're the Yokohama Avid Ascend GTs? Not super sticky, that's for sure. I don't have a roof rack, and the under car aero is pretty decent. I have an Evolution Imports skid plate, so the underside of the front of the car is completely flat. Fuel is standard Diesel No. 2. Sometimes I use R99, but not when I'm trying to go for maximum fuel efficiency as I am now.
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
No, no change in mileage since the timing correction. How can I test for a leaky injector using VCDS?
What does the polor injector numbers look like? Are they close or way spread out?
So some time has passed, and I did eventually determine the thermostat was an issue. The car was settling in at 180 degrees instead of 190 like it's supposed to.
I really looked into the temp. thing too as my temps sit at 180 also.
The limited info I could find says o.e. thermo. is at 188". My mpg is pencil and papered @ epa mileage numbers though so I've not proceeded to change the thermo yet.
 

coolusername

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2012 Jetta Sportwagen TDI
What does the polor injector numbers look like? Are they close or way spread out?

I really looked into the temp. thing too as my temps sit at 180 also.
The limited info I could find says o.e. thermo. is at 188". My mpg is pencil and papered @ epa mileage numbers though so I've not proceeded to change the thermo yet.
Here's a picture of my injectors on the Polar when puttering around town / idling. I think this variation is normal, right? On the highway I think the highest number I've seen is ~0.40 on injector #3, though I have to pay more attention. Also, even with the new thermostat, which should've theoretically fixed my passive regeneration problems, my DPF continues to regenerate every 140 - 150 miles or so with intense city driving.

 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
From the little I understand about this, the closer the numbers are to each other, the better. As long as the numbers balances out. #3 is the furthest variation.
 

coolusername

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2012 Jetta Sportwagen TDI
From the little I understand about this, the closer the numbers are to each other, the better. As long as the numbers balances out. #3 is the furthest variation.
Number 3 is consistently the furthest variation, in all sorts of driving conditions. It's just a question of whether this variation is within spec or not.
 

TDIMeister

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Canada
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The way I'd hypothetically do it, is I may or may not know someone that can pass me my smog regardless. So I'd just delete and do that. Worst case scenario I'd probably do what you're suggesting, parts in and out every two years. First I'm going to try the dealer, one last time before my emissions warranty runs out.
DPF and injectors are should be at the top of the VW tech's look-at list. You reported more frequent regens than you think is normal. That's the first clue I get.

Nevertheless, even when all the vehicle-related factors are stripped out, driving conditions and habits can make an immense difference. Lots of city driving, continuous AC use, (do you have a cargo box on it?), overwide and sticky rubber, can all be potential factors. Sticking brakes also - after a typical drive, quickly get out of the car and go around and feel the temperature of all the wheels.
 

coolusername

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2012 Jetta Sportwagen TDI
DPF and injectors are should be at the top of the VW tech's look-at list. You reported more frequent regens than you think is normal. That's the first clue I get.

Nevertheless, even when all the vehicle-related factors are stripped out, driving conditions and habits can make an immense difference. Lots of city driving, continuous AC use, (do you have a cargo box on it?), overwide and sticky rubber, can all be potential factors. Sticking brakes also - after a typical drive, quickly get out of the car and go around and feel the temperature of all the wheels.
The dealer didn't find anything regarding my MPG issues, and they said my MPG was within an acceptable range. As for the other stuff, I don't have a cargo box, my tires are normal size and not sticky, and I checked the brake temperature thing at the suggestion of a commenter on another forum: they're fine, the wheels don't get hot. As for driving habits, that's why in my initial post I mentioned my MPG with all highway driving, which was 31. All city driving I get somewhere around 22 - 23. Regarding the injectors, what do you think of the PolarFIS readout I posted? Do you have suggestions of things I can check with VCDS?

Honestly at this point I'm thinking the DPF is the problem, but at the same time I want to fix everything else wrong with this car mechanically.
 

CleverUserName

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2014 OZ Cruze CTD & 2010 JSW 6MT & 2017 GMC Canyon CCLB ATX 2.8 Duramax
I think it’s time for a compression check
 

coolusername

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2012 Jetta Sportwagen TDI
I think it’s time for a compression check
Where'd you get that idea from? Nowhere on this forum or any forum have I read of compression issues causing low fuel economy with no other symptoms. The engine runs super smoothly, pulls fine, zero codes. Wouldn't I have other issues appearing simultaneously if I had low compression?
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
Number 3 is consistently the furthest variation, in all sorts of driving conditions. It's just a question of whether this variation is within spec or not.
I don't think 16 is out of range.(?) If I'm off base then someone please speak up.

With the dieselgate tune my numbers where closer and balanced(?) My Kerma are spread now, much like yours, now with Kerma. Good, bad or indifferent??

My temp quickly hits 180 in all ambient temps. Its bugged me but doesn't really seem an issue. My MPG is right on the epa #s though.

Did you mention active regen time & frequency?

Not 100% sure what dur. KW is telling me but some knowledgeable guru input would be appreciated. It could help us all and specifically may shed light for op's diag.

dieselgate @ 76282



Dieselgate tune @ 76424



Kerma tune @ 77268 W/ CPO new DPF etc...


Kerma @ 77412



Kerma tune @ 77918



Not sure what this even indicates but some knowledgeable guru input could help us all and specifically shed light for op's diag.
 

coolusername

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2012 Jetta Sportwagen TDI
I don't think 16 is out of range.(?) If I'm off base then someone please speak up.

With the dieselgate tune my numbers where closer and balanced(?) My Kerma are spread now, much like yours, now with Kerma. Good, bad or indifferent??

My temp quickly hits 180 in all ambient temps. Its bugged me but doesn't really seem an issue. My MPG is right on the epa #s though.

Did you mention active regen time & frequency?

Not 100% sure what dur. KW is telling me but some knowledgeable guru input would be appreciated. It could help us all and specifically may shed light for op's diag.

dieselgate @ 76282



Dieselgate tune @ 76424



Kerma tune @ 77268 W/ CPO new DPF etc...


Kerma @ 77412



Kerma tune @ 77918



Not sure what this even indicates but some knowledgeable guru input could help us all and specifically shed light for op's diag.
My DPF regenerates every 150 - 200 miles, and the regen lasts for about 10 - 15 minutes or so.
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
My DPF regenerates every 150 - 200 miles, and the regen lasts for about 10 - 15 minutes or so.
From what I've seen that is both minimal miles between your active regens and regen length. What is your freeway speed, distance traveled and max. temp. on each active regen?

I forget the actual ash load but you may want to find that out.
 

coolusername

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2012 Jetta Sportwagen TDI
From what I've seen that is both minimal miles between your active regens and regen length. What is your freeway speed, distance traveled and max. temp. on each active regen?

I forget the actual ash load but you may want to find that out.
Freeway speed / distance traveled can vary. The regens do seem to take longer if I'm driving slower. Best case scenario I'm going 70 - 75 and my EGTs according to the polar are around 1200 - 1300 ° F. As for the DPF ash load, that's at 90 mL, and that readout has been at 90 mL since I bought the car about 10,000 miles ago. Other folks say that the ash load *should* be 1 mL per 1000 miles, and it seems that my car is loaded beyond that, since I only have 77,000 miles (bought the car with 67,000 miles). Maybe the previous owner used sh‎itty oil and accelerated the DPF's wear?
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
Do you know if the car has had a DPF? Dieselgate tune?
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
Best get the DPF checked asap! It may have fightable warranty issues even with no CEL. Unfortunately a new car owner has to be smarter than the service writer.

Im no expert at the pictures I'll soon post of my related polar numbers, maybe theyll help to compare with. Maybe you can summon up the likes of oil hammer?
 

coolusername

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Best get the DPF checked asap! It may have fightable warranty issues even with no CEL. Unfortunately a new car owner has to be smarter than the service writer.

Im no expert at the pictures I'll soon post of my related polar numbers, maybe theyll help to compare with. Maybe you can summon up the likes of oil hammer?
I guess I forgot to update you guys, but I did. I took it to the dealer about a month ago, paid the whole diagnostic fee. They didn't find any problems. They even checked for soot in the tailpipe. Everything was operating within VW's conveniently broad parameters. From what I can tell my DPF is slowly failing to the point where when it finally throws a light I'll be well out of warranty. My best option is to delete.
 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
The soot is actual measured soot level (kerma)
The !soot is what is VWs "calculated soot level (absolute b.s.)
VW !soot always triggers the active regen @ around 300 miles for aprox 3 or 4 exits (several.miles)
DPF and misc new under recall (CPO) @ 69K
What is your DPF PSI?

 

JELLOWSUBMARINE

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2011 Jetta Sportwagen, 6M, red/tan, navi, pano, 83 5m diesel pickup, 82 p/u trailer,.04 5.5 TDI Passat wagon (gone), 80,81,82 diesel p/u (gone), 80,82 sportruck (gone), 59 passthru bus (long gone), 79&87 westy (gone), 57 baja bug (long gone), 73 914
Right b4 regen.

 

CleverUserName

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Where'd you get that idea from? Nowhere on this forum or any forum have I read of compression issues causing low fuel economy with no other symptoms. The engine runs super smoothly, pulls fine, zero codes. Wouldn't I have other issues appearing simultaneously if I had low compression?
Because low compression can be a cause of poor fuel economy.

The DPF in my 2009 lasted until 130k when it was sold back to VW. It still got 35 MPGs on average when I gave it up.
 
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