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-   -   Fuel economy - what am I doing wrong? (http://forums.tdiclub.com/showthread.php?t=500698)

eagle July 20th, 2019 15:16

Fuel economy - what am I doing wrong?
 
Hi, all.

I'm not new to TDIs -- I owned a 2006 Jetta TDI DSG from 2006 to 2010, and managed 38 mpg over the 60k miles I tracked (out of the vehicle's 65k total miles). Best tank was 56 mpg (real), and on trips I easily got high-40s.

About 2 months ago I bought a 2013 Jetta TDI DSG, and my average economy has been 26.8 mpg, with a max of 30.6 (all highway), and with decreasing fuel economy with every tank. I have tried various things to improve my economy (varying my driving style) but nothing seems to work.

My 1.8T had a lifetime economy of 26.7 mpg over the time I tracked it (109,255 miles out of 160k total miles). Best tank was 35.0 (real), so I do know how to get economy out of a car.

Any ideas on how I can figure out what I'm doing wrong?

Is it hopeless to expect good (TDI-level) fuel economy out of a "fixed" 2013 Jetta TDI w/ DSG?

Thanks.

Mike14VW July 20th, 2019 15:27

Not the only thing you can do but change the fuel filter. I have a 14' non DSG and gained 4 mpg's.

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Mike14VW July 20th, 2019 15:49

Yeah idk, never had it happen b4with changing the filter, the car had sat for a year up to the fix. I had been tracking it since I purchased the car was averaging 43-44 almost every fill up. Changed the filter after half a dozen fill ups and has stayed at 47-48 every fill up.

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Mike14VW July 20th, 2019 15:50

Maybe just a fluke but I did nothing else differently.

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eagle July 21st, 2019 05:27

Last week I had it at the local shop for an oil change, and had thought of also replacing the fuel filter. I probably should have done it. I did the oil change because I don't know what type of oil the used car lot put in it, and I figure that an oil change is cheap insurance to know that it's the right oil.

Anyway, you can see all of my vehicles Fuelly:
- 2013 TDI: http://www.fuelly.com/car/volkswagen...nixdude/925014
- 2006 TDI: http://www.fuelly.com/car/volkswagen...nixdude/137846
- 2003 1.8T: http://www.fuelly.com/car/volkswagen...nixdude/124470

My car was a VW buyback and it sat for 18 months according to Carfax. Maybe I should just have the filter changed -- no telling whether VW did it, and if they didn't it's probably gunked up.

Mike14VW July 21st, 2019 08:38

Screenshot of my fuel log is attached. In the first 6 fill ups the only fill up that dropped below 40 was fuel I got at sheets. Do what you want, I was amazed that I gained that much from changing the fuel filter. It is a 6 speed and I do drive it to get the max mpg I can. My driving style has not changed all that much since the filter was changed. I used to have an 84 rabbit and I changed the fuel filter every year or two (was like $8 for the canister and easy to do). I tracked the mileage and never gained any mpg. This car I took to the VW dealer and had it changed because of all the electronics, still looks easy just did not want to mess anything up, if its possible. https://uploads.tapatalk-cdn.com/201...8b91b38b07.jpg

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Mike14VW July 21st, 2019 10:05

Quote:

Originally Posted by 35 Yr Dsl Veteran (Post 5523461)
You get much better MPG in HOT weather vs. COLD weather. This could be the answer.

I understand that but middle of may almost into June is when I gained 4 mpg, like switch of a lite bulb....at this time of year, where I'm from.... we should already be out of the winter grade fuel and into warmer temps.... maybe an increase has nothing to do with fuel filter but that would have been the only thing that changed.

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eagle July 22nd, 2019 07:54

Yeah, I think I'll get the fuel filter changed. Can't hurt -- other than my wallet.

Current tank is showing 22.7 mpg on the computer which has proven to always be 10% high. I can't be that hard on it.

I'm the third owner of the car, and the second since VW had. The owner before me had it for two months, and I wonder if it was for fuel economy or hill hold or delayed throttle response... maybe a combination of all of those.

Thanks.

Lightflyer1 July 22nd, 2019 11:47

Something is wrong with your car. When is your timing belt due? Time wise it should be changed soon anyway. I would consider finding a trusted mechanic from our list (a known good one) and having the TB changed properly, with all the required parts and set as well as a full service of everything. 20 mpg is just totally unreasonable for a properly running car. I would have requested a full service when I was buying it, personally, and have advocated for this here many times. These cars have sat for long periods sometimes and could really benefit from a good once over redo. Are your regens happening as needed? What is the soot and/or ash load of the dpf filter?

eagle July 22nd, 2019 16:01

Quote:

Originally Posted by Lightflyer1 (Post 5523724)
Something is wrong with your car. When is your timing belt due? Time wise it should be changed soon anyway. I would consider finding a trusted mechanic from our list (a known good one) and having the TB changed properly, with all the required parts and set as well as a full service of everything. 20 mpg is just totally unreasonable for a properly running car. I would have requested a full service when I was buying it, personally, and have advocated for this here many times. These cars have sat for long periods sometimes and could really benefit from a good once over redo. Are your regens happening as needed? What is the soot and/or ash load of the dpf filter?

Sorry, I don't know what regens are, and I don't know what a dpf filter is.

They changed the oil but as far as I know that's all they did. I do have a good mechanic - a company run by some local enthusiasts, and they are very fair to customers. Great place.

I'll remember your "full service" tip for the next time I buy a vehicle.

Not sure about the timing belt - I'll check that.

Lightflyer1 July 28th, 2019 18:44

You really owe it to yourself to read up here a lot and get familiar with these terms and others. These aren't really cars that tolerate not being taken care of properly or unaware owners (the newer emissions models especially). Nothing against you but there are some things you should be aware of such as the dpf filter (filters soot out of the exhaust stream and requires a burn off every so often, happens automatically and requires replacement when it gets filled with ash. One of the extended warranty items covered.) Regens are when the burn off of the dpf filter happens. About 10 minutes at very hot temperatures every 200 to 300 or so miles depending on what kind of driving you do. City driving will have shorter intervals than highway driving will. I can't explain it all here in one post but there is a ton of info here already for you to read and learn. It also helps to know things to explain to your mechanic better what the issue is. Don't wait too long on that timing belt either. If it breaks for any reason the cost to repair the engine will be great. Good luck and hope you can find the issue. If your mechanic can't find an issue you may want to try one of our trusted mechanics who specialize in these tdi's.

eagle July 30th, 2019 16:25

Yeah, it's pretty clear that the 2013 TDI is not the same thing as a 2006 TDI. I'll do some research and reading up. Thanks.

Lightflyer1 July 30th, 2019 18:52

The 2006 wasn't the same as the 2000 to 2003 either. As they get more complicated there is more to learn. My first was a 2006 Jetta. I have owned about 7 since then of differing years and models.


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