Fuel economy - what am I doing wrong?

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Got the fuel filter replaced today, and filled up immediately afterward. Computer said 26.3; real fuel economy was 24.5. It's probably my imagination, but the car seems faster than it was, and I could swear that the instantaneous fuel economy numbers shown on the computer are higher than they were. We'll find out in a few weeks when I next fill up, but I may be able to notice a different in tomorrow's commute. We'll see.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Based on what I see in the computer so far, I expect this tank's fuel economy to be no different than the previous 2 tanks: 24.5 mpg.

So, it appears that my car's problem is not the fuel filter.

At this point I'm not sure what else to look at.
 

kjclow

Top Post Dawg
Joined
Apr 26, 2003
Location
Charlotte, NC
TDI
2010 JSW TDI silver and black. 2017 Ram Ecodiesel dark red with brown and beige interior.
Find someone to check your DPF for soot and ash load. Sounds like your car is using too much fuel in regens. Do you ever notice a rough idle at slightly higher RPM when sitting at a light? Or having the fans run at higher speed after shutting down? Also the burning rubber/rotten egg smell from under the hood. All of these are indications that your cars is doing a regen. Unless all of your miles are highway, you should have noticed at least one of these.

I have the VCDS but no working windows laptop, so can't really help you from Charlotte.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Find someone to check your DPF for soot and ash load. Sounds like your car is using too much fuel in regens. Do you ever notice a rough idle at slightly higher RPM when sitting at a light? Or having the fans run at higher speed after shutting down? Also the burning rubber/rotten egg smell from under the hood. All of these are indications that your cars is doing a regen. Unless all of your miles are highway, you should have noticed at least one of these.
I don't know that I have noticed rough/higher idle at a light, but will start to look for that. I have definitely noticed the high-speed fan running for minutes after shutting down. I wondered what that was; it would make sense that it was regens -- I wondered when my car would be doing that. I think I noticed the smell, and wondered what that was too.

It could also be partly due to my tires, which are Michelin Pilot Sport A/S 3+. I absolutely loved them on my 1.8T, which had the same 225/45-17 size, so I put them on here. Maybe that was a mistake, economy-wise, but they sure are fun to drive.

I have the VCDS but no working windows laptop, so can't really help you from Charlotte.
Thanks. I do have a friend around here with one of those, and I'll see about that soon.

---

Edited to add: Maybe it really is just my commute, which is a mere 5.4 miles and 14 minutes.
 
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Lightflyer1

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Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Your commute also kind of points to regen issues as short tripping all the time never lets it complete one. If you are short tripping it pays to take an active role in ensuring that you let them complete when they happen. VCDS or VagDPF will be needed or something similar or paying close attention to accomplish this.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Maybe I shouldn't have bought a TDI. I live near everything I do, and my 5-mile commute is the longest distance I drive in any given week.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Yep, not ideal use for one. Which, ironically, makes me wonder why you'd be complaining of poor fuel mileage, since you hardly drive anywhere anyway. I mean, heck, you could be driving a V10 Excursion and it wouldn't be a huge deal, LOL. :p
 

Lightflyer1

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Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
A long ways back someone here pointed out that tdi's weren't for sale on some small island(s) due to this. It would be difficult to actually drive there enough to accomplish the regens when needed, without taking special actions to let them happen. At 5 miles you should have been considering an all electric car. They shine for that kind of driving. You do seem to have picked the wrong tool for the job though.
 

Mike14VW

Member
Joined
Jun 13, 2019
Location
Wilpo
TDI
2014
A long ways back someone here pointed out that tdi's weren't for sale on some small island(s) due to this. It would be difficult to actually drive there enough to accomplish the regens when needed, without taking special actions to let them happen. At 5 miles you should have been considering an all electric car. They shine for that kind of driving. You do seem to have picked the wrong tool for the job though.
So, I've been hearing this about the tdi's regen cycle and short distances
..... is there any magic number of say non-stop driving miles one should drive daily for this not to be an issue..
I see this is a loaded question because of all the variables. I drive daily 2miles back roads, 13 miles highway (65 mph) and half a mile to the parking garage. Followed by the same routine in reverse back home. Is this trip sufficient for the health of the tdi's?

Sent from my SAMSUNG-SM-G930A using Tapatalk
 

Lightflyer1

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Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
The only requirement is that they complete when needed. About every 200 to 300 miles depending on your driving. Short tripping will happen earlier than long distance highway driving. I use the VAGDPF app to monitor mine and they kick off when the soot level gets to 23.4 grams and shut down around 4 grams IIRC. Sometimes you can notice as the idle will be at 1000 rpms instead of around 800 rpms. Hard to do by just paying attention though. If one is running I just keep driving until it completes. They generally last about 10 minutes total if all is working well. If you never let them complete it will eventually shut down on you and require the dealer to do a forced regen. At some point even that isn't possible and replacement has to be done. The majority of people won't have an issue as it will try again next drive cycle. But if you are always short tripping they will never complete. A longer drive now and then when needed is all that it would require. You just have to be able to tell when one is needed to keep it happy.
 
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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
Yes, so long as it DOES get a chance to run and successfully complete now and then, it should not be a problem. So, shorter trips during the week coupled with a longer drive every weekend should be fine.

Keep in mind though, post fix cars are going to require more regens, in addition to the already fragile and finicky control system made even worse, so don't be surprised that what was working fine before the fix no longer works now. Which is why the tuners and deleters are having so much business now. Ironic since the whole deal was to try and make clean running cars that were dirty run clean, and now they run so poorly that people make them REALLY run dirty. But whatever.
 

kjclow

Top Post Dawg
Joined
Apr 26, 2003
Location
Charlotte, NC
TDI
2010 JSW TDI silver and black. 2017 Ram Ecodiesel dark red with brown and beige interior.
So, I've been hearing this about the tdi's regen cycle and short distances
..... is there any magic number of say non-stop driving miles one should drive daily for this not to be an issue..
I see this is a loaded question because of all the variables. I drive daily 2miles back roads, 13 miles highway (65 mph) and half a mile to the parking garage. Followed by the same routine in reverse back home. Is this trip sufficient for the health of the tdi's?

Sent from my SAMSUNG-SM-G930A using Tapatalk
From my experience, the regens usually start when I pull into the garage or parking space at work. I could have just completed a 400 mile day and it still seems to want to start an active regen just as I'm shutting it down. I know, it's all timing and this would not have been the first one of the day. If I notice it starting at a light or slower traffic, I'll kick the tranny over to manual and keep the rpms higher for a few extra miles.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
From my experience, the regens usually start when I pull into the garage or parking space at work. I could have just completed a 400 mile day and it still seems to want to start an active regen just as I'm shutting it down.
So true. And so annoying. If I catch it I'll let the car idle for a few minutes, unless I can't because of time or location. I keep telling myself that VW designed the system to accommodate these driving and stopping conditions and it should be fine, but it still bugs me.

What bugs me more is if it starts a regen at the end of a longer drive, but then when I get in to drive a short distance it tries again, and again, and again.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
That is why vagdpf is a good idea. At least you can see where it is at in its cycle and if one is coming due. I have an old android phone that is dedicated for just this one thing. Assuming you can find a version of the cars that works for you. The app owner is across the pond and not all US models are supported, but some still work.
 

IndigoBlueWagon

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Aug 16, 2004
Location
South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Yes, but...all it really does is confirm you're in regen. You still have to decide whether to ignore it or keep driving 'till it's done. Irritating. That's one of the reasons why I use my older TDIs for local driving.
 

kjclow

Top Post Dawg
Joined
Apr 26, 2003
Location
Charlotte, NC
TDI
2010 JSW TDI silver and black. 2017 Ram Ecodiesel dark red with brown and beige interior.
I'm sure that my 17 Ram EcoD regens at least as much as our VWs, I've only noticed one regen in 28k miles.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
I have noticed them on VAG products, but in 11k miles I have never known my Sprinter to be doing one. It either must be more transparent, or the type of driving we do (mostly highway, 75+) is just happens in a very passive manner.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
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Aug 16, 2004
Location
South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
I think it's more transparent on Mercedes and BMWs. I rarely notice it in my 335d.
 

jmodge

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Jun 18, 2015
Location
Greenville, MI
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2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Mack refuse trucks had constant issues. They never ran down the highway unless one of us mechanics took them out. On and off the throttle and they never properly regened because they would get shut down. Worst part there is the ecu would derate the engine and the operators generally didn't bring them in until it was too late. Once past a certain point a regen could not be forced without dealer specific software.
Point being, a diesel with DPf's need to stretch there legs on a regular basis. Tough on manufactures also as the government mandated a 5yr warranty. Backhoes were especially troublesome also.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Yes, but...all it really does is confirm you're in regen. You still have to decide whether to ignore it or keep driving 'till it's done. Irritating. That's one of the reasons why I use my older TDIs for local driving.
No it also tells you where it is at at any given moment as far as how close it is to doing a regen. You can easily tell if it has just regen'd or one is looming really soon or is in progress and about how far along it is. Ash buildup. All usefull info.
 

bigb

Veteran Member
Joined
Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
Monitoring is about the only way to know for sure. I always reset my trip odometer when a regen completes so I know about when the next one will come and I will start to monitor when it gets close. City driving I will see regens approx 125 miles apart, highway about twice that.

I have a dedicated phone for Vag-Dpf and torque pro, on trips I run the TP and watch egts, coolant and regens. TP shows percent of DPF load to 100% then regen starts, however it does not show it decrease like VAG-DPF does so you don't know how close it is to finishing, so if I am close to my destination I switch to VAG-DPF so I can see the progress. Keeping the RPMs up, or on the highway I can get it to finish in 11 min. trapped in city traffic it will take 20-25 min.

I really wish there was an app to allow management of the regens, to allow you to delay or advance to fit your driving cycle. If you knew one was coming up and you were 15 min from your destination you could advance start it so it could finish just before you arrive, or if one were about to start just as you arrive you could delay it till your next drive cycle. They do seem to initiate at the worst times.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Guess I'm a bit of a luddite about this stuff. I just want to drive the damn car. I don't like the FE readout, either. I prefer not to think about it until I refill. How I'm doing based on gauge position and trip mileage is enough info for me.
 

bigb

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Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
Guess I'm a bit of a luddite about this stuff. I just want to drive the damn car. I don't like the FE readout, either. I prefer not to think about it until I refill. How I'm doing based on gauge position and trip mileage is enough info for me.
It's a sort of sickness and you are probably better off without it. Been a gear head all my life, can't stop, I want to know all I can about my rides
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
Well if you are actually driving the car enough, you need do nothing. If you choose to be informed, even if it is just to satisfy your own curiosity, then that option also exists.
 
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