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Fuel economy - what am I doing wrong?

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....
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.
Don't most of those types of applications just have a manual regen method? I lamp that comes on telling the operator one is required, and then a switch that starts the process? I know John Deere does. They use two modes: Auto and Parked. In either case, the light will flash and then come on steady during. Which is something I think would/could be useful in passenger cars and light duty trucks.

Technically, the DPF light coming on is supposed to tell you a regen NEEDS to occur, as it has failed X many attempts. However a lamp that comes on telling you when the process has started would be helpful, because then you would KNOW and, if at all possible, you could slightly change your current driving to allow it to complete.

But the way Volkswagen (and I assume MB and the rest?) have it, once the light comes on, you've already failed any passive attempts.
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Yes they do. However, municipal management priorities are not inline with common sense and can be extremely frustrating. Operators of refuse trucks get pushed hard.GPS systems and tracking systems on cart tippers. The videos provided some entertaining moments for us. Philosophy went from PM maintenance to damage repair.
But yes, the warning system is very good thing to have.
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
They ended up with a revolving door on the shop. An open job posting for mechanics. People used to claw at the door to get in there, now they go the other way. Quite sad actually because it was a great job except for about the last two years I was there.
 

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 think most decent professionals would rather maintain than repair. I know I certainly would. Stuff breaks no matter what, but on vehicles that get regular proper PM it is FAR less frequent, and many things can be done proactively if it gets seen regularly.
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
When I started PM’s were performed monthly with oil changes at 150 hours. Even if a vehicle didn’t need oil changed it got looked over and greased. It was rare to have a vehicle break down in the field. Then oil got pushed beyond 350, fuel filters often past 1200, break in oil on roots blowers that should have been changed at 100 was going nearly 2000. Mechanics were bored and disgusted and the ones who weren’t lifers in the defined pension system left. Quite depressing change to a job that was once fun and highly sought after. Once I was vested in the pension I no longer had a desire to work there and simply walked off. Nothing to take pride in.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
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
So, I have decided that I don't care about fuel economy and am now driving more sportingly and more in manual mode. Interestingly, the trip computer shows greater fuel economy now, but I don't believe it -- real computed FE is stillstuck at 25 mpg, and it doesn't seem to matter how I drive. At least now I get to have fun with it.

The question now is: how much fun can I have? But that's a thread for a different forum, and I'll start a new post about that in the appropriate forum.
 

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 if the cooling fan is running when the car is turned off it's doing a regen?
Not exactly. It could also be running the cooling fans just to get the radiator temp down.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Not exactly. It could also be running the cooling fans just to get the radiator temp down.
If I'm correctly understanding what my car is doing, the fan speed during regen is very fast, and the fan speed during radiator cooldown is much slower.
 

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.
On my 10 and 11 TDIs, I don't think I could tell a difference in fan speed. It was more odor of the burning soot that told me that a regen had been taking place.
 

eagle

Veteran Member
Joined
Apr 14, 2004
Location
North Carolina
TDI
2013 Jetta
Gotcha - maybe it's just a difference between my 2003 1.8T and my 2013 TDI: the 2003 1.8T often ran a radiator cool-down mode with a fan speed that is much lower than what I hear the TDI do. I don't often hear the TDI fans run after I shut it off, but when I do, the TDI is much, much louder, with obviously faster fan speed.
 

El Dobro

Top Post Dawg
Joined
Feb 21, 2006
Location
NJ
TDI
2017 Bolt EV, 2015 Spark EV
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.
Mack's solution.
https://electrek.co/2019/05/08/mack-electric-garbage-truck/
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Interesting, a still garbage truck though, maybe the rats chewing on wires will get zapped with a good dose of amperage
 

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
I don't think it will complete. Not enough heat at idle. It'll interrupt. Still, many believe it's a good idea to let the car idle a while if you stop during a regen, to prevent hot oil sitting in the turbo.
 

El Dobro

Top Post Dawg
Joined
Feb 21, 2006
Location
NJ
TDI
2017 Bolt EV, 2015 Spark EV
It may depend on the circumstances. I'd pull into the parking lot at work and the car would be in full regen. I'd just let it run until everything calmed down before I'd shut it off.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
I would think it quits regen but takes some time to cool down just sitting there. The real test is to see if it starts back up again soon after interrupting it like that. Like with VCDS or VagDpf.
 

bigb

Veteran Member
Joined
Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
I have shut down during a regen and restarted right away, the regen continued where it left off. Once I shut down just as it started and went inside for the night. Next day the regen started over as soon as operating temp was reached. I have been able to get my regens down to 12 minutes in town. I keep the rpms between 1,500 and 2,000, if I hit a red light I pop it into neutral and hold the brake and nudge the accelerator with my right foot (I have size 16D feet) to keep it at 1,500. The soot load continues to tick down just as if I were moving. 12 minutes she finishes and a couple more minutes for the EGTs to cool down to normal. All verified with VAG-DPF.
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Does the software allow a forced regen like trucks do, raising the idle and monitoring egt’s and pressure differential?
 

bigb

Veteran Member
Joined
Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
Does the software allow a forced regen like trucks do, raising the idle and monitoring egt’s and pressure differential?
Yes, a standing regen can be initiated by VAG capable diagnostic software. OBDeleven will do it.
 

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
The software in the car does not allow you to initiate a forced regen on demand. If you have the factory tool or VCDS or similar then yes you can do it. Not something you would want to carry around and hook up and do in the parking lot though. It would be easier and faster to just keep driving for 10 minutes or less.
 

Diesl

Veteran Member
Joined
Dec 3, 2012
Location
Chicago
TDI
'78 Golf Diesel (long gone); 2012 Jetta Sportwagen TDI w/ DSG
Regeneration DOES finish at idle!

The question is though will it complete just sitting in a parking lot at idle? I think not.
Regenerations most definitely continue at idle on my 2012 TDI Sportwagen. It's easy to observe if you monitor the exhaust gas temperatures.
 

jmodge

Veteran Member
Joined
Jun 18, 2015
Location
Greenville, MI
TDI
2001 alh Jetta, RC2 5speed daily commuter and 2000 alh Jetta 5spd swap, 2" lift, hitch, stage 3 TDtuning w/502's backroad cruiser
Regenerations most definitely continue at idle on my 2012 TDI Sportwagen. It's easy to observe if you monitor the exhaust gas temperatures.
Probably injects diesel fuel upstream of the dot. Unless you inject def. trucks would do the same, ecu watches egt’s and controls injection
 

Diesl

Veteran Member
Joined
Dec 3, 2012
Location
Chicago
TDI
'78 Golf Diesel (long gone); 2012 Jetta Sportwagen TDI w/ DSG
Probably injects diesel fuel upstream of the dot. Unless you inject def. trucks would do the same, ecu watches egt’s and controls injection
The TDI does late fuel injections in the cylinder; this is all known and has been discussed here.
An advantage of idle regenerations is that the turbo temperature is lower, at least from what I am seeing.
 
Joined
Sep 20, 2019
Location
Salem or
TDI
Mk4 golf tdi bew vnt17
My tdi is experiencing low fuel economy, 32 mpg in the past ive gotten 40mpg with a 2 bar map and vnt17 turbo.
Ive gotten a check engine light with intermittent excess fuel in the exhost and when i looked at my egr it was gunked up so i cleaned it. I was wondering if my problem a dirty intake or bad fuel injectors. Listed below will be my readings.
 
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