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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW MKIV-A4 TDIs (VE and PD)

VW MKIV-A4 TDIs (VE and PD) This is a general discussion about A4/MkIV Jetta (99.5-~2005), Golf(99.5-2006), and New Beetle(98-2006). Both VE and PD engines are covered here.

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Old November 14th, 2003, 12:33   #1
nrvcentr
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Join Date: Nov 2003
Location: Vancouver
Default How to improve mileage

Recently acquired a 1999 Jetta TDI. It gets pretty consistently 800 KM/Tank. Can this be improved?
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Old November 14th, 2003, 13:31   #2
VDubVerruckt
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Join Date: Jul 2003
Location: Scottsdale, Arizona
Fuel Economy: 50.1/43.4/36.4 mpg
Default How to improve mileage

You'll find all your answers and more in the TDI Fuel Economy Forum! [img]/images/graemlins/smile.gif[/img]
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Old November 14th, 2003, 16:51   #3
RichCA
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Join Date: Jan 2003
Location: Ontario
Default How to improve mileage

Vent your tank and you'll get 1000km. My gas light comes on at about 1050km and I do city and highway driving. I'm pretty heavy footed too. I also use powerservice and Sunoco gold diesel. On a stricly highway trip 650km each way and about 100km city driving, I got 1400km on a tank.

Rich
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Old November 16th, 2003, 01:06   #4
Powder Hound
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Join Date: Oct 1999
Location: Conkud, New Hampshiyuh, USA
Fuel Economy: pretty freakin' good.
Default How to improve mileage

The best way to improve mileage is lighten your right foot.

Really, the very best way for any car is to drive more slowly.

If that right foot is fat, can't keep it off the floor, well, sorry.
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Old November 17th, 2003, 09:24   #5
Metalnerd
 
Join Date: Nov 2000
Location: Greensburg, PA, USA
Fuel Economy: 51/45/39
Default How to improve mileage

In 150 K miles on my Passat, the following have showed a significant reduction in MPG.

1) Short Trips. During warm-up, the TDI seems to consume a bit more fuel.

2) Winter Fuel. Expect perhaps 10% MPG reduction with winter fuel.

3) Tire Pressure: Can sneak up (down) on you and seems to pull down the MPG.

The only time I ever registered 39 MPG was on winter fuel and driving to jury duty 1 mile from home every day for a week.

Spirited driving seems to have little effect on my Passat's MPG. Even 100% city cycle driving is not bad if done for long periods of time. Minimizing cold starts is a biggie.
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Old November 17th, 2003, 11:22   #6
gdr703
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Fuel Economy: 65/62/60 mpg US
Default How to improve mileage

[ QUOTE ]
nrvcentr said:
Recently acquired a 1999 Jetta TDI. It gets pretty consistently 800 KM/Tank. Can this be improved?

[/ QUOTE ]

I am also in Vancouver.
I have a Golf, and typcially get 1200 km per fill up of 46 litres.

I use Mohawk/Husky DieselMax fuel,
additives to boost Cetane (Lubetec, Stanadyne) and lubricity (KleenFlo),
and tire pressures are up.
PC Duron 5W40 engine oil
hth
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Old November 17th, 2003, 21:26   #7
TDiMike
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Location: Vancouver, BC, Canada
Fuel Economy: 49/40/35 MPG
Default How to improve mileage

gdr703:

I have a Golf TDI in Vancouver, use Mohawk or Shell diesel, use Stanadyne Performance Formula and PC Duron oil (changed every 10-12K km). I don't vent my tank while filling. My 15" tires are properly inflated and yet I find the gas light comes on between 750-875km depending on how much hwy driving I do (averaged of 26 months of ownership). Given that the Golf tank holds 55L, I figure the gas light comes on around 45-50L. That would mean that you are driving 325-450km more on the same amount of fuel, in same climate, than I.

I don't drive the car 'like it's stolen' so am curious - how do you get 1200km out of each tank? Do you vent a lot at fill up? Do you fill your tires with more air than is recommended? How much Hwy percentage do you do and what does your trip odometer say when your gas light flashes on?

Thanks,
mike
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Old November 18th, 2003, 10:10   #8
gdr703
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Fuel Economy: 65/62/60 mpg US
Default How to improve mileage

[ QUOTE ]
TDiMike said:
gdr703:

I have a Golf TDI in Vancouver, use Mohawk or Shell diesel, use Stanadyne Performance Formula and PC Duron oil (changed every 10-12K km). I don't vent my tank while filling. My 15" tires are properly inflated and yet I find the gas light comes on between 750-875km depending on how much hwy driving I do (averaged of 26 months of ownership). Given that the Golf tank holds 55L, I figure the gas light comes on around 45-50L. That would mean that you are driving 325-450km more on the same amount of fuel, in same climate, than I.

I don't drive the car 'like it's stolen' so am curious - how do you get 1200km out of each tank? Do you vent a lot at fill up? Do you fill your tires with more air than is recommended? How much Hwy percentage do you do and what does your trip odometer say when your gas light flashes on?

Thanks,
mike

[/ QUOTE ]

Mike,
Only happy to share.
When I fill up I set the nozzle on the slowest fill speed and leave it alone to fill until it clicks off. Then i top off with a litre or two till the foam is visible and I run out of patience. So that's topping off as opposed to venting. Clearly I do not vent.
i usually fill up before the fuel light comes on. But on those occasions when the fuel light does come on i might have 1220 or 1260 km on the trip meter. My last tank, the fuel light did come on when I was going to Chiliwack and I filled at 1252 and 47.8, (at C$0.619, so I was a little extra patient)
My tire pressures are at 40-42 psi. Some would say thats not "proper", too high. The pressures stated on the car are the theoretically correct for the tire to bear the weight of the car, not what is "right", or what I feel is right.
I live near HorsehoeBay, I commute early, and is either along the upper levels highway (90-80km/hrlimit), or the marine drive pretty route (60km/hr limit). So i guess i get some steady driving in there. (often hit 115 overunning- wheeeeee - down the cut)
I use 5th gear a lot. I change gears at low rpm and drive the torque.
I use Mohawk DieselMax, Lubetec Cetane booster, Stanadyne performance formula, and Kleen-Flo lubricity.

My guess is the differences between us are two fold. 1) the tire pressures, and 2) the use of 5th gear, low rpm's, drive the torque.
(The additives I think help the use of the low rpm's, as they improve the engines torque output at low rpm, at least that's what I believe I experience.)

hth
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Old November 19th, 2003, 07:17   #9
snoopis
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Location: Arlington, TX, USA
Default How to improve mileage

[ QUOTE ]
gdr703 said:
...When I fill up I set the nozzle on the slowest fill speed and leave it alone to fill until it clicks off...

[/ QUOTE ]

Just a note: The only time I've ever had a pump fail to click off(thus, make a mess) was when I had the pump going slowly. It seems like pumping slowly is good to keep the foam down, but just keep an eye on it.

-Nick
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Old November 19th, 2003, 08:16   #10
TDiMike
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Fuel Economy: 49/40/35 MPG
Default How to improve mileage

gdr703, thanks a bunch for taking the time here. Local experience is so good to hear. You do indeed run you tires at greater pressure, but it sounds to be working out problem free.

Please post up if you see a change in your mileage in winter vs summer as we get more into it. Cheers, Mike.

You are likely shifting much lower than I. I've been told by my dealership to shift at 3000rpm to help reduce carbon-up of the EGR. Apparently most of the dealer's customers who had EGR buildup problems, inevitably shifted at lower RPM when questioned about how the drive the car.

I obvious don't know if this rumour is true, but after doing an EGR cleanout I've been cautiously shifting at 3000-3100.

I don't imagine shifting @ shifting lower rpm's for one tank will change much in my engine, so I'll give it a try to see how much the gas mileage goes up.

Again, thanks for sharing. You do more Hwy driving in your daily commute than I do, so that also helps (except on days when it backs up on the Cut!).
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Old November 19th, 2003, 09:09   #11
gdr703
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Fuel Economy: 65/62/60 mpg US
Default How to improve mileage

I got the car in January 2002, so I have only been through 1 winter. (was that a real winter last year?) I think I can say that in Vancouver we do not get Winter diesel. At least I did not see a significant drop in mpg's in winter, or a significant increase coming out of winter into summer. What I do notice is a drop in mpgs during wet weather, the roads are wet, and puddl-y, can cause mpg's to drop by 5% or 10%. The fuel gauge I think is accurate to +/- 5 litres so its hard to tell sometimes!

As for the coke up of the intake, and dialing out the egr. I haven't done anything with the egr. The car now has 60,000 km on it.
At 40,000km I took a peek into the throat of the egr with my 1million candlepower sooper dooper lamp. Hey is was black in there! It looked like black velevet, but really matt black. The coating was maybe 1mm thick, was very dry and powdery, had a windswept appearance, little channels cut in the surface. I touched it with my finger and there was hardly any resistance, and my finger was coated with a very fine dry black powder, finer and blacker than anything else i've seen.
At 56,000km I took another look. This time the coating was black and shiny, and of no thickness at all. Like it had been smeared with this really black oil. I have no idea why there was such a difference, as the only thing I had changed was the concoction of my additives.
Since then, the car has refused to start twice. On both occasions it was right after I had turned the car round. ie backed out of the garage turned round and backed into the garage, basically ran the engine for 30 seconds, and drove 60 feet. Having loaded, unloaded the trunk, whatever, maybe an hour or so later the car refuses to start.
The culprit was the anti-shudder valve which had not re-opened. Just touched it and it reopened, and the car started again. So obviously that black oily residue inside the egr is having an effect on the anti-shudder valve, causing it to be sticky.
The other point though is that the story behind the blocked intake manifolds is more complex than is often being presented/discussed.
I think I read on this forum about a Vancouverite who had a blocked intake at 50,000km. (?Petrolero? -not sure) That car was driven with some revs and still it blocked up, and at a relatively low km. So go figure. he was using Tempo fuel, and Lubro-Moly additive, if i recall correctly.
hth
cheers,
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