MPG improvements

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
I will preface this by saying there are a lot of variables in this analysis and not a lot of miles to smooth out fluctuations. That said...

In my recently acquired 2000 Golf 5 speed, I've noticed the following over the last 3 tanks of diesel that I've filled up. Prior to that, I really wasn't watching mileage.

From earliest to most recent:
- 36.4 MPG. Nearly all city driving. Minnesota winter. Ambient air temperature starts

- 38.5 MPG. Nearly all city driving. Minnesota winter. Frost heater newly installed for entire tank of fuel.

- 42.6 MPG. Nearly all city driving. Minnesota winter. Right foot mod.

I've just replaced my MAF and am expecting a slight bump for this next tank. The previous owner was running a K&N filter, so I suspect a fouled MAF might be robbing a little efficiency. I will post how it turns out.

For full-disclosure, I do not fully top off until I see diesel, so I can't say for sure I have exactly the same amount of fuel in the tank for each trip. Regardless, interesting numbers and certainly trending in the right direction.
 

Padrino

Veteran Member
Joined
Jun 16, 2009
Location
Western US
TDI
2002 / Golf 1.9 TDI 5-speed
I will preface this by saying there are a lot of variables in this analysis and not a lot of miles to smooth out fluctuations. That said...

In my recently acquired 2000 Golf 5 speed, I've noticed the following over the last 3 tanks of diesel that I've filled up. Prior to that, I really wasn't watching mileage.

From earliest to most recent:
- 36.4 MPG. Nearly all city driving. Minnesota winter. Ambient air temperature starts

- 38.5 MPG. Nearly all city driving. Minnesota winter. Frost heater newly installed for entire tank of fuel.

- 42.6 MPG. Nearly all city driving. Minnesota winter. Right foot mod.

I've just replaced my MAF and am expecting a slight bump for this next tank. The previous owner was running a K&N filter, so I suspect a fouled MAF might be robbing a little efficiency. I will post how it turns out.

For full-disclosure, I do not fully top off until I see diesel, so I can't say for sure I have exactly the same amount of fuel in the tank for each trip. Regardless, interesting numbers and certainly trending in the right direction.
As many will confirm, this is the BEST mod you can make to your car. It doesn't cost anything but the return is fantastic.
Well done on the MAF, this will help your car a lot.
Well done, keep us posted.
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
I will preface this by saying there are a lot of variables in this analysis and not a lot of miles to smooth out fluctuations. That said...

In my recently acquired 2000 Golf 5 speed, I've noticed the following over the last 3 tanks of diesel that I've filled up. Prior to that, I really wasn't watching mileage.

From earliest to most recent:
- 36.4 MPG. Nearly all city driving. Minnesota winter. Ambient air temperature starts

- 38.5 MPG. Nearly all city driving. Minnesota winter. Frost heater newly installed for entire tank of fuel.

- 42.6 MPG. Nearly all city driving. Minnesota winter. Right foot mod.

I've just replaced my MAF and am expecting a slight bump for this next tank. The previous owner was running a K&N filter, so I suspect a fouled MAF might be robbing a little efficiency. I will post how it turns out.

For full-disclosure, I do not fully top off until I see diesel, so I can't say for sure I have exactly the same amount of fuel in the tank for each trip. Regardless, interesting numbers and certainly trending in the right direction.



Yes, certainly heading in the right direction. how is the health of your thermostat?
 

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
Good question about the thermostat. I forgot to mention I put in a new one at about the same time as the Frostheater install.

It hadn't been getting up to normal operating temperature. Once I installed the new one, problem solved. Pegged straight up at 190 once warmed up.
 

psd1

Veteran Member
Joined
Aug 4, 2011
Location
OR
TDI
2006 Jetta 2013 Passat SE 6Man
Ventectomy & brim your tank, then you'll really know how many mpg's your seasonaly gaining or loosing. Numbers look good so far.
I agree, without seeing fuel at the brim your numbers are only close. Good job so far on the increases!

PS, start a Fuelly acct, it's a great way to watch your MPG and we can too!
 
Last edited:

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
Will consider ventectomy. Not sure how die-hard I want to be about mileage :)

I've got a fuelly account. How do I get it to post stats in my signature?
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
Click on 'user CP' (upper/left of forum).
Click on 'edit signature'.
Paste in the BBCode image link for your signature & the fuelly URL ... something like this:

{URL= "http://www.fuelly.com/driver/USERNAME/CARNAME" }{IMG} http://www.fuelly.com/sig-uk/SIGNATUREID.png {/IMG}{/URL}

Where { and } are the square brackets, and the username, carname and signature ID are identifiers from fuelly.

You will need to look at the fuelly instructions to find out what they should be.
http://www.fuelly.com/faq/23/Fuelly-forum-signature-badge
 
Last edited:

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
Alright! Just filled up after a 700 mile city tank in my now vented Golf. From looking at fuel, to looking at fuel, just over 45 mpg on this tank. Things keep going in the right direction!

Since last post, I have inflated my 17" tires to the 50psi stated as max pressure. They were at 30-35ish. I also cleaned out my intake manifold which had about 60% blockage. It has also warmed up quite a bit since some of those earlier tanks and I'm getting a little better at timing lights.
 

psd1

Veteran Member
Joined
Aug 4, 2011
Location
OR
TDI
2006 Jetta 2013 Passat SE 6Man
Alright! Just filled up after a 700 mile city tank in my now vented Golf. From looking at fuel, to looking at fuel, just over 45 mpg on this tank. Things keep going in the right direction!
Since last post, I have inflated my 17" tires to the 50psi stated as max pressure. They were at 30-35ish. I also cleaned out my intake manifold which had about 60% blockage. It has also warmed up quite a bit since some of those earlier tanks and I'm getting a little better at timing lights.
Good work, I see the mileage bug has gotten to you and you decided to vent! ;)
It becomes somewhat of an addiction, I used to hate going to the pump, now I am like...dang, I think this is going to be a good tank...I need to fill up and check it out!:eek:
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
It will really come up when the winterized diesel is gone for the season. 17's don't help things and I imagine the ride is punishing with them aired up to 50psi.
 

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
I'm curious to the specific impact winter diesel has. We will see in a little bit here...

Yeah, the 17s are what was on the car when I bought it. It's not really punishing, just certainly not plush.
 

Hansgruber

Well-known member
Joined
Mar 23, 2012
Location
New Jersey, US
TDI
2006 TDI
I'm curious to the specific impact winter diesel has. We will see in a little bit here...

Yeah, the 17s are what was on the car when I bought it. It's not really punishing, just certainly not plush.
I think the colder temps have a larger impact than winter fuel. While winter diesel may have a lower BTU; cold fluids and moving parts are less efficient.
 

smck

Veteran Member
Joined
Mar 27, 2008
Location
south east indiana
TDI
2000 golf man, 2003 golf man
I'm curious to the specific impact winter diesel has. We will see in a little bit here...
The energy content is a bit less depending on the blend. But the block heater will help you quite a bit. You may want to find someone with a VAGCOM if you don't have one and check your injection timing and IQ as well. Just did the Hammer Mod on mine and seems to be making quite a difference both in power and economy.
 

alloutdoorsboy

Veteran Member
Joined
Dec 30, 2006
Location
Va
TDI
2000 jetta
Whilst reading about aero mods I saw that air temp of 33 will result in 10% loss of MPG compared to 90 due to denser air. Probably more significant than lower cetane rating of winter fuel...... Aero moding is the way to go....
 

psd1

Veteran Member
Joined
Aug 4, 2011
Location
OR
TDI
2006 Jetta 2013 Passat SE 6Man
Whilst reading about aero mods I saw that air temp of 33 will result in 10% loss of MPG compared to 90 due to denser air. Probably more significant than lower cetane rating of winter fuel...... Aero moding is the way to go....
How much energy does winterized fuel give up...on top of the cold fluids/oils, colder temps and increased electrical demands due to heater, electric seats, rear defroster etc??

Dont forget a 90 temp drives most to use the A/C...decreasing MPG as well.
 

Cogen Man

Veteran Member
Joined
Jun 4, 2011
Location
Kingston, Ontario, Canada
TDI
2011 Golf TDI DSG.
How much energy does winterized fuel give up...on top of the cold fluids/oils, colder temps and increased electrical demands due to heater, electric seats, rear defroster etc??

Dont forget a 90 temp drives most to use the A/C...decreasing MPG as well.
The BTU content of No. 2-D diesel fuel is generally higher than that of No.1-D diesel fuel. The BTU content of No. 2-D diesel fuel is typically about 130,000 BTU/Gal. The energy content of Diesel Fuel No. 1 is about 95% that of Diesel Fuel No. 2 and will provide a correspondingly lower fuel economy. Typical No. 1 BTU yield is about 120,000 BTU/Gal. Diesel Fuel No. 1 is also lower in viscosity and provides less lubrication for the fuel pump. Average Cetane for No. 2 diesel is about 40, No. 1 diesel will be higher than 40.

Did a copy and paste from a diesel forum. Not sure of the validity of it.
 

Padrino

Veteran Member
Joined
Jun 16, 2009
Location
Western US
TDI
2002 / Golf 1.9 TDI 5-speed
The BTU content of No. 2-D diesel fuel is generally higher than that of No.1-D diesel fuel. The BTU content of No. 2-D diesel fuel is typically about 130,000 BTU/Gal. The energy content of Diesel Fuel No. 1 is about 95% that of Diesel Fuel No. 2 and will provide a correspondingly lower fueleconomy. Typical No. 1 BTU yield is about 120,000 BTU/Gal. Diesel Fuel No. 1 is also lower in viscosity and provides less lubrication for the fuel pump. Average Cetane for No. 2 diesel is about 40, No. 1 diesel will be higher than 40.

Did a copy and paste from a diesel forum. Not sure of the validity of it.
Oh....I miss the minimum cetane number 51 Diesel in Europe :D
 

Padrino

Veteran Member
Joined
Jun 16, 2009
Location
Western US
TDI
2002 / Golf 1.9 TDI 5-speed
Do you also miss paying 1.50 Euro per liter?:eek:
This is one part I don't miss at all :) However with $4.39 a gallon here (3.8 lt) we are not far away to be honest.... I just filled up here in San Francisco on my way back home. I am grateful that my Golf still returning 50+ MPG :D
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
...$4.39 a gallon here (3.8 lt) we are not far away to be honest.... ...
Well, within a factor of two or so! I think it is more like $8.50 or $9 / usGallon at the moment (£ 1.44 / litre = $2.30/litre = $8.70/usGal)
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
Alright! Just filled up after a 700 mile city tank in my now vented Golf. From looking at fuel, to looking at fuel, just over 45 mpg on this tank. Things keep going in the right direction!

Since last post, I have inflated my 17" tires to the 50psi stated as max pressure. They were at 30-35ish. I also cleaned out my intake manifold which had about 60% blockage. It has also warmed up quite a bit since some of those earlier tanks and I'm getting a little better at timing lights.



Did you end up draining your lower intercooler from any accumulated oil? That would be a great idea to do if you haven't done that yet-run away TDI's can make for a very BAD day! :D Also, if you have VagCom, and don't have a tune, consider advancing your timing a few degrees BTDC and trying that out. Another thing that can help fuel mileage is lowering the amount of injected fuel through the IQ adjustment. Raising the IQ number results in lowering the amount of fuel injected.
 

wncre8r

Well-known member
Joined
Mar 4, 2011
Location
M
TDI
2
New head installed and I don't know what size injectors were in it. IQ was 2.8 MPG was bad took the IQ to 5.8-6.0. Temp was 90.4C. Still runs the same but am hoping the Mpgs increase.
 

racerjim

Active member
Joined
Apr 22, 2012
Location
Diamond Bar, CA
TDI
(2) 1996 passat TDI's
So when you raise the IQ you actually decrease the amount of fuel? I had resealed the pump on my son's 96' Passat and set the IQ to right at 3. What would be an optimum setting to try for better fuel economy? Is there an engine timing number that I should shoot for also?

His car can get up to 50 mpg so very good but we'd like to shoot for higher if possible.

I have another 96' TDI Passat that won't start w/o starting fluid and the IQ is like at 12+. I was advised to lower that down as it may not be letting any fuel in to start? Timing on it is like 3.3 degrees BTDC

Any other mods you have done on your Golf to get 60 mpg?

:)
 

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
Did you end up draining your lower intercooler from any accumulated oil? That would be a great idea to do if you haven't done that yet-run away TDI's can make for a very BAD day! :D Also, if you have VagCom, and don't have a tune, consider advancing your timing a few degrees BTDC and trying that out. Another thing that can help fuel mileage is lowering the amount of injected fuel through the IQ adjustment. Raising the IQ number results in lowering the amount of fuel injected.
I haven't drained the lower inter cooler. I'll check that out. My timing is slightly advanced, so I think I'm in a good spit there. I believe I have the stock IQ setting. I'll probably hold pat where it's at and see how things go before changing too many variables.
 

Fauvay

Well-known member
Joined
Oct 12, 2011
Location
Minneapolis
TDI
2000 Golf
Looking good Fauvay. You'll break 50 mpg before you know it. :D
Hard to beat that 66.2 mpg of smck's.
Ha! Thanks! I'm sure I could easily get 50 on more open road driving. We'll see how the next few tanks go. Warmer weather and summer diesel should both help. Maybe a little better with the rut foot too, who knows...
 

josh8loop

Veteran Member
Joined
Sep 15, 2009
Location
Vero Beach, Fl.
TDI
2002 VW Jetta TDI Manual(performed 01M to 5-speed swap) - 183,000 miles and climbing!
So when you raise the IQ you actually decrease the amount of fuel? I had resealed the pump on my son's 96' Passat and set the IQ to right at 3. What would be an optimum setting to try for better fuel economy? Is there an engine timing number that I should shoot for also?

His car can get up to 50 mpg so very good but we'd like to shoot for higher if possible.

I have another 96' TDI Passat that won't start w/o starting fluid and the IQ is like at 12+. I was advised to lower that down as it may not be letting any fuel in to start? Timing on it is like 3.3 degrees BTDC

Any other mods you have done on your Golf to get 60 mpg?

:)


Right, when you RAISE the number in VagCom it LOWERS the fuel quantity injected. Rule of thumb is between 3-5. Now at the same time if you have wild injectors, and a wild IP then all bets are off. The 3-5 rule generally applies to stock or close to stock setups.



Your other 96 that won't start w/o starter fluid-try to take the IQ down to 4 or 5 and see what happens. I bet it will start if everything else is in order. ;) As far as timing, 3.3 BTDC isn't too bad as long as the mechanical is set properly. Theres also a VAGCom setting for start quantity, but that's a whole other bag O worms!
 
Last edited:
Top