Mileage

[shakakan]

I am currently getting approximately 33 mpg with my 91 Jetta NA. What are some ideas for better mileage? I am sure the timing needs to be adjusted, but what else could account for such a low number? Most of my driving is in town, and I don't drive it hard. The tires are good, alignment is reasonable, brakes are not dragging. The motor is excessively worn, and needs a rebuild, but I didn't think it would account for such low mileage. What are your thoughts?

[vwmike]

I am currently getting approximately 33 mpg with my 91 Jetta NA. What are some ideas for better mileage? I am sure the timing needs to be adjusted, but what else could account for such a low number? Most of my driving is in town, and I don't drive it hard. The tires are good, alignment is reasonable, brakes are not dragging. The motor is excessively worn, and needs a rebuild, but I didn't think it would account for such low mileage. What are your thoughts?

Right off, I would guess that perhaps the fuel is just turned up too high. Is the anti-tamper collar still on the fuel screw?

[shakakan]

No, the collar was removed by me, but the fuel is set where it was from the factory.  My other thought is that the smoke screw has been adjusted.  It is set to where it was when I got the car, but it could have been changed without me knowing.  I might turn the fuel down, and see if my mileage improves.

[VWRacer]

If you have an automatic trans, you mileage is only about 3 or 4 off what auto-TDI's get. If it's a manual, that's too low.

[jtanguay]

for that mpg you might as well get a gasser  :?

[Mark(The Miser)UK]

Maybe your injectors are dribbling...

My Quantum does 36mpg on the mile city run and 50mpg on the interstate at about 70mph allmpgs in US gal equiv.

Stan what do you get in your 'Q'?

[racer_x]

Are you sure your thermostat is good? I've seen bad mileage from a thermostat that's stuck open. Mine dropped from mid 40's (typically 46-47mpg) down to upper 30's when the thermostat went bad.

And low compression or excessive blowby will also sap a lot of power and require a lot more fuel to keep the thing driving.

[dieseltech]

could be the cold weather diesel that is loaded with k1 kerosen.
my milage is in the low 40's to high 30's   i usually add 1 qt of the cheapest oil i can get in the gas station to every take full.
it gets my milage back up to 45-50 and saves my $900 pump rebuild.

also you odometer might be off, do you have different size tires than what belong on the car?

[Dr. Diesel]

what rpm are you turning? perhaps it's not the original tranny, and has a shorter 5th/final drive ratio than stock diesel

[Northboundtrain]

First off, is the car consuming oil?  If yes, then you should do a compression test for sure.  Is it smoking?  Black smoke indicates partially burnt fuel which means the fuel screw could probably be turned down.  White smoke indicates unburnt fuel which could be dribbling injectors or really bad compression.  Bluish smoke is burning engine oil.  Have you changed your air filter recently?  Also I'd check the motor mounts; the rubber in the mounts can deteriorate to the point that the engine rattles escessively and isn't transmitting energy as efficiently to the drivetrain.

If you decide that your compression is good enought to invest a little in this engine, consider having your injectors rebuilt or get new ones  (you should inspect the injector tips when you do a compression test).  coloradobiodiesel.com offers a superior injector rebuild.    

Winter fuel does hurt fuel mileage by 10% - 15%, but 33 mpg is low for this car.  My '91 Jetta does 40 mpg in the winter and 45 mpg in the summer.

[Cheesetoast]

I average 6.32L/100km in my 93 golf td, new injectors, seems a little low to me, think I should look into it?  car barely smokes.

[jtanguay]

my 1.6TD gets about 40 mpg in winter.   Shouldn't an N/A get better fuel economy???  I've heard of N/A's getting somewhere in the range of 75 MPG???

[shakakan]

The motor has excessive blowby.  I will not be rebuilding it till this summer.  It still seems like the mileage is alot lower than it should be.  I think I am going to tinker with the timing and turn the fuel down, see if I can't get it up a little bit.  I might just have to live with it till I rebuild it this summer.

[VWRacer]

Maybe your injectors are dribbling...

My Quantum does 36mpg on the mile city run and 50mpg on the interstate at about 70mph allmpgs in US gal equiv.

Stan what do you get in your 'Q'?

I get mid-40's in combined city-highway driving, so my guess is that it would break down about like yours, Mark.

[Mark(The Miser)UK]

Maybe your injectors are dribbling...

My Quantum does 36mpg on the mile city run and 50mpg on the interstate at about 70mph allmpgs in US gal equiv.

Stan what do you get in your 'Q'?

I get mid-40's in combined city-highway driving, so my guess is that it would break down about like yours, Mark.

Ah Quantum driving; so much better than hopping around in Rabbits. It gives the diesel something to pull rather than having it attached to a paper bag  :twisted:

Stan do you have those roof bars as well? I've had 200kg of scaffolding tubes on mine. (Like to see a Jetta carry that)  :twisted: