Author Topic: Things I can check to get better fuel mileage (Read 8609 times)

insdtanoodles · « **on:** December 12, 2005, 10:25:08 pm »

Ok so I have a 96 jetta with a 1.9TD and on this tank I will be getting around 500 -550km, thats 10L per 100k :cry: I think I will have the engine out of the car next week and I need some things to check, I am going to try and clean out my intake but thats all I can really think of. There is alot of play in the turbo spool but I can definetly tell that there is still boost in the car but I dont know how much. I dont really have to tools the time the pump, I made a special adapter so I could use my dial indicator to time it but mine only has .085 play, the manual says I need more to time it. I have new snow tires on the car and they are bigger then stock tires, would that make it worse? The front alingment is out but I cant do anything about it untill I replace the front strut mounts. cant think of anything else but this fuel mileage is killing me, I hit 230km at half tank :cry: :cry: :cry:

jtanguay · « **Reply #1 on:** December 13, 2005, 07:26:09 am »

Could possibly be the way you drive it as well. The 1.9TD is a low rpm beast, meaning you should probably shift before hitting 2k rpm. My guess would be possibly injectors, and timing. Does your car burn any oil?

zyewdall · « **Reply #2 on:** December 13, 2005, 09:17:33 am »

Snow tires will definitely affect it. They are generally softer rubber, and bigger tires give more rolling resistance and more inertia to get turning which will hurt you. However, bigger tires also give lower rpms, which cna help you.

If you have an EGT guage, you can try advancing the timing more than factory, which is supposed to increase mileage, but it's a little risky without an EGT. I don't have one, so I haven't done that to mine yet. You can also turn down the fuel screw, but then you get less power too. Are you getting alot of black smoke? If so, that's fuel that wasn't completely burned, and your thermodynamic efficiency is dropping through the floor when it's making smoke.

Use the highest temp thermostat you can get for it. New air filter. Make sure the exhaust isn't plugged. Synthetic oil in the tranny.

That's about all I can think of.

ricosuave · « **Reply #3 on:** December 13, 2005, 03:14:39 pm »

as a fellow 1.9 idi owner....

check the obvious too

- tire pressure (i keep mine at 38 rear, 36 front)
- fuel filter
- air filter
- driving habits
- remove roof rack, excess weight in trunk, etc.
- no air bubbles in fuel lines

injectors/timing may be a problem as well, but try the other stuff first

remember that with winter diesel, you generally get sligthly less kms too

- try using additives if you dont already.
- use quality diesel, dont always get the cheapest, no name crap

i get about 850-900 in the summer, about 50-100 less in the winter. i generally shift around 2000 rpm.

- all the other comments posted before me!

hope it helps.

rico

ps let us know what you did and if it made a difference!

QuickTD · « **Reply #4 on:** December 13, 2005, 06:00:55 pm »

Three most important things to check when fuel economy is poor, timing, timing and timing! On a 1.9TD slightly advanced from stock is best for economy and power, 0.95-1mm.

insdtanoodles · « **Reply #5 on:** December 15, 2005, 09:05:13 am »

Well I dont think my car burns oil, its hard to tell because its also leaks oil so every now and then I have to top it up. AFAIK the car doesnt smoke all the much, I cant really see any smoke when I look at my mirrors and set on the gas pedal but when I start my car it usually leave and nice black mark on the ground so I cant tell if it is burning oil. I usually shift around 2.5k-3k maybe I should tone it down abit but I dont drive all that aggressively in the city. I do drive very short distances, shut the car off. I usually drive to school and its 5km away, then back home, then to the gym which is 3km away and back home again, on a cold morning when everyone is driving slow the engine never does reach its normal operating tempature. Tire pressure I am going to check this weekend, fuel and air filter have about 5k on them, I only have bubbles in my fuel lines when my fuel tank is getting pretty low. I use fleen flow diesel additives and I usually get the cheap stuff but today I went and filled up on good diesel so I will see how that goes. I dont have to tools to time my injection pump or advance it but I have been looking around for someone in the gta that can do it but now luck. Well I got a full tank and I will see where that gets me but this last tank I got 525 with about 2L left in the tank.

jtanguay · « **Reply #6 on:** December 15, 2005, 12:57:05 pm »

thats pretty low kms... I get that much when I drive the living crap out of my car.

Cheesetoast · « **Reply #7 on:** December 18, 2005, 05:08:55 pm »

my 93 td with 270,000km gets about 750 per tank in the summer, 650-700 in the winter now, i drive it pretty soft, but occasionally have some fun. mods are tdi intercooler, fueling turned up, boost at 20psi, k&n panel filter.

i dont' burn a drop of oil, i run amsoil 5-40 europeon car formula synthetic

i should be getting better milage, i'm going to have the pump timing checked soon

check in your airbox, there is some extra pipes in there for quieting the sound etc, take the pipe off the front of the air box, it restricts flow, and take the one out of the top half of the air box too.

if you have bubbles in your fuel line, replace the plastic 1 way valve on the top of the fuel filter in the engine bay, easy to change, and about a $10-$20 part, i had bubbles in mine, this fixed that.

Cheesetoast · « **Reply #8 on:** December 18, 2005, 05:11:34 pm »

my coolant temp stays about 70 on my guage (canadian cluster) is this a low temp thermostat? would it REALLY make a big difference in milage? i figure the lower temp coolant is better for more power.

Quote from: "zyewdall"

Use the highest temp thermostat you can get for it. .

zyewdall · « **Reply #9 on:** December 19, 2005, 08:46:15 am »

Quote from: "Cheesetoast"

my coolant temp stays about 70 on my guage (canadian cluster) is this a low temp thermostat? would it REALLY make a big difference in milage? i figure the lower temp coolant is better for more power.

That's only a 160F. I thought that 180 or 190 was more common. I've seen other posts on here with more direct experience with different temp thermostats than I have. Hopefully someone will chime in.

zyewdall · « **Reply #10 on:** December 19, 2005, 01:32:10 pm »

Hmmm. I would think warmer would be for more power too. My truck has more power when it's nice and warm, compared to when I first start it. But that's comparing a 190F engine to a 30F engine, not a 160F engine. It definitely has more power when it's really cold outside, but I figure that is due to higher charge density from cold air.

Funny thing is that when it's first started cold, it still has decent torque, but the power drops out complete at higher RPM -- like 2,000 rpm. Is this something to do with compression ignition engines? On old gas engines, I'm used to having to rev them more to keep from stalling until they warm up.

Sorry, this thread is sort of going off topic.....

Quote from: "libbybapa"

Quote from: "Cheesetoast"
i figure the lower temp coolant is better for more power.

I don't get that. Please explain. I would think the reverse. I would think that having the engine cooler would cause more heat to trasfer to the engine rather than turning the crank due to the greater temp differential. It also makes your cooling system less efficient at removing heat from the radiator. I would also think that the lower temp would cause the oil to be thicker and not burn off contaminants from the oil properly causing excess wear, yad, yada... Overheating is the worst. Overcooling is next to worst IMO.

Andrew

chrissev · « **Reply #11 on:** December 22, 2005, 02:39:24 pm »

Quote from: "ricosuave"

as a fellow 1.9 idi owner....

check the obvious too

- tire pressure (i keep mine at 38 rear, 36 front)
- fuel filter
- air filter
- driving habits
- remove roof rack, excess weight in trunk, etc.
- no air bubbles in fuel lines

injectors/timing may be a problem as well, but try the other stuff first

remember that with winter diesel, you generally get sligthly less kms too

- try using additives if you dont already.
- use quality diesel, dont always get the cheapest, no name crap

i get about 850-900 in the summer, about 50-100 less in the winter. i generally shift around 2000 rpm.

- all the other comments posted before me!

hope it helps.

rico

ps let us know what you did and if it made a difference!

re tire pressure: 38psi? wow, that is like pretty high. I usually stop at 32, often a bit lower. You must have a real stiff ride with that sort of pressure.

jtanguay · « **Reply #12 on:** December 22, 2005, 02:47:21 pm »

38 psi sounds about right... i put mine at 40 psi. less grip, less friction, more mpg

when its really cold I wont put 40 psi, since when it warms up the tires might blow etc.

toolie · « **Reply #13 on:** December 24, 2005, 11:13:57 am »

Hmmm, some good info here.

I guess I'm doing pretty good with >380,000km on the clock. Since I've only gone through a few tanks of fuel I'll get about 750/tank. That's with winter diesel, 2000-2400rpm shifts(3000 occ.) and snow tires running 35-38psi. Something I'll have to do this spring, althought it wil not affect milage, is spring/struts. :cry:

Oh, btw the coolant temp needle barely moves if it does at all. Kind of woundering if the car would benifit with a winter front cover like the dmax does.

jtanguay · « **Reply #14 on:** December 24, 2005, 12:51:58 pm »

Quote from: "toolie"

Hmmm, some good info here.

I guess I'm doing pretty good with >380,000km on the clock. Since I've only gone through a few tanks of fuel I'll get about 750/tank. That's with winter diesel, 2000-2400rpm shifts(3000 occ.) and snow tires running 35-38psi. Something I'll have to do this spring, althought it wil not affect milage, is spring/struts. :cry:

Oh, btw the coolant temp needle barely moves if it does at all. Kind of woundering if the car would benifit with a winter front cover like the dmax does.

hmmm i would only put a winter cover on temps around -10c the car could possibly overheat if there wasn't enough cold wind and if it was stationary. maybe your temp gauge is broken?