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Engine Specific Info and Questions => IDI Engine => Topic started by: shakakan on March 22, 2005, 04:50:51 pm
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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?
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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?
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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.
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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.
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for that mpg you might as well get a gasser :?
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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'?
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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.
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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?
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what rpm are you turning? perhaps it's not the original tranny, and has a shorter 5th/final drive ratio than stock diesel
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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.
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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.
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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???
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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.
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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. :D
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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. :D
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:
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No roof bars on mine. But yes, the 1.6TD does pull the Q-ship nicely.
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No roof bars on mine. But yes, the 1.6TD does pull the Q-ship nicely.
:idea: If it's the estate (er wagon) then the factory fitted roof bars will fit on... The internal double skin is pre drilled for the bolts and the outer skin can be drilled from inside the car. Look out for some on a dead 'Q'.
seal mounting flange with a little roofing mastic which stays plastic. :idea:
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I've been getting between 41.7 and 44.2 US mpg (~5.3-5.6 L/100km) in my 94 Golf during the winter. I drive about 80% highway 20% city.
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Mine's a sedan (we don't say saloon - that means "pub" here... ;)), but I'll keep my eyes peeled. Thanks for the tip! :D
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I get low 6.x litres / 100 km consitently delivering pizza. I've gotten below 6 litres / 100 before but not lately. There always seems to be a black fog following me around lately too, that cant' be good for mileage. :lol: I'm going through the timing belt fiasco next month so I'll try to tune her a bit better then.
Steve
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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. :D
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:
yea but the paper bag goes like hell when tuned up properly. the Q ship is a nice ride over the road, just not sporty enough sometimes. plus they are great in the snow.
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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:
yea but the paper bag goes like hell when tuned up properly. the Q ship is a nice ride over the road, just not sporty enough sometimes. plus they are great in the snow.
Ok
:D "Drive a Quantum; for those who have time to admire the view"...
"AND feel the need to carry the stage for a gig" 8)
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Hmmm...my Golf is only getting about 30-35 mpg as well, even in summer. Thats 650-700 kms per tank. Not sure about the mechanical condition of the engine. There's some oil in the intake and a bit of blue smoke occasionally, but the power output is good and it only uses about 1/2 litre of oil every 5,000 km.
I've checked the pump timing...it's good. I even tried applying a constant 12V to the timing advance mechanism, and noticed no change in either performance or mpg.
I would like to check the engine's compression, but given the cost of a compression tester, I think I might just try a set of new injectors.
Have checked the obvious things such as air filter, tire pressures, new fuel filter...I do probably 80% hwy and only go 100-110 km/hr. The engine gets up to around 80C in winter and 90 in summer.
It's got 272,xxx km on the clock.
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Hmmm...my Golf is only getting about 30-35 mpg as well, even in summer. Thats 650-700 kms per tank. Not sure about the mechanical condition of the engine. There's some oil in the intake and a bit of blue smoke occasionally, but the power output is good and it only uses about 1/2 litre of oil every 5,000 km.
I've checked the pump timing...it's good. I even tried applying a constant 12V to the timing advance mechanism, and noticed no change in either performance or mpg.
I would like to check the engine's compression, but given the cost of a compression tester, I think I might just try a set of new injectors.
Have checked the obvious things such as air filter, tire pressures, new fuel filter...I do probably 80% hwy and only go 100-110 km/hr. The engine gets up to around 80C in winter and 90 in summer.
That's not very good mileage :(
Whilst I have no experience in your 'electronically advanced' system
what I can say, is my Quantum had the same poor economy when I bought it. The 'faults I found were 1) Pump timing was set to N/A specs.
This may have been due to 2) the cam was about one tooth out on the belt or about 1.5 teeth out on the fly wheel.
(This I feel may have partly due to the PO's mechanic not taking care when tightening up the cam sprocket AND not rechecking after :roll:
3)I backed off the fueling slightly on the 'Spaceship' (LDA) diaphragm.
I then cleaned my injectors with 'Redex' and finally ran the car for a few days on pure cannola which cleaned them up.
I'm not sure that low compression neccessarily leads to poor fuel economy as long as fuel is not being wasted. Shortly I will be checking my compression which I suspect after 160000 miles is somewhat weakened; but the fuel economy is as good as ever and very good for a Quantum :mrgreen:
I've just sorted out a compression tester using the bottom from an old injector and a few adaptors.
Whilst I had a tester with no adaptors; I think something could be made from an oxgen gauge a piece of line and at least one valve to hold the pressure
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dieselweasel
I agree with Mark that 30-35mpg is crap. Are these US or imperial gallons. I can very easily get 1000km on my 94, with 263,000km, if I had the courage to see the needle go into the red. I usually fill up at 850-950km in winter which uses about 45-50 liters of Sunoco diesel.
Do you fill the tank right up to the filler neck or just stop pumping when the pump shuts off? You can get another 6-7 liters in the tank after the pump first turns off. Not sure about your car, but mine has a little vent tab that you can push to quickly get rid of the air in the tank while filling. This would add another 100km to your range.
What kinds of fluids do you have in your car (motor oil, gear oil)? Changing the motor oil to a synthetic 0W-40 or 5W-40 and the gear oil to a synthetic like Redline or Amsoil could give you another 4-5 mpg.
Using a fuel additive might help also?
What are your tire pressures at? and what size are your tires? If you have tires that can safely go to 44psi then put them up close to that. So long as you don't mind the slightly harder ride.
You can also slow down if your not in a hurry. I usually drive in the slow lane (the right lane) at 90km/h, however some idiots always come up behind me at 110 thinking it's the passing lane. Doesn't matter I just smoke them out and laugh, give them the finger (depending on my mood), or the best is putting on my autodarkening welding helmet (they always look freaked out when I do that). I guess an Optrel Satellite helmet does look a little alien like :lol: .
Sorry for the long reply.
By the way, you didn't go to Centennial last year did you?
Peter
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US gallons.
When I fill it up I usually just let it pump one more time after it clicks off. I also have the tab in the filler neck. Have used it before. I calculated my mileage based on the amount of fuel I normally put in, about 48L.
I don't have synthetic engine oil, not sure about the trans. Something I might try though. I'm on winter tires now but it was the same deal with the summer Pirellis. They're inflated close to the max.
I find that going 100-110 is far too slow for many people...I get trucks passing me sometimes!
Thanks for the reply.
I did go to Centennial last year for intermediate Truck/Coach tech apprenticeship training. How bout you?
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dieselweasel
Do you have a white 2 door Golf? If so, I was the guy you talked to last year in the back parking lot. I had the silver 94 Golf. I'm finishing the automotive technician course this April.
When you do fill up, is the needle in the red marks yet? I'm thinking that my fuel gauge might be a little off but I'm not sure.
Can your tires go up to 44psi or are they the 35psi types?
Peter
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Yeah I remember you...I have a 4 dr actually. How did you know? You must remember me complaining about my mileage! Good memory.
I always fill up with the needle in the red. The tires I think will go up to 44 psi. You know what, tonight after work I'm going to check/adjust the pressures since I haven't done that in a while. Thanks for reminding me.
What I'm going to do I think is remove the injectors and get them tested by a diesel shop.
Hopefully I'll be going to Centennial for advanced this year. Anyway, good luck with your automotive career.
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The other thing you should check tonight is the air filter. A diesel (any internal combustuin engine actually) is a big air pump. If you don't get enough air into it, it will run too rich(burn too much fuel). Good luck!
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Good point Patrick
Which reminds me, dieselweasel do you have the snorkel attached to the airbox. It goes from behind the front bumper to the airbox. Theres a screen in there to catch large objects and it might be plugged up and restricting airflow. I took that out completely and cut out the front opening in the airbox as much as I could. It's about a 8" X 3" opening compared to the 2.5-3" hole that was there stock. I'm only speculating but I imagine that the engine can now get a whole lot more air. I do have a K&N air filter too.
Damn I seem to remember it was a 2 door. So much for good memory I guess. I remember seeing a white 2 door Golf at school, it was probably a gasser then.
Thanks.
Peter
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The other thing you should check tonight is the air filter. A diesel (any internal combustuin engine actually) is a big air pump. If you don't get enough air into it, it will run too rich(burn too much fuel). Good luck!
:twisted: Ah that reminds me...My final mod wasto run with a cloth filter
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what's even better is buying farm diesel (dyed pink/purple) for around 60 cents a litre, AND getting 50 mpg :D
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my 93 td that gets 6-7L/100km has brand new injectors, 5-40 synthetic motor oil, synthetic amsoil tranny fluid, and 16" rims with 205/40 series tires with 30 psi in them. K&N panel filter. Only thing I can think of in my case is it's getting close to time to change the fuel filter, and I'm getting my clutch done as we speak, with lightened flywheel, i'll let you know how that goes.
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my 93 td that gets 6-7L/100km has brand new injectors, 5-40 synthetic motor oil, synthetic amsoil tranny fluid, and 16" rims with 205/40 series tires with 30 psi in them. K&N panel filter. Only thing I can think of in my case is it's getting close to time to change the fuel filter, and I'm getting my clutch done as we speak, with lightened flywheel, i'll let you know how that goes.
We're in the same boat then. Have you checked your pump timing?
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Those 16"wheels and tires are hurting your mileage. A set of cookie cutter 13's (lighter and narrower) would make a big difference. You'e got a lot of wieght to spin, and a wide tire topush over the road. .
I'll bet they look good though............
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my 93 td that gets 6-7L/100km has brand new injectors, 5-40 synthetic motor oil, synthetic amsoil tranny fluid, and 16" rims with 205/40 series tires with 30 psi in them. K&N panel filter. Only thing I can think of in my case is it's getting close to time to change the fuel filter, and I'm getting my clutch done as we speak, with lightened flywheel, i'll let you know how that goes.
We're in the same boat then. Have you checked your pump timing?
nope, i'll make a note to have my mechanic look at it when he hooks up my intercooler and ups my bosot etc very soon.
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heres mine:(US milages) 35mpg (14.8km/l) winter, 40mpg (16.9km/l) average, 45mpg (19.0km/l) best milage ever
i got 185/70r13 tires, .038" (.97mm) on the timing, fueling screw and smoke screws backed off so the cars acceleration sux, lots of new suspension parts, timing belt, 5w-40 syn oil, etc Id figure my milage would be a bit better than it is. It would be nice to turn up the fueling screw a bit so the car has better acceleration but im afraid to drop to like 30-35 if i do.
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what rpm are you guys turning at 65, 75 in 5th gear? also what motor and n/a or turbo?
mine is a 1.9 eco and am trying to figure out what gears i need to get it near stock rpms
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you guys really need to try power systems diesel fuel conditioner--more power and more mileage. 45 bucks at 86 cents a litre and did a 1200 km trip with fuel to spare :)
calculated out thats around 4.3L/100km. Without the fuel conditioner I average around 5-6L/100km.
oh and btw, my motor has bad compression and needs valve shim job.
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jtanguay, i do use that stuff plus antigel in winter. Every tank i put it in per instuctions - 1oz per 3 gal in summer and 1oz to 1 gal in winter.
My rpms at 65mph are about 3000 and at 75mph about 3400
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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?
do you actually put motor oil in your tank? Is this good for the engine? I've heard of people putting ATF but not oil.
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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???
I think people exaggerate. My 1.6TD is getting 48mpg right now (mixed highway and city driving) and would get 50mpg if the return lines weren't leaking. I had a diesel rabbit that approached 60mpg. But never heard of, or owned a diesel VW that could get 75mpg. Ever. Perhaps the Lupo could do that, but they don't import them to North America.
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what's even better is buying farm diesel (dyed pink/purple) for around 60 cents a litre, AND getting 50 mpg :D
where do you buy this?
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where do you buy this?
You get a storage tank and buy it in quantity from your local fuel supplier under the pretense of using it in off road equipment. The road tax is not assessed on the fuel, thats why its cheaper. The red colouring is added to identify the fuel as non-taxed. If you happen to get caught running off road fuel in a road vehicle, the fines are hefty.