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Engine Specific Info and Questions => IDI Engine => Topic started by: ejust on June 28, 2005, 03:08:03 am
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i dont know how you guys do it..i cant seem to get over 40-45 with my TD
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with my little NA 1.5 i got 51 mpg on the last 2 fill ups
the diesel that i have sat for a long time and the milage has gotten better the more i have driven it, (i started out at like 41 mpg)
but on heated veg oil i only get like 40 mpg
later
justin
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i dont know how you guys do it..i cant seem to get over 40-45 with my TD
my latest mpg was 52. (88 Jetta TD)
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86 Jetta TD, last tank, 561 miles, 11 gals exactly = 51mpg. My Pickup gets 48-50 consistantly.
Check your compression and timing. Does it smoke black much? Keep your top speed under 60.
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86 Jetta TD, last tank, 561 miles, 11 gals exactly = 51mpg. My Pickup gets 48-50 consistantly.
Check your compression and timing. Does it smoke black much? Keep your top speed under 60.
He's right about top speed. If I travel at over 120km/hr my fuel mileage decreases by 3-4mpg. Key is to keep the engine under 3000rpm. It isn't very fuel efficient over that rpm threshold. I am able to get 52mpg in stop and go city driving, in downtown Toronto, as long as I don't accelerate too quickly and I keep the rpms below 3000 always.
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i travel at 65-70mph (105-110km/h) on the highway (3200rpm) and in town i dont step on it. As stated above, my compression is fine and only a very light puff at full boost. I have the fueling turned back on the car. I just checked the timing on he car and as stated above..its .040"(1.01mm)
So i dont know why i get 7-9mpg less than everyone else. I very fuel cautious due to the prices. And it seems to get it best milage at 3-3200 rpms
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Are your tires inflated on the high side? I keep mine at their max on their side wall. 40psi.
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tires are inflated to 35psi...thats max pressure on them
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just filled up today - 266mi on 6.90 gal (428km on 26.1L) equals 38.5mpg (US)(16.4km/L)
thats was 104 city miles and 162 hwy miles at 65-70mph (about 105km/h)
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Yeah....well at last fill up I got 587km out of 10.4 gallons which is roughly 35 mpg. I think between between my fuel being turned up really high for a while, and my cruising at around 120 kph I must have hurt it pretty bad. I think it's time for more boost.
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1989 Caddy 1.6D N/A 255K on the clock.
Driven like a idiot, daily.
Fuel screw out a little, bit hazey up top.
'round town - 43mpg.
on a run, a bit more!
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just filled up today - 266mi on 6.90 gal (428km on 26.1L) equals 38.5mpg (US)(16.4km/L)
thats was 104 city miles and 162 hwy miles at 65-70mph (about 105km/h)
well, diesel dawg, that mileage is way too low. You could check things like: brakes: do they release or are they dragging, thermostat: when is it open. If it opens too soon the engine will run cold and your mileage will suffer badly. Transmission: what sort of fluid do you have in it, how old is it? Rad fan: does it run all the time. This is a major electrical drain and causes you to lose fuel economy. Air conditioning: do you have it, is it turned on? This will affect mileage significantly.
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in answering the above questions....
i did a brake job last fall and put new pads/shoes on all four corners. Seems to coast pretty nicely so im kinda thinking its not the brakes. Theres a new t-stat in it. 180 degree F(82degC). Temp guage is between 1/4 and 1/2 running down the hwy. i had a 192F (90C) in there but guage was high then (1/2 to 3/4) and the fan came on all the time.
Tranny fluid - 75w-90 mobil synthetic
Fueling is set that it barely smokes at WOT an no boost and a light haze at 5+psi bost
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Have you had your alignment tire balance checked lately? Is your air filter clean? Do you know that your exhaust is flowing freely without any clogs? Have you tried fueling at different locations?
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alignment done last november after i redid the suspension
air filter changed <500mi (800km) ago, thought that might have been a problem but i guess not
exhaust plugged? i dont think so... turbo winds up like normal (starts spooling at about 2-2500/full boost of 9psi)and can feel exhaust outta the pipe
as far as the fueling...as stated above..right now i have it set at light smoke at WOT and no boost and a light haze at 5psi+ (<--normal?)
ive tried it at.... 1) no smoke even at full throttle and boost (<-- very doggy)
and ive tried..
2)smoke like crazy even with 9psi boost and the LDA disconnected (<--mosquito fogger)
#1 didnt seem to increase milage but maybe a mile or two tops
#2 didnt run it long enuf - but would figure a big drop
Can too little fuel cause poor milage?? I wouldnt think so....trying to keep smoke down not to fog out people behind me.
The car cruises ok, runs and starts fine. Not real zippy even with full boost but i figured thats normal for these cars.
How can you tell if your opening pressure in the injectors are dropping? Maybe nozzles going bad??
I have no way to test and the nearest place thatll test my injectors (bosch sevice - no one else does servicing locally) is 150miles away.
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bump
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If your engine is smoking, it is not burning all of its fuel. Smoke is uncombusted fuel, after all. To be more efficient you want to run it lean so that it does not smoke at all. The most efficient torque for a factory motor is about 80% of factory max torque setting (it would be even less than 80%, if you've modded the pump to the point where you can get lots of smoke.)
Have you considered it could be the way you drive or the routes you are driving? Using brakes a lot bleeds off kinetic energy which must be regained by burning fuel to get your car back up to speed. So, driving in a way where you do not use your brakes as much, for example anticipating stop lights or allow traffic to cut you off and make you use brakes, will result in better fuel economy.
Also, it could be the way you or others are measuring their miles per gallon. The method used to measure miles per gallon can also make mileages vary. The most accurate way is to measure fuel consumed over a number of tanks and average the overall amount of fuel consumed over the total number of miles traveled - figures recorded over just one tank will not be highly accurate because the tank will not be refilled to the exact same level. Furthermore, odometers are often miscalibrated, and can contribute additional inaccuracy to fuel mileage readings.
Bottom line - YMMV, or "your mileage may vary", applies when comparing fuel mileage numbers. There is not necessarily anything wrong with what you've measured, especially if you drive in an area with traffic and frequent stops or frequently use high speeds on the freeway.
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I just filled up again today. Mileage is back up now that I turned the smoke screen off. 41 mpg in my 88 Jetta TD.
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Do you have a lot of miles on your injectors? Getting them rebuilt could certainly help. This guy will do a superior job, and you can tell him that you want the injectors set up for maximum fuel economy.
http://www.coloradobiodiesel.com/injectors/index.html
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the odometer on the car shows 222k mi (357k km). When i bought the car, the guy told me that at around 140 to 150k mi(225-241k Km), the dealership put a new timing belt on, but i guess timed the engine wrong so the valves contacted the pistons. he said the dealership had to replace parts. Which ones besides valves i dont know. So im not sure which engine parts are original and which one have about 75k on them. My compression test last fall (engine cold at 50F (10C)) was as such
#1 - 445 #2 - 485 #3 - 465 #4 - 440
So compression seems to be ok. When i start the car cold, there is a hint a bluish smoke but its really faint which i figured is normal for diesels and it goes away in a couple minutes. It starts right up - almost faster than most gassers. Im thinking maybe the fuel system is original though so imagine the injectors and pump have the 222k on them.
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Probably time for new injectors -- they can help out enormously.
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im getting 800kms per tank in city traffic in my 89 N/A
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topped off again at the same point as last time....
124mi on 3.25 gal = 38.2MPG
about the same as last time....
and the time before...
and before that.....
guess mine dont like 40mpg or better..and its not that zippy either :cry:
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53.6mpg recorded today (US gallons), after two weeks of city driving. 1988 jetta TD. This car is AWSOME!
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must be nice. dont understand whats going on. Even the bentley says i should be gettin 44 or above. :cry:
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ejust try getting your car re-timed. Some people say changing the transmission oil to synthetic helps too. You also have to watch the way you drive.. try to keep rpm's below 2000 and your mileage should be really good. There is also some diesel additives such as cetane boosters. Those help a lot :).
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im thinking there is something shot. Has to be. Ive fixed up the car and made sure everything thats adjustable is basically to specs inc the timing is dead at .040 (1.01mm).
Ive noticed oily specs in my coolant. Ive done a couple flushes but it keeps coming back. Thinking the head gasket is going. And that might be my problem.??? How long before it totally goes?? I think injectors need redoing. So i guess ill have to just deal with it all inc the bad milage till i can afford to get all this done.
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it shouldnt be the head gasket, i drove mine whaile the geasket was shot and i still got 800+kms per tank
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Just a thought... but could it be because the compression is so high, that it is actually creating parasitic drag on the engine at high rpm? ie: the compression stroke is robbing the power stroke of energy? Or would that even make a difference? It might explain why oil is seeping into the coolant, mainly because of all that pressure.
If everything else is good like tire pressure, alignment, wheel bearings, no brake drag, and good suspension, then who knows...
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first off..I wanna say thanks :wink: to those who have helped me here on IDI. I know a ton of questions come in like i do about "my car" and ask specifics. I hope to gain the knowlege to be able to help someone else out someday!
This whole site is great and kuddos to the owner/designers/moderators!!
Ok..back to my dilemma LOL
high compression..im gonna rule that out Reason being..at 23:1, the cylinder pressure is suppose to be between 400-500psi normally. Ive read so far that high boost can cause extra pressure which basically lifts the head off the gaskets microscopically and allows escaping gases. My head gasket could very well be doing that even though my setting are stock. Just a guess here. Ive noticed its not as powerful as last summer, zippy when cold but loses power when it warms up, temp guage hovers around 1/4 (maybe 1/2 after lots of driving then sitting and idling), and milage is averaging around 38ish which is low. Bently says 44mpg(US) in mixed traffic above 32F (0C). Going up a small hill i can step on it, itll smoke behind me but not real bad, but it the car hardly accelerates. Losing power somewhere. Ive tried setting the pump per the book for residule and idle settings.
Question..would a govenor mod kill milage?? I cracked open my pump 3 weeks ago and attempted fait. The govenor had like washers or something and springs. Dont know if it was tampered in the past but doesnt look stock or like a complete mod from what ive read. Intermediate and main springs look like it has 1/4" (6mm) of washers or something. What would that do to affect the car? Ive left it for now before either i put it back to stock or change it to complete mod and remove intermediate spring. Anyways, its back together and car is running the same so i must of not screwed anything up LOL What a pain the throttle springs are!
ive rambled enuf for now. Y'all can dissect this and hand me your opinions and expertise on this. Thanks again everyone!!
i wish i had a injector pressure tester. That would give me an idea here if those are good or not.
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Power when cold.. but less power when warm... sounds to me like my old car. I think it was either the injection pump, or the cold air filter I threw in (heatsoak)
btw yes the compression is 23:1 so that means if you're boosting 10 psi then magnify that by 23... so that is an added 230 psi once fully compressed. Obviously that is a heck of a lot of pressure and some of it is going to escape somehow. I'd say get a metal head gasket and that might help?
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ive got the stock snorkel and air filter on mine so heat shouldnt be problem as far is air intake.
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I would definitely consider an injection pump rebuild then, or injector rebuild.
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Question..would a govenor mod kill milage??
I don't think so. The governor just kills the fuel supply above 4000rpm. Most likely you never run your car above that anyway. People just do that modification if they want to race their cars and they need to run the engine at max power output.
Adjustments to the fuel supply can kill mileage though. If you adjust it and get a lot of smoke, then that is your fuel going out the back of your car.
Temperature definately kills power output on those cars. Hot air has less density than cold air does, so less air molecules get into the cylinders when the air is hot. The turbo is right next to the exhaust so the air can get pretty hot. This is why intercooling the intake air is such an improvement on these cars.
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well, i did govenor mod. Actually had the guts to do it. Damn throttle springs are a pain to get back on, but i figured it out. Definitely zippier. i can see between the gov mod, more fuel, more boost, and intercooling why you racers have fast cars.
heres what ive come up with...
the mod increases fueling/pressure which increases the smoke out the tail pipe
I tried to back off fueling to not have a cloud. But my idle is low and the adjustment is all the way up. I can turn the fuel back up, be able to raise idle to normal, but then i mosquito fog and watch my mpg drop. I did the mod to have a tad more zip around town. Maybe a partial mod would be better. i dont know.
My milage is still low by Bentley standards. All city driving - 33mpg (14km/L), 50/50 - 37-38(16km/L), all hwy - 42mpg (18km/L)was the best ive ever had at 65mph (105kmh) steady.
I really hope to get an intercooler maybe that would help. Im sure my injectors need rebuilding. Who does that sort of work for a really good price? Im sure i can replace the nozzles myself, but the pressures will need adjusting.
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cant get the idle to stablize now. if i dont had the residule adjustment up, i wont stay running, but now the idle is like 1200. The actual idle adjustment isnt enuf. I think im gonna go back to the normal stock setting (if i can find them again).
I think an injectior is going personally. Doesnt seems to have the power it used to at all. Fairly doggy. Plus the oil in the coolant scares me. MPG still averaging around 38mpg (US). Oil pressure at idle - 10-12psi (vavle lifters ticking hard) Sigh.........
After all the work last fall on the suspension, guess now i gotta stick a ton more money into this car for the enigne/fuel. Getting about ready to sell this darn thing! Engine rebuilds arent cheap!
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I got a few questions about my car as well. I just got a 1996 vw jetta with a 1.9TD and I am wondering what would cause my poor mileage which is around 7-8L per 100km, the car has 196000km on it. I know right now that the alignment is off and that when my dad put on the timing belt that the injector pump was "close enough" which means it is out of timing by 1 tooth. I am thinking of getting back in there are timing it properly, would the pump being out of time effect mileage much? I am also wondering how much of a different getting new injectors would make. There is also sideways play in the turbo spool and I know that if the turbo isnt working properly that your fuel mileage would go down, can you get rebuild kits for the turbo or do I have to get a new or remanufactured one?
Thanks
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I would the pump being out of time effect mileage much?
There is also sideways play in the turbo spool
Thanks
Improper pump timing will definitely have negative effects on fuel economy. You want the pump to be timed to the more advanced side of spec for best mpg. Check pump timing before going any deeper.
Sideways, or radial play in a turbo is ok as long as the compressor wheel isn't hitting the housing. If there's axial or end to end play, the turbo should be replaced.
Ejust - You should remove the injectors and get them tested at a fuel injection shop. I got mine tested for free.
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where y'all get 'em tested for free?? There aint no one within at least 150mi (240km) that would test them for free. The nearest place that can even test them at all is 60mi away and it would cost around $40US just to test it. No other work done. :(
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I get mine tested locally, for free too ... well I bring them baked goods, donuts and cookies.
They are going to test a set I dropped off last week and set them to the right pressure.
What is the suggested breaking pressure?
The '84 Bentley says 1706 - 1849 for the NA diesel and 2030 to 2200 psi for used turbodiesel injectors.
Anyone think different?
What happens if I set them for turbo diesel and use them in a vegy burning NA diesel?
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maybe i could send them to you and you could get them test and reset for me LOL Then ill change my head gasket at the same time
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well fatmobile I think the veggie burning NA with some turbo injectors would run pretty good since the veggie oil is thicker :)
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I've heard bumping the pressure up helps with the spray pattern when running on vegy, not sure if they were doing this with special injector inserts or what effect it had on fuel mileage.
If no one on here knows for sure, off the top of their head, what a good vegy injector breaking pressure is, I'll have to do some searching. Maybe something less than the turbo diesel injectors.
maybe i could send them to you and you could get them test and reset for me LOL Then ill change my head gasket at the same time
Better send some dounuts too, ha.
I'm expecting to be charged for adjusting the breaking pressure, that could take some time. He checks for breaking pressure, spray pattern and drips etc. in about 5 minutes.
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At that time of day(night?) on a weekend, wouldn't beer be a better motivator? :lol:
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I know what he eats but am not sure what he drinks, ha.
Shortly after I posted that, a fight broke out at the bar and I went down to hang out at the closing time freakshow.
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Hi all,,,, so last wk I played hooky from wrk and drove the frankenbunny to Yosemite ( tuallomy medows) .It's 499.5 miles from Sonoma to the park and back...... the trip up took 9.5 hrs because of slow an' stop traffic from Napa county line to Mantica !!!!!!!! I fumed all the way ...cause I knew my milage was going to suck from all the time spent idleing or creeping in 1st gear . any how ,,,,, up to the campground, find son and mom (They spent the week!!), stay night, pack up and back to sonoma.... gas up in Mantica ..... and back at the cheep station in Petaluma..... 9.2 gal for the trip !!!!! figureing milage,,, 54.6+ on the way up, and 53.5 + on the way back (less traffic , but still under 55 mph) I still get 43- 47 on my comute from Sonoma to Treasure Island. :D
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my car must be a p.o.s. then.
now the damn thing i cant get it to idle under 1100 r's without dying
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now it wont idle below 1100 with out stalling out soon as i turn down the idle or residule adjustments, it slows down, and within a couple secs just dies. itll restart, but if i dont hold the throttle just a tad, itll die again
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