VWDiesel.net The IDI, TDI, and mTDI source.

General Information => Troubleshooting => Topic started by: xxkoadyxx on January 28, 2011, 10:13:50 am

Title: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 10:13:50 am
I have a 93 1.9td with 376'000kms on it, it seems to be getting poor fuel millage as im only getting about 500km-maybe 600 kms.. this is with super easy driving..it has a new air filter on it as well that i put on before winter as i use a cone one in the summer..idk what else could be the problem.....anyone have any ideas??

THANKS
Koady A
Title: Re: causes of low mpg on 1.9td
Post by: R.O.R-2.0 on January 28, 2011, 10:20:26 am
im sorry im a stupid american..

whats that in MPG?

have your pump and injectors ever been serviced?
Title: Re: causes of low mpg on 1.9td
Post by: Vincent Waldon on January 28, 2011, 10:25:05 am
If that's winter city driving in a cold part of Canada that's not actually too bad... winter diesel has 10% less energy than summer diesel and stiff oil/tires/bearings/snow can easily drop your winter another 10%.  A 15-20% drop in fuel economy over the winter is very typical of diesel-engined cars.
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 10:30:20 am
alright so about 21-25 mpg if it has a 14.5gallon tank.. im not sure as that was for a 2.0..couldn't find specs on  a 1.9td fuel tank..
the injectors or pump has not been sense i owned it..2 years..Also i wouldn't get  any higher then 600 in the summer, no matter how hard i tried.
Title: Re: causes of low mpg on 1.9td
Post by: R.O.R-2.0 on January 28, 2011, 10:32:09 am
!!! omg.. thats terrible..

i wonder if the advance mechanism in your pump is stuck?

or if your injectors are soo crappy they barely atomize fuel?
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 10:35:18 am
im not sure, the rpm doesn't change when i pull the cold start out.idk if its suppose to or not, i know it does on my bros 1.6td. how would i check the injectors? what does it mean to atomize the fuel? would that reflect poor mileage?
Title: Re: causes of low mpg on 1.9td
Post by: R.O.R-2.0 on January 28, 2011, 10:49:36 am
is a solid stream of fuel going to burn easier?

or tiny little fuel droplets?

injectors spray a super fine mist of fuel when they are operating correctly.

if they have clogged nozzles, or broken nozzle tips, they shoot a stream, or just half ways atomize the fuel..

and your idle should definitely increase when you pull the cold start knob..
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 10:59:01 am
so how would i get my injectors checked? go to a diesel mechanic and get them to test them? what would i have to do about the cold start?
Title: Re: causes of low mpg on 1.9td
Post by: coke on January 28, 2011, 11:01:19 am
Someone you know who has a pop tester can test them for pop pressure and spray pattern. Alternatively, you can go to any diesel service center that can test bosch fuel injectors.
Title: Re: causes of low mpg on 1.9td
Post by: R.O.R-2.0 on January 28, 2011, 11:02:14 am
anyone with a pop tester could test them..

and as for the cold start, it may just need an adjustment on the rod that goes from the cold start lever to the pump top..

or your pump could be so far worn out that it cant build any internal pressure, and cant move the advance piston.

even then, it should still change engine sound slightly when you pull the CS cable, even if it doesnt kick it into high idle..

does it rattle any more when you pull the cable?
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 11:08:23 am
alright ill look around for someone with a pop tester.. well when i pull the cold start out it does start the car a lot better, just the rpm doesn't seem to change when i put it back in.
Title: Re: causes of low mpg on 1.9td
Post by: Vincent Waldon on January 28, 2011, 11:12:50 am
well when i pull the cold start out it does start the car a lot better, just the rpm doesn't seem to change when i put it back in.

If the car starts noticeably better with the cold start out our cold start lever is probably working just fine then... some pumps have a fast-idle feature but lots don't.  Or you may have one but it's not adjusted properly.
Title: Re: causes of low mpg on 1.9td
Post by: theman53 on January 28, 2011, 11:28:17 am
My car didn't pull at all. I had to do all new front end parts and have it aligned. THis is my first tank through since the alignment, but I bet I will get 3mpg better. Alignment makes a big deal.
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 07:55:15 pm
right now im at 1/4 tank and only got 435kms..i dont wanna do allignment as im getting coils in future and dont wanna do it twice :p.my car has 11psi boost.
Title: Re: causes of low mpg on 1.9td
Post by: catlin_cava on January 28, 2011, 08:01:53 pm
Koady, its the winter, my TDI went from 1200 to 700 to 800 a tank, The City is also WAY down, about 300 to 500kms at the most.
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 28, 2011, 08:30:30 pm
but i can hardly get 600kms to a tank,mostly highway.. i drove from newglasgow to syndy and back and didnt know if i was gonna make it back home cause it was on empty once i got back to town and i filled it up before i went..this was in the fall[sept]
Title: Re: causes of low mpg on 1.9td
Post by: 8v-of-fury on January 28, 2011, 08:55:07 pm
Fuel filter, oil weight, warm up times, pump wear, fuel leaks, worn injectors, ***ty compression, heavy right foot, dragging brakes, seizing bearings,

All can contribute to low mileage.

I dunno man.. 21mpg though!?

Here's a cool TIP! I just did an alignment literally at 5:30pm today before leaving for toronto (130kms) because i replaced a wheel hub last week. Take a tape measure and meausre the same point on the front and back of the tires. If they are within an 1/8th inch tighter at the front than the back its desirable.
Title: Re: causes of low mpg on 1.9td
Post by: Wayland on January 28, 2011, 09:23:24 pm
Does the car start easily? Smoke or knock alot? If not these can indicate bad injectors. They actually have to be really bad to make mileage much worse. Poor compression will cause motor to miss a bit when first started. have you checked you static pump timing? This can effect fuel mileage too. As far as the rpm not speeding up, you may have a vacuum controlled fast idle (my 93 Passat does) that's not working.
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 29, 2011, 04:21:34 am
well i usally plug my car in in the winter, but it starts right up.it blows white smoke while its cold then when it warms up it goes away.usallly starts right up anyways  without being pluged in, as i got 3 new glow plugs.its vacuum controlled i belive. and its not my right foot lol cause i have been super easy on it to see how much i can get out of her. ill check the bearings, brakes.. im running 5w40 mobile one oil and my car doesnt burn it at all.
Title: Re: causes of low mpg on 1.9td
Post by: catlin_cava on January 29, 2011, 04:58:59 am
Does the car sound like its at a high RPM when Running? I know you can't check since you don't have a tach. I had an MK3 AAZ before and i was lucky to get 600 out of it because the gearing was messed up and I was revving high all the time. YOU NEED a cluster with a tach, Its plug and play in your car and 6 screws to change.
Title: Re: causes of low mpg on 1.9td
Post by: wolf_walker on January 29, 2011, 08:54:58 pm
I know it's only semi-related, but the brand new 1.9L TD long block we bought way back and put in the lightweight Caddy pickup never got over the high 30's, and usually the low side.  It's been a TD, a NA, had a brand new, not reman, NA pump, a dual outlet exh mani, new injectors twice, anything and everything else we have ever, ever done to VW diesels over many years of ownership, and it's never been better.  Power is great, compression is fine (it was new) and it's got close to 200K I guess on it now, seem to just be the way it is with this one.  I gave up.  It's quick though..  :)
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 30, 2011, 05:38:00 am
quick? yea mines not quite :( i mean if i was making more power or somthing it would be understandable, but im not, shes all stock.. i turned up fuel once, the rpm went up like its suppose to but i never seen any smoke :s so i just turned it back down :P also would the fuel filter affect the millage? to me, if a fuel filter was bad, it would just burn less fuel.....im prob wrong.
Title: Re: causes of low mpg on 1.9td
Post by: xxkoadyxx on January 31, 2011, 11:49:44 am
can i restrictive exhaust cause bad fuel milage? mine got bent last year when i had to get it towed to shop, and when  they were backing it up onto the lift, the muffler hit and bent it...
Title: Re: causes of low mpg on 1.9td
Post by: wolf_walker on January 31, 2011, 03:49:33 pm
If it's restricted enough, sure.
Title: Re: causes of low mpg on 1.9td
Post by: catlin_cava on January 31, 2011, 03:59:13 pm
I think your IP is going, if you turned the fuel screw up and only raised the RPMs and no smoke, it might be the problem. Send Giles at performance diesel injection an email about it and He'll know for sure.