Horrible Fuel Economy In City

shutout31

Veteran Member
Joined
Sep 27, 2004
Location
Calgary
TDI
2004 Jetta Wagon TDI 380k+ KMs
My 98 Jetta Tdi has been getting horrible fuel economy in the city lately. I drive fairly respectivily but like to put my foot into it every now and than but can't get more than 400km of strickly city driving. To school and back pretty much. On the highy way i can get around 900km, to a tank. Is something with my car? i know it is winter and fuel economy goes down but even in early november it was this bad also. what can i do to fix it? Thanks
 

shutout31

Veteran Member
Joined
Sep 27, 2004
Location
Calgary
TDI
2004 Jetta Wagon TDI 380k+ KMs
Yeah i usually let the car warm up for 10-20 minutes. the commute isnt far average i probly do 20-50km a day
 

jnecr

Veteran Member
Joined
Oct 9, 2004
Location
Raleigh, NC
TDI
2014 BMW 328d
Well, there is probably some cleaning you need to do of the snow screen and intake...

You say that you let the car warm for 10-20 minutes? Do you mean at idle in the driveway? TDI's won't warm up without being driven so don't let you car idle for that long, it's quite useless. I would say that your problem is a combination of a dirty intake and cold weather. You will get horrible mileage when your engine is not warm. There's not much you can do about that really...
 

shutout31

Veteran Member
Joined
Sep 27, 2004
Location
Calgary
TDI
2004 Jetta Wagon TDI 380k+ KMs
somewhat of a stupid question but how long do yo usually let it yours warm up in the winter? below 32?
 

jnecr

Veteran Member
Joined
Oct 9, 2004
Location
Raleigh, NC
TDI
2014 BMW 328d
When it's below freezing, I'll cycle the glow plugs twice and then start it up. I'll drive away once the idle isn't rough anymore (30 secs max). These engines don't burn enough fuel at idle to ever warm up. In fact, in cold weather, they will cool down at idle...

It was only 25 degrees F here in North Cakalack and it took 15 mins of in town easy driving before it was near the 190 mark on the temp guage. I can't imagine driving one of these in the north.. cold!!
 

shutout31

Veteran Member
Joined
Sep 27, 2004
Location
Calgary
TDI
2004 Jetta Wagon TDI 380k+ KMs
I have a tdi heater installed so it makes my engine start with no problems. i usualy let it run for 10-20 while i have breakfast and than go to class. I noticed that if it is running while im in a store quickly the engine will cool down if its un level 4 heater. but on 2 it doesnt drop to much. We just had a cold snap that we hit weather -45,-48 degrees celcius. and the car started no problem with The TDI heater
 

jnecr

Veteran Member
Joined
Oct 9, 2004
Location
Raleigh, NC
TDI
2014 BMW 328d
Well I would say that you need to do some snow screen cleaning. I'm not sure where the link is to that, you may want to do a search for it...
 

shutout31

Veteran Member
Joined
Sep 27, 2004
Location
Calgary
TDI
2004 Jetta Wagon TDI 380k+ KMs
well i took the airbox and everything out and the bottom of the air box had to inlet pipes. one which is permanelty open and the other that has the trap door, the door has a foam filiment kinda thing on it so i just cleaned that a bit and pieced it back together. but im going to do a 1700km round trip on wednesday and see if my hwy mpg goes up
 

TDA

Veteran Member
Joined
Oct 6, 2002
Location
Hamilton, Ontario
TDI
None anymore
It was only 25 degrees F here in North Cakalack and it took 15 mins of in town easy driving before it was near the 190 mark on the temp guage. I can't imagine driving one of these in the north.. cold!!
Let's see if I can conjure some imagery for you. At -15 F and 50 MPH for 30 minutes, the temp gauge doesn't climb past half way to normal. 95 F, if it is linear. You can't leave the cabin fan off until the engine warms, because your breath will frost the inside of the windows. You can't put the cabin air on recirculate when the engine is warming, because the windows will fog up. About 20 minutes into the drive, you're thankful for incoming air around 32 F.

My heated seat stopped working, but I'm not complaining. It doesn't get really cold here.
 

jnecr

Veteran Member
Joined
Oct 9, 2004
Location
Raleigh, NC
TDI
2014 BMW 328d
It was only 25 degrees F here in North Cakalack and it took 15 mins of in town easy driving before it was near the 190 mark on the temp guage. I can't imagine driving one of these in the north.. cold!!
Let's see if I can conjure some imagery for you. At -15 F and 50 MPH for 30 minutes, the temp gauge doesn't climb past half way to normal. 95 F, if it is linear. You can't leave the cabin fan off until the engine warms, because your breath will frost the inside of the windows. You can't put the cabin air on recirculate when the engine is warming, because the windows will fog up. About 20 minutes into the drive, you're thankful for incoming air around 32 F.

My heated seat stopped working, but I'm not complaining. It doesn't get really cold here.
No more imagery please...
 
Top