Horrible Fuel Economy! HELP!

Kamil · 09-11-2012, 12:46 PM

I have a 2000 323ci that just hit 210,000kms... Full tank runs me roughly 85$ and even when i drive like a granny I get a maximum of 400kms. No engine codes and i dont smell any gas when the car is running so im guessing the O2 sensors are still good? Thinking of changing the fuel filter, cleaning the intake, changing spark plugs and I already ran a full fuel system cleaner once with no better results. What do u guys recommend to change?

andrew.k · 09-11-2012, 02:38 PM

Fuel filter may be clogged. I would start there.

Ceeker · 09-11-2012, 02:49 PM

a tune up would be ideal..lol...

jabela · 09-12-2012, 11:10 AM

When was the last time you changed your air filter and spark plugs?
Also check to be sure your brakes aren't dragging.
Running some injector cleaner wouldn't hurt either.
Do you ever run your engine hard like a track day or something? It can help to burn off excess carbon buildup. My car always feels smoother and more powerful after a track day.

**T.Dot_E30** · 09-12-2012, 11:19 AM

Is all your driving city driving?

pawcio · 09-12-2012, 11:42 AM

Quote:

Originally Posted by T.Dot_E30

Is all your driving city driving?

good point.

your tank is 63L, reserve is 8L so if you tank up when your light comes on that's around 55L which works out to 13.75L/100km or 17.1MPG if you get 400km on a tank.

323i has a combined fuel economy of 20MPG (17MPG city and 26MPG highway).

so if you do mostly city driving you're in the right ballpark.

I do a combination of city and hwy driving and i get a little over 500 before my light comes on (which works out to 10.8L/100km or ~22MPG)

jabela · 09-12-2012, 12:11 PM

I have a 325ci and I do 70/30 hwy/city and get about 9L/100km.
When I do a lot of city driving I get about 10L/100km.
I also have a 5spd manual. Are you driving an auto?
If I drive economically, I can get 7L/100km on the hwy and 9.5L/100km in the city.
Are you using the correct oil? ie. 0w40 Mobile 1 or 0w30 Castrol?

uzi577 · 09-18-2012, 03:44 PM

If you really want to improve your fuel consumption, you have to replace your O2 sensors, just the 2 in the engine bay. However the are relatively expensive. So calculate if it worse it.

blakneto · 09-18-2012, 11:17 PM

The numbers aren't too bad...
Some of the obvious...

Clean your MAF?
Change your Air Filter?
Driving habits?
PCV leaking? (oil separator)

Good? Bad? Ugly?

Kamil · 09-19-2012, 08:13 AM

I cleaned the MAF, cleaned the cone filter, about to do a fuel filter today or tomorrow, ran injector cleaner once about a month ago, and thinking of doing the o2 sensors. It is manual and i drive it religiously cuz the car is so low i dont go over the speed limit and shift around 2000rpms usually with the rare little pull ill give it now and then. wow 17mpg is pretty horrible for a 2.5L :O what does the 330 get lol, 13mpg?

LOSO · 09-19-2012, 10:38 AM

You haven't told us if that 400 km was from city driving.

blakneto · 09-19-2012, 11:50 AM

If I do highway+city driving and drive the car HARD, I'll get about 425km a tank.
If I drive nicely, I get about 600+ km. (Highway+city)
If I drive nicely on the highway, I'll get 700+ km sometimes 800+ km of highway.

knightowl · 09-19-2012, 02:32 PM

sometimes shifting at 2k is too early, I wouldn't shift before 2500. optimal 2500-3000 if your slowly accelerating. when you shift at 2k, your RPMs drop to 1500-1700 and the car would be struggling to keep up and thereby probably needing more fuel to keep up.

I had huge issues with my o2 sensor, i was getting 20L/100 which was crazy... I changed it and back to 23 AVg with a 325i and occasional pulls