Help: extremely poor gas mileage

Werewolf · #1 08-27-2007, 01:01 PM

Hi all

I own a 2001 3.0i with a manual tranny. Recently, last week or so, I've been experiencing extremely poor gas mileage (8 in city and 15 on freeway or less). My driving style is no different than before nor are the distances or types of driving.

When I drive for short trips (5 miles or less), I notice the gas gauge drop visually. Even 20-30 mile trips are taking 1/8 to 1/16th of the tank. None of the engine lights have come on. I have checked for fuel leaks and vapor smell and can detect nothing.

The only thing I can think of is I changed the oil on the x5 and did not reset the maintenance interval so I am on orange-red (instead of the green bars). Would this effect mileage? (i.e. adjust fuel-air mix?)

Thanks in advance

HPIA4v2 · #2 08-27-2007, 02:15 PM

Is this just happens overnight or more gradual?
I'll check tire pressure, condition(bald tires slippage) and then check air--filter, spark plugs.
Maybe wheel bearings are shot, can't see why since you don't live in snowy area( they salt the road 3-4 months like in East coast for example).
Good luck.

R8DX5 · #3 08-27-2007, 02:24 PM

8mpg???? damn, are you driving with your e-brake engaged???

UncleBob · #4 08-27-2007, 03:48 PM

how many miles on it?

when was the last time you changed the spark plugs?

one thing i can think of is a vacuum leak.

Werewolf · #5 08-27-2007, 04:10 PM

About 78K

I changed spark plugs as part of the Level II inspection at 60K.

Any guidance as to how to check for a vaccum leak?

Thanks

UncleBob · #6 08-28-2007, 03:02 AM

Quote:

Originally Posted by Werewolf

Any guidance as to how to check for a vaccum leak?

it's tough to give guidance in writing. you need to check visually for cracks, loose pieces, etc. on the intake side. sometimes you can hear whistling. i think there are devices that make a little "smoke" that you can see getting sucked in if there's a leak.

Aimster · #7 08-27-2007, 04:14 PM

Check your air filter.

utahx5 · #8 08-28-2007, 10:39 AM

Have you checked you're mass air flow sensor clean it (common and really common if you have a k&n filter or oil type) most shops have a smoke machine for checking evap emissions systems the fing vaccume leaks really quick we pump smoke into the intake any leak and out she blows leak found I don't belive that will be giving you that bad of mileage though

Werewolf · #9 08-28-2007, 01:10 PM

Hi all

After examining the intake system, there is a small but visible crack in the intake boot (elbow hose that feeds into the engine from the air intake)

Is this a DIY?

Thanks

GiRARDsays · #10 08-28-2007, 02:06 PM

Quote:

Originally Posted by Werewolf

Hi all

After examining the intake system, there is a small but visible crack in the intake boot (elbow hose that feeds into the engine from the air intake)

Is this a DIY?

Thanks

You can use some duct tape to seal it up as a quick fix for now. I would probably get a new unit though in the near future. I'm not sure if that is the culprit of your bad gas mileage though.