2000 GrandAm 2.4 lit 4 cyl poor mileage

[jayjp200]

Hello,
My 2000 Grand Am 2.4 liter seems to have poor mileage and very high pickup.

The mileage seems very bad...where shall I start....Plugs ...injectors...o2 sensors...Tranny oil.
I get approx 400kms from one tank and fuel prices are going back up again .

Please suggest.
Thanks.

[Airjer_]

How many liters are you adding after the 400 km?

When did you notice the drop (when the temp dropped, since mid summer, last week)?

Have you noticed an extended crank after a hot soak?

When was the last time you did a tune-up, changed the air filter/fuel filter, checked the air in the tires?

[jayjp200]

I recently got the car 2 months ago. I also have a 99 Grand AM which gives me 470 kms on one gas tank.

The 2000 grand Am give only 400kms on a 47 litres tank.
I have changed the air filter and the spark plugs. The oil change has been completed. I have got brand new tires installed last months.
Thanks.
Jay

[Airjer_]

The estimated fuel economy for highway is 23 mpg (sorry its easier for me to do miles). You are getting 20.6 that's a difference of 11%.

Low tire pressure and cold weather could account for some of that (off the top of my head 8 psi can account for 12% it might be less), something to check into especially since temps have dropped in the last month. A tire will lose approximately 1 psi for every 10 degrees the temp drops (again based on fahrenhieght, sorry)

New tires can also effect fuel economy. We just had a discussion about an Envoy that lost 17% of its economy after new tires. I assume you drive both cars the same so that's not a factor and I also assume that they have the same engine so that shouldn't be a factor also.

[3100]

-dirty air filter
-dirty injectors
-heavy carbon deposits on intake valves
-low tire pressure
-vacuum leaks
-bad etc sensor
-bad o2 sensor
-dragging brakes
-wider tires
-unnecessary load in trunk
-bad wheel alignment
-winter grade fuel vaporizes quicker
-incorrect oil viscosity
-misfires
-