My Legacy has always gotten poor gas mileage and it was something that I was willing to deal with because the AWD and 2.5L engine is worth it. But as of a week ago its dropped from 20 MPG to 10 MPG! And at $1.80 for a gallon im gonna go broke.

 

Ive been driving it very gently without quick accelerations and I reinflated the tires. Anyone have any ideas or have expirienced the same problem?

Wow!

 

There has to be something wrong to get this bad. Do you have a check engine light on?

Air filter air filter air filter.. when was the last time it had a tune up?

Originally posted by Slegacy96

My Legacy has always gotten poor gas mileage and it was something that I was willing to deal with because the AWD and 2.5L engine is worth it. But as of a week ago its dropped from 20 MPG to 10 MPG! And at $1.80 for a gallon im gonna go broke.

 

Ive been driving it very gently without quick accelerations and I reinflated the tires. Anyone have any ideas or have expirienced the same problem?

 

What's the condition of the spark plugs? The air filter? The fuel filter?

 

Is the "Check Engine" light illuminated?

Actually it was just tuned up in December. And no, the check engine light isnt lit up.

Originally posted by Slegacy96

Actually it was just tuned up in December. And no, the check engine light isnt lit up.

 

So the plugs were brand new in December. What do they look like now? Are they loaded with carbon? Oil?

And, how do I get to them?

Originally posted by Slegacy96

And, how do I get to them?

 

For the driver's side, remove the battery and the washer reservoir. For the passenger's side, remove the intake duct work. It's not as bad as it looks. When you reinstall the plugs, tighten to 21 Newton-meters.

If a malfunctioning engine was the cause of a paltry TEN mpg, you wouldn't have to check the sparkplugs to find the problem.

Your engine would be shacking like an out-of-balance washing machine from one or more misfiring cylinders. You could probably smell raw, unburnt gas from the exhaust pipe. Your catalytic converter would be glowing like lit a charcoal briquet. First do a walk aroung the car, and look for leaks, and possibly a collapsed gas tank. Run another tankful and recheck your results. The engine could be the problem, but it would be pretty far down on my list.

If this is based on one tankful, I'd suspect someone siphoned some gas out for their 'donorcycle',car or lawnmower.

Originally posted by 1 Lucky Texan

If this is based on one tankful, I'd suspect someone siphoned some gas out for their 'donorcycle',car or lawnmower.

 

Or could be very bad gas. My mother-in-law got a tank full that was test out to be something like 42%. It was back on the east coast and one of these no-name places. She drove off and about 2 miles later her car died.

Coolent temp. sensor?

 

When mine went I had terrible gas mileage...it was like gas was being dumped into the engine. My CEL came on for that...is yours on?

any possibility the fuel gauge is bad and you aren't using as much gas as you think?

Yeah...when my gauge reads 1/4 tank I have around 1/2 a tank. Its tricky. :-/

My Gas Guage isnt very accurate. Ive calcualted my gas mileage after two tanks of gas. The first one was 10 MPG and then today it moved up to 12 MPG. No CEL light yet, but Ill keep looking. As for bad gas, my mom puts the same gas in her Lexus and it runs fine and always make sure to put in 89 octane. Any possibility this could be related to my transmission slipping?