Bad mpg on 04 lancer ls

[liquidzorch]

Hello. I am getting really bad mpg on my 2004 lancer LS. It has no mods, everything is stock, running good and has had good maintenance.

I get around 8-9 L/KM Which is 18-21MPG. I never hit the throttle hard, normally 1/4 to 1/3 way down. Not going above 60mph. Normally drive with a/c on, but the best I have gotten with a/c off is 21mpg.

I refill tank once a week, I check how many liters it take to refill what I have used that week. Lately has been 8.4 km/l.

The check engine is on, but it is only from a bad front catalytic converter. This should not affect mpg in any way.

I have read stock lancer ecu's run rich. Any way to remap or something to run better mpg? Or anything I could try?

[Fat Charlie]

Tell us more about the car and your driving conditions, and what you used to get. An AT Lancer is rated 20 or 22 City- you're not all that far off.

[liquidzorch]

Originally Posted by Fat Charlie

Tell us more about the car and your driving conditions, and what you used to get. An AT Lancer is rated 20 or 22 City- you're not all that far off.

It is a 2.0l 2004 lancer ls. Automatic. City driving, but not much stop and go. I use mostly roads that are 80 km/h and have no traffic lights (or stops). And not much traffic. I just bought the car not to long ago. I had read people getting around 28mpg city, maybe they are exaggerating, but thats why I think it is no doing so good.

[user removed]

Whatever trashed the cat is probably the main issue.

regards
mech

[liquidzorch]

Originally Posted by Old Mechanic

Whatever trashed the cat is probably the main issue.

regards
mech

Hello. From what I have read the cat normally fail prematurely on this model. I havent read of a specific cause.

[liquidzorch]

What tests could I do in order to find out what caused the cat to fail? I hace a scanner and have rebuilt engines, so I know my way around. And have most tools needed.

[Fat Charlie]

More than one particular thing failing and taking out the cat, it could just be 11 years catching up with it.

[niky]

Fix the cat.

Beyond that, if it's the 04 2.0, that's the emissions strangled 4G63, which was on its last legs, by then... down to about 135 hp due to emissions... mated to an INVECS box with incredibly long legs. That's the only 2.0 auto sedan I've ever driven that felt like it was lugging in first gear! While a long final drive is good for highway cruising, it might be hurting you in traffic, where you'll feel the need to depress the gas a little more.

Beyond that, 8.4 km/l should be about average for that combo in light city driving... typically, those cars get 6 km/l or less in rush hour traffic here.

[jcp123]

Long shot, but if it uses a wideband O2 sensor to monitor the cats, that can affect fuel economy, it gives more precise information to the computer. If it detects a bad cat, programming will dictate that the proper correction will always be to miniseries emissions, that is priority over fuel economy or any other consideration. I say it's a long shot because widebands are rare even now, and I doubt anyone was using them on a C-segment car in '04, but food for thought.

As for the cat itself, if it's an exhaust manifold-mounted front cat, those are notorious for short life, they are exposed to the hottest exhaust gases.