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Discussion Starter #1
I have a 2012 Eclipse with the 2.4 L SOHC engine and its been running through more gas than it should.

I've replaced the Spark Plugs, Ignition coils, all 4 O2 sensors. It also has a new air filter, and the oil is clean.

The Catalytic converters got clogged and the car dealership i bought it from was supposed to replace the catalytic converters but reamed them out instead.

Any ideas on why its burning more gas than it should? My gas mileage was better with the old O2 Sensors... the reason they were replaced was because i was getting a check engine due to all O2 sensors having NO ACTIVITY DETECTED.
 

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I have a 2012 Eclipse with the 2.4 L SOHC engine and its been running through more gas than it should.

I've replaced the Spark Plugs, Ignition coils, all 4 O2 sensors. It also has a new air filter, and the oil is clean.

The Catalytic converters got clogged and the car dealership i bought it from was supposed to replace the catalytic converters but reamed them out instead.

Any ideas on why its burning more gas than it should? My gas mileage was better with the old O2 Sensors... the reason they were replaced was because i was getting a check engine due to all O2 sensors having NO ACTIVITY DETECTED.
Did you use Denso O2’s and NGK Laser Iridium plugs?
 

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2009 GS Turbo. 2006+2007 GT
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I don't trust that the cat was cleaned to be as good as a new one. Reason being, they degrade over time, and actually fuse to themselves. Is the car also down on power from where it should be?

A clogged cat overheats, an overheated cat melts.
 

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Discussion Starter #6
I don't trust that the cat was cleaned to be as good as a new one. Reason being, they degrade over time, and actually fuse to themselves. Is the car also down on power from where it should be?

A clogged cat overheats, an overheated cat melts.

The shop HOLLOWED them out, and put anti foulers on the downstream O2 Sensors.
 

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2009 GS Turbo. 2006+2007 GT
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Oh, gutted cats flow like crap anyway. You could have bought new ones for the scrap value of the old OEM ones. Not 15mpg bad though.

What have you tested so far, aside from just changing parts? How are your fuel trims? Any vacuum leak testing?

NA I used to do 32mpg with a tune (unsure before that). Stock is rated higher than 15 for sure though.
 

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Oh, gutted cats flow like crap anyway. You could have bought new ones for the scrap value of the old OEM ones. Not 15mpg bad though.

What have you tested so far, aside from just changing parts? How are your fuel trims? Any vacuum leak testing?

NA I used to do 32mpg with a tune (unsure before that). Stock is rated higher than 15 for sure though.
I get 26MPG and u know my setup, that’s with highway/cruising/and spirited driving combined

that was on 5w20 tho

just changed my oil yesterday with 5w30 Pennzoil Ultra Platinum and Fran Ultra XG9688

did my WRX today with Rotella T6
 

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I get about 15mpg in my V6.
I get 26MPG and u know my setup, that’s with highway/cruising/and spirited driving combined

that was on 5w20 tho

just changed my oil yesterday with 5w30 Pennzoil Ultra Platinum and Fran Ultra XG9688

did my WRX today with Rotella T6
Id love to get 20+ mpg...
 

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So 6mpg different between header and gutted. That's huge lol.

I don't think that's why his is so bad, but it's a part. There's got to be something else wrong though, unless it's his right foot.
Yeah I agree, city driving and constantly revving and driving the shit out of it can definitely get you below 20 mpg especially without a tune and with header cats

My 26 mpg average was mainly 55 mph country road cruising, with an occasional rev out to redline in 2nd gear or so lol
 

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Discussion Starter #13
Short term fuel trims bank 1 and 2 fluctuate between -3.3% and 2.5%

Long term bank 1 sits at 3.5%
Long term bank 2 sits at 7.3%

Fuel pressure sits at 47 psi +/- 1 psi

I have NOT checked the throttle body yet, and the injectors spray like they should.
 

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Short term fuel trims bank 1 and 2 fluctuate between -3.3% and 2.5%

Long term bank 1 sits at 3.5%
Long term bank 2 sits at 7.3%

Fuel pressure sits at 47 psi +/- 1 psi

I have NOT checked the throttle body yet, and the injectors spray like they should.
That seems pretty good to me

How r u calculating your MPG?
 

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Discussion Starter #15
I use Trip A on the ODO and reset it before i pull away from the pump. I take the mileage on trip A and Divide it by the number of gallons i put in, at EVERY fill up.
 

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I use Trip A on the ODO and reset it before i pull away from the pump. I take the mileage on trip A and Divide it by the number of gallons i put in, at EVERY fill up.
That’s the way I do it too
Do you drive the car hard? City miles?
 
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