Gas mileage drop

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Bajahorse24
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Gas mileage drop

Post by Bajahorse24 »

I got back from deployment a couple months ago, it was driven while I was gone, so it did not sit. Before I was getting 25-27 MPG, with all the stuff that was on it when I got it. After I returned I have been getting 22-23, now some would not care but I drive 100 miles to work each day(50 each way). I did an tune up, NGK plugs and wires, stock air filter. I keep up with oil changes and tires. Right now the car has a oil leak, pretty sure it's the oil pan gasket. And throwing the P0442 Evap code, trying to figure that one out...

2003 with 150,000.

Any ideas??

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Last edited by Bajahorse24 on Tue Dec 06, 2016 5:53 pm, edited 1 time in total.
w.rohr
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Re: Gas mileage drop

Post by w.rohr »

Check your coolant level, I bet you are loosing coolant because of a failing head gasket. coolant gets in messes up all the sensors and you end up with poor mileage.
Bajahorse24
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Re: RE: Re: Gas mileage drop

Post by Bajahorse24 »

w.rohr wrote:Check your coolant level, I bet you are loosing coolant because of a failing head gasket. coolant gets in messes up all the sensors and you end up with poor mileage.
Coolant was fine, and have not had any watery oil. Thanks for the response

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Outlawed
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Re: Gas mileage drop

Post by Outlawed »

Another poster on here mentioned the IAC (Idle Air Control) sensor causing idling/sputtering/possibly drop in fuel mileage. I just cleaned mine. It was simple and now mine idles better. It only has 57K miles on it. For the price to clean it (go cheap early), you can't go wrong. See the youtube link below. If that don't work, check the 02 sensor. Now that can definitely cause it. However, (there's always an however) not so cheap a fix.

https://www.youtube.com/watch?v=cvE0L9g4PbQ
Bajahorse24
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Re: RE: Re: Gas mileage drop

Post by Bajahorse24 »

Outlawed wrote:Another poster on here mentioned the IAC (Idle Air Control) sensor causing idling/sputtering/possibly drop in fuel mileage. I just cleaned mine. It was simple and now mine idles better. It only has 57K miles on it. For the price to clean it (go cheap early), you can't go wrong. See the youtube link below. If that don't work, check the 02 sensor. Now that can definitely cause it. However, (there's always an however) not so cheap a fix.

https://www.youtube.com/watch?v=cvE0L9g4PbQ
I cleaned that about a month ago, I was having idling issues, took the whole throttle body apart, seems the butterfly plate could not close all the way due to carbon build up. Idles fine now lol.... After talking to a family member, it's down to the O2 sensor or MAP. I was told the O2 would throw a code first.. And the MAP would only after it is completely dead, sucks because that's more expensive... Guess it's time for some troubleshooting..

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Bajahorse24
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Re: Gas mileage drop

Post by Bajahorse24 »

Good video too thanks for that

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Outlawed
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Re: Gas mileage drop

Post by Outlawed »

OK, let us know what you find. :wink:
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kamesama980
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Re: Gas mileage drop

Post by kamesama980 »

MAJOR thing you didn't mention: where are you?
cold weather = crap MPG
winter mix gas = crap MPG

Who drove it? how do they drive? did they maintain it? How did they drive it? just short trips once in a while or normal driving including highway?
Tire pressures? dragging brakes? bad bearing? missing/torn under tray or bumper? One of the problems with "poor mileage" complaints is there are so many factors.

P0442 is small leak detected in the EVAP system. Won't directly affect mileage but could be related to whatever is causing it.

The O2 sensor has a test that the PCM runs before it throws a code. The vehicle has to meet certain conditions before the test runs. It's possible (though rare) to go years without running the emissions readiness tests and thus never throw a whole slew of codes. Even then, it's possible (again rare) for the sensor to drift without "failing" the test.

MAP sensor is critical for engine operation (on the 03 NA). If it failed, the car wouldn't be drivable. It is continuously monitored (unlike the O2s) so you'd get a code immediately.
-Russell
"You don't get to judge me for how I fix what you break"
03 sport 5mt
05 turbo 5mt vf39 and other STI bits, 3" turbo-back
Bajahorse24
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Re: RE: Re: Gas mileage drop

Post by Bajahorse24 »

kamesama980 wrote:MAJOR thing you didn't mention: where are you?
cold weather = crap MPG
winter mix gas = crap MPG

Who drove it? how do they drive? did they maintain it? How did they drive it? just short trips once in a while or normal driving including highway?
Tire pressures? dragging brakes? bad bearing? missing/torn under tray or bumper? One of the problems with "poor mileage" complaints is there are so many factors.

P0442 is small leak detected in the EVAP system. Won't directly affect mileage but could be related to whatever is causing it.

The O2 sensor has a test that the PCM runs before it throws a code. The vehicle has to meet certain conditions before the test runs. It's possible (though rare) to go years without running the emissions readiness tests and thus never throw a whole slew of codes. Even then, it's possible (again rare) for the sensor to drift without "failing" the test.

MAP sensor is critical for engine operation (on the 03 NA). If it failed, the car wouldn't be drivable. It is continuously monitored (unlike the O2s) so you'd get a code immediately.
I am in VA, and this issue was from summer till now, in laws drove it, and they don't dog it or anything, just trips once and a while to keep it running. I always keep up with the tires, brakes are new, and the rubbed a little when we put them on over a years ago, due to the parts on the hub being so worn. The tray underneath is in good condition, never thought of that. That I know, the bearings are good (doing just the grab the tire test). I figured those 2 things would have codes associated with them.

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Bajahorse24
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Re: RE: Re: Gas mileage drop

Post by Bajahorse24 »

kamesama980 wrote:MAJOR thing you didn't mention: where are you?
cold weather = crap MPG
winter mix gas = crap MPG

Who drove it? how do they drive? did they maintain it? How did they drive it? just short trips once in a while or normal driving including highway?
Tire pressures? dragging brakes? bad bearing? missing/torn under tray or bumper? One of the problems with "poor mileage" complaints is there are so many factors.

P0442 is small leak detected in the EVAP system. Won't directly affect mileage but could be related to whatever is causing it.

The O2 sensor has a test that the PCM runs before it throws a code. The vehicle has to meet certain conditions before the test runs. It's possible (though rare) to go years without running the emissions readiness tests and thus never throw a whole slew of codes. Even then, it's possible (again rare) for the sensor to drift without "failing" the test.

MAP sensor is critical for engine operation (on the 03 NA). If it failed, the car wouldn't be drivable. It is continuously monitored (unlike the O2s) so you'd get a code immediately.
I am in VA, and this issue was from summer till now, in laws drove it, and they don't dog it or anything, just trips once and a while to keep it running. I always keep up with the tires, brakes are new, and the rubbed a little when we put them on over a years ago, due to the parts on the hub being so worn. The tray underneath is in good condition, never thought of that. That I know, the bearings are good (doing just the grab the tire test). I figured those 2 things would have codes associated with them.

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Bajahorse24
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Re: Gas mileage drop

Post by Bajahorse24 »

So, was hearing some break noise. Pulled the wheel and the inner pad is worn all the way, just replaced a year ago, so think the caliper is shot. And also to add to the Mayhem, the Cv axel boot is torn... And the Hub nut is rusted to all hell and can't get a socket on it

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kamesama980
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Re: Gas mileage drop

Post by kamesama980 »

Bajahorse24 wrote: Wed Dec 28, 2016 4:38 pm So, was hearing some break noise. Pulled the wheel and the inner pad is worn all the way, just replaced a year ago, so think the caliper is shot. And also to add to the Mayhem, the Cv axel boot is torn... And the Hub nut is rusted to all hell and can't get a socket on it

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You aren't even to the good part yet. I bent the table on my harbor freight 20t press trying to get the LF axle out of the hub
(RF popped right out, no problem). Ended up turning 2/3 of the axle stub into drill shavings, tore open the ball joint (another oh-so-delightful adventure), and replaced the wheel bearing for good measure (between side-loading and the torch, I didn't feel it was the best idea to leave it in). If you google how to remove a stuck CV axle from the hub, it's a 200x legacy or outback LF axle (same suspension as ours). he takes it to a truck mechanic who maxes out a 50t name brand press then the guy gives up and gets parts from a junkyard.
-Russell
"You don't get to judge me for how I fix what you break"
03 sport 5mt
05 turbo 5mt vf39 and other STI bits, 3" turbo-back
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