bad gas mileage

mscribellito · December 27th, 2007, 11:00 PM

so ive been getting terrible gas mileage since october now. i dont know the exact mileage because my odometer gear broke and i havent replaced it yet. but its pretty bad. it seems to have gotten bad when i took the intake manifold off. but it is bolted down tight with a new gasked so i dont believe it is that. i replaced the throttle body gasket as well.

i change my oil regularly
recently changed tranny fluid
replaced fuel and air filter
cleaned maf wires
cleaned iac
my o2 sensors are good
i have mil eliminators
tire pressure is good
fuel pressure is withing range
and i ran some fuel injector cleaner
plugs and wires were replaced last year

i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input
ive replaced the dpfe sensor and the valve was replaced a year ago as well as the evr. i dont think that would be causing the decrease in mileage because i had the egr problems before and it didnt seem to affect mileage.

im really stumped and have no clue what else it could be

Trance · December 27th, 2007, 11:04 PM

has it been cold lately in your area?

i often see a hit in milage when the temps drop to near freezing.

mscribellito · December 27th, 2007, 11:12 PM

i live in south carolina so it doesnt get too too cold here.
this is hard to explain but when im driving the car i cant really see the guage drop that much. its when i start it up next time i see that it went down considerably. idk if that makes any sense.

mmvi · December 27th, 2007, 11:43 PM

intake manifold wouldn't have anything to do with it as far as I know... if it did, there'd be a vacuum leak, and you'd be dumping fuel into the exhaust. plus, your brakes wouldn't work as well as they usually do if it was a vac leak.

i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input? -I don't understand that...

why'd you take the intake manifold off?

mscribellito · December 27th, 2007, 11:49 PM

Originally Posted by mmvi

i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input? -I don't understand that...

cel is on and thats the code that comes up

Originally Posted by mmvi

why'd you take the intake manifold off?

replace valve covers

PowerShiftz02GT · December 27th, 2007, 11:52 PM

Possibly need a new fuel Filter. Just a guess though. You usally change them around 50000-60000 miles

SSStang · December 28th, 2007, 12:49 AM

Originally Posted by mmvi

intake manifold wouldn't have anything to do with it as far as I know... if it did, there'd be a vacuum leak, and you'd be dumping fuel into the exhaust. plus, your brakes wouldn't work as well as they usually do if it was a vac leak.

i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input? -I don't understand that...

why'd you take the intake manifold off?

Depending on the leak you wouldn't notice it -
Any leak past that and you would notice your car sounding like it was cammed.

mustangjeff1997 · December 28th, 2007, 01:34 AM

yea, i noticed that my fuel guage likes to lie to me like that a lot too...it drives me insane because sometimes i'll pull into the garage with 1/4 tank and i'll leave the next morning with 1/8. it's a freakin' nazi, lol

El_Cangri · December 28th, 2007, 02:38 AM

are you sure your really getting bad mpg?

you should get your odometer fix and check your mpg who know if its ur fuel gauge going bad

and even I dont understand that code lol

mmvi · December 28th, 2007, 07:45 AM

Try this -explains the problem and how to fix it

December 27th, 2007, 11:00 PM	#1
mscribellito Newbie 1995 V6 Mustang Join Date: Oct 2007 Location: Gilbert, South Carolina Posts: 41	bad gas mileage so ive been getting terrible gas mileage since october now. i dont know the exact mileage because my odometer gear broke and i havent replaced it yet. but its pretty bad. it seems to have gotten bad when i took the intake manifold off. but it is bolted down tight with a new gasked so i dont believe it is that. i replaced the throttle body gasket as well. i change my oil regularly recently changed tranny fluid replaced fuel and air filter cleaned maf wires cleaned iac my o2 sensors are good i have mil eliminators tire pressure is good fuel pressure is withing range and i ran some fuel injector cleaner plugs and wires were replaced last year i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input ive replaced the dpfe sensor and the valve was replaced a year ago as well as the evr. i dont think that would be causing the decrease in mileage because i had the egr problems before and it didnt seem to affect mileage. im really stumped and have no clue what else it could be __________________ Rebuilt engine and transmission as of 2007 \| MAC 2.5" Off Road H-pipe \| MAC 2.5" True Dual Exhaust with Flowpath mufflers and turndowns\| MAC Cold Air Intake Last edited by mscribellito : December 27th, 2007 at 11:03 PM.

December 27th, 2007, 11:04 PM	#2
Trance Regular 2004 mustang 14.8 Join Date: Sep 2007 Location: Fort Hood, TX Posts: 139	has it been cold lately in your area? i often see a hit in milage when the temps drop to near freezing. __________________

December 27th, 2007, 11:12 PM	#3
mscribellito Newbie 1995 V6 Mustang Join Date: Oct 2007 Location: Gilbert, South Carolina Posts: 41	i live in south carolina so it doesnt get too too cold here. this is hard to explain but when im driving the car i cant really see the guage drop that much. its when i start it up next time i see that it went down considerably. idk if that makes any sense. __________________ Rebuilt engine and transmission as of 2007 \| MAC 2.5" Off Road H-pipe \| MAC 2.5" True Dual Exhaust with Flowpath mufflers and turndowns\| MAC Cold Air Intake

December 27th, 2007, 11:52 PM	#6
PowerShiftz02GT Enthusiast 2002 Mustang GT Join Date: Nov 2007 Location: Michigan Posts: 952	Possibly need a new fuel Filter. Just a guess though. You usally change them around 50000-60000 miles __________________ 5-Speed BBK 70MM Throttle Body Trick Flow Plenum BBK CAI Pulleys Yokohama Performance tires Flowtech Afterburner Mufflers Mac O/R H Pipe

December 28th, 2007, 07:45 AM	#10
mmvi Enthusiast Mustang Join Date: Jan 2007 Location: Pennsylvania Posts: 620	Try this -explains the problem and how to fix it Last edited by mmvi : December 28th, 2007 at 07:49 AM.

December 27th, 2007, 11:43 PM	#4
mmvi Enthusiast Mustang Join Date: Jan 2007 Location: Pennsylvania Posts: 620	intake manifold wouldn't have anything to do with it as far as I know... if it did, there'd be a vacuum leak, and you'd be dumping fuel into the exhaust. plus, your brakes wouldn't work as well as they usually do if it was a vac leak. i keep on pulling P1401 Differential Press Feedback EGR Circuit High Input? -I don't understand that... why'd you take the intake manifold off?

December 28th, 2007, 01:34 AM	#8
mustangjeff1997 Regular 2002 Subaru Impreza 2.5RS 5.26@942.19 Join Date: Dec 2007 Location: Under your bed Posts: 369	yea, i noticed that my fuel guage likes to lie to me like that a lot too...it drives me insane because sometimes i'll pull into the garage with 1/4 tank and i'll leave the next morning with 1/8. it's a freakin' nazi, lol

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