Decreasing Gas Mileage???

[projectGTZ]

Well, I was getting about 320 miles to a tank of gas and the car is getting about 250 now. The car has 97K on it and is well maintained. I run 93 octane in it (because i want to :D). Checked the air filter, same shitty stock one. Checked right foot. Plugs, wires, rotors, and cap are fairly new. Injectors were cleaned at 60K tune up. Never messed with the o2 sensor(s?). Stock catalytic converter. I don't know. Let me hear some advice.

[monkeyman]

What kind of car do you have? Is it a galant? because if it is we dont have rotors and caps, its DIS. Also I4 or V6?

[WarmAndSCSI]

What kind of car do you have? Is it a galant? because if it is we dont have rotors and caps, its DIS. Also I4 or V6?

Please don't give advice if you don't know what you're talking about. The guy knew he had a cap and rotor because HE DOES. 6G72's in our cars have distributors :roll:

Any way, definitely could be your oxygen sensors if you've done everything else. If the upstream sensors are putting out false readings (or just 1), you may run slightly rich in closed loop and thus lose gas mileage. It will eventually pop a code.

[glantv699]

WarmAndSCSI has the advice you want. I have replaced 1 O2 sensor in the 3 1/2 years I've owned the car. Ever think of replacing the fuel cap? That's on my list of things to do, I was spitting out codes about the EVAP system.

[projectGTZ]

Thanks for the quick response. I was thinking o2 sensor as well. Hey monkeyman...........use the keyboard filter!!

[G-spot]

Hey monkeyman...........use the keyboard filter!!
:smt117

[Eclipse97526]

Damn, i got a I4, it gets about 375 to a tank on the freeway, sometimes around 230 - 250 a tank around town :( Grrr. o2 sensors 189.99 lol ! :P

[run1206]

Damn, i got a I4, it gets about 375 to a tank on the freeway, sometimes around 230 - 250 a tank around town :( Grrr. o2 sensors 189.99 lol ! :P
i bought mine for about 200 when i had to redo my senors, though i'm sure they may be sensors out there that are cheaper...

[9G]

it might be the weight of the driver thats slowing the car down making the engine work harder.

hmm? lol

plus, if its cold outside then you will lose gas mileage since the engine likes cold air.

more vroom vroom.

[run1206]

it might be the weight of the driver thats slowing the car down making the engine work harder.

hmm? lol

plus, if its cold outside then you will lose gas mileage since the engine likes cold air.

more vroom vroom.
i only weight 120, so that's no excuse :lol:

i've noticed the car does move faster recently since it's been cold. usually i wait to wait til night to feel more power :?

still, i'm dropping to about 280 to a tank, and i changed my o2 sensor last october, i wonder if there's another o2 sensor that has gone bad :smt017

[projectGTZ]

I don't know, could have something to do with the weather. I am in South Kentucky/Northern Tennessee and the weather has been crazy here. It has been in the 70's the past couple of days but it was freezing not to long ago.

Ouch, o2 sensors are that expensive?! The o2 sensor probably shares some of the blame for weak ass gas mileage.

[Galant306m]

its the gas. i had the same problem ware i thought somthing was wrong. but its because the US switch's gas, kinda they add more ethenol to our gas. Its the winter blend. your gas milage will go back up once we switch back to the other blend.

[run1206]

its the gas. i had the same problem ware i thought somthing was wrong. but its because the US switch's gas, kinda they add more ethenol to our gas. Its the winter blend. your gas milage will go back up once we switch back to the other blend.
:evil: damn gas companies :evil:
and i thought i had a problem with my o2 sensor or plugs :roll: :lol:

[WarmAndSCSI]

No, that's wrong. There's no way a small percentage of ethanol (10%-15%) could be causing that dramatic of a drop in gas mileage. The short term and long term fuel trims will richen the fuel mixture just a few percent when running a small percentage of ethanol, so you'll see maybe 5-10% worse gas mileage.

[run1206]

No, that's wrong. There's no way a small percentage of ethanol (10%-15%) could be causing that dramatic of a drop in gas mileage. The short term and long term fuel trims will richen the fuel mixture just a few percent when running a small percentage of ethanol, so you'll see maybe 5-10% worse gas mileage.
in either case, i'm still gonna double check all my components (plugs, o2 sensors, plug wires, weight, etc....) just to be on the safe side...

[projectGTZ]

My thoughts were that ethanol has a higher octane rating than gasoline. I know that 100% ethanol has a octane rating of 115.

[Galant306m]

you cant run on 100% ethenol! you would be putting pure corn oil into your tank. they raise the percent form 10 up to 15. Dont ask y its just what the refineries do. either way if you are running 87 89 or 91 your still getting the same percent of ethenol as the oter octain ratings. also it really isnt paying for you to run premium gas, our motors only have a 9:1 compression ratio, which is a little bit low to run that high of octane. just run 87 and every once in a while like when you do a oil change put in some premium. your gas milage will go back up in the spring when they go back to 10% ethenol.

[run1206]

My thoughts were that ethanol has a higher octane rating than gasoline. I know that 100% ethanol has a octane rating of 115.
:shock: jeez, pretty much race gas

[Galant306m]

just add some EverClear to your Gas! :lol:

[duh2150]

dam did i hear yall payed 200 for a sensor!?! i ned to buy me a bike and pedal around town lol, id take it out and make it think its running perfect all the time, i wonder if we can do that, insted of having one not have one at all :) the end of the problems

[run1206]

dam did i hear yall payed 200 for a sensor!?! i ned to buy me a bike and pedal around town lol, id take it out and make it think its running perfect all the time, i wonder if we can do that, insted of having one not have one at all :) the end of the problems
well... i took my car to a shop cuz i had a SES light on... and i think bank 1 sensor 2 was shorted (not sure if that the right one....). anyways, the mechanic got me a new one and charged me 200 for the part and 50 for labor. next time it happens, i'm doing it myself; i'm sure i can find a universal sensor for less than 200 out there, and just put it on myself.

[dknight3]

also it really isnt paying for you to run premium gas, our motors only have a 9:1 compression ratio, which is a little bit low to run that high of octane. just run 87 and every once in a while like when you do a oil change put in some premium. your gas milage will go back up in the spring when they go back to 10% ethenol.
i didnt realize they made v6 7g's, lol look at his fender in his sig.

[EVOlved]

damn, there was be sumthing seriously wrong with my car...i have a 4 banger 8g and am getting about 270 per tank. i drive fairly easy as i have the evo for the spirited driving. how much should i be getting per tank? i have seen numbers well over 300, what could cause such a major drop? i check my tire pressure weekly, air filter changed when needed, etc

[Ivory8g]

well... i took my car to a shop cuz i had a SES light on... and i think bank 1 sensor 2 was shorted (not sure if that the right one....). anyways, the mechanic got me a new one and charged me 200 for the part and 50 for labor. next time it happens, i'm doing it myself; i'm sure i can find a universal sensor for less than 200 out there, and just put it on myself.

LOL i got quoted $400 to change 2 o2 sensors about a year ago and i tell you what I changed one because only one was bad and they told me 2 were bad. took me 30 mins and $75.00 and I changed it all by myself. repair shops are a rip 98% of the time.

[99 galant]

you guys think theres something wrong with your cars? drive mine. i have to drive like grandma just to get 220. i need to replace alot of shit this coming sping

and the 220 is NOT just the winter for those of you that might comment that, its been that way since last april when i bought it but thought it was normal until i read this thread when it first was made

[spardavr4]

Geez 220? I get 240 and I occasionally drive it pretty hard. Yeah, I'd say it's the gas, my miles went down in the winter too.

[99 galant]

its not the gas for me. its my car

its been that way threw spring, summer, fall, and winter. no change. i have a shit load of money i need to drop into a tune up since i have no clue how to do the shit my self

[spardavr4]

Aw, c'mon, I think you could at least change the spark plugs yourself if yout gonna do a tune-up. I didn't know how to do that either but I learned!

[99 galant]

see my problem is this

wtf are spark plugs? anyone can laugh. but the more i try to learn about performance the more i confuse the shit outta my self. my mom knows a few things about cars, but not enough to help me and my dad, lets no go there. my cousin only works on american trucks like his ford. so i have to rely on making money to get the work done since i cant rely on anyone to help me, i cant get a ride to work if i screw it up

edit: im not asking symphy, or for people to spoon feed me. but i dont have 2 cars or another way to work or school. so i cant just try stuff to learn to hope it works

im a hands on learner and its hard to understand what is what about the engine when i read the good info on here. plus i hardly have any tools. it would be cheaper ot have someone else do it

[Rusty]

see my problem is this

wtf are spark plugs? anyone can laugh. but the more i try to learn about performance the more i confuse the shit outta my self. my mom knows a few things about cars, but not enough to help me and my dad, lets no go there. my cousin only works on american trucks like his ford. so i have to rely on making money to get the work done since i cant rely on anyone to help me, i cant get a ride to work if i screw it up

edit: im not asking symphy, or for people to spoon feed me. but i dont have 2 cars or another way to work or school. so i cant just try stuff to learn to hope it works

im a hands on learner and its hard to understand what is what about the engine when i read the good info on here. plus i hardly have any tools. it would be cheaper ot have someone else do it

buy a repair manual. it will be your best friend.

but to change plugs all you need is a 3/8" ratchet, 8" extension, a 5/8" spark plug socket, a 10mm socket and a 12" piece of 1/2" ID rubber hose. assuming you an I4, just take out the 4 bolts on the coil packs (unplug them first), pull the plugs wires loose from the plugs and wires, using the plug socket, remove the plugs. use the hose to keep from cross threading the plugs and just follow these steps backwards to install. oh and note how the wires run before you remove them

sry, that was off topic, but i couldnt help myself

[99 galant]

im V6, and i learned over the years from installing my moms dvd stuff with the vcr and my videogames to watch the wires, but thanks for reminding me. id prolly forget. you should see what my mom did to the wires for the dvd player :lol: has tags on them made of paper and tape, i do have a small set of sockets, nothing bit enough for what you explained tho

[Rastus]

I run 93 octane in it (because i want to :D).
If that's your car with a V6 in your sig, the manual says to run 93 octane(my V6-2001 book says so anyway). Just FYI, octane retards combustion to prevent high compression engines from pre-ignition, so higher octane gas develops less horspower than lower octane.