Gas mileage on 4.6 Mustangs - Ford Mustang Forum
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post #1 of 189 (permalink) Old 10-18-2009 Thread Starter
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Gas mileage on 4.6 Mustangs

i have a 1998 mustang gt with a automatic and it gets bad gas mileage. i know these things arn't supposed to get good gas mileage but i think it's below normal. it hasn't been full in a couple of months now but close to full. yesterday i cranked it up and washed it and dryed it and the gas gauge said 1/2 tank exactly then i cut it off for about 4 hours and then cranked back up and it started idling up to 2 thousand rpm as soon as i cranked it. ( the iac valve sensor needs cleaning or replacing like a lot of other mustangs on here the rpm needle is slow or hangs up). so i unplugged the iac sensor and blowed it off with my mouth and tapped it with a screwdriver and cranked it back up and the gas gauge said a little more than 3/4 full but less than half full. so i think i may have some fuel problems maybe a leak in one of the lines or fuel filter or something. ANY HELP OR IDEAS WOULD BE GOOD. THANKS.

ALSO IT USES REGULAR 87 OCTANE AND IT'S STOCK EVERYTHING BUT IT HAS NO MUFFLERS. AND MONTH AND HALF AGO I SEAFOAMED IT AND CLEANED THE MAF SENSOR WITH CRC MAF SENSOR CLEANER.


1998 mustang gt automatic stock
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Well rather than relying on the guage, try filling the tank and resetting the trip odometer, drive for awhile then refill the tank to full and calculate the milage (miles/gallons=mpg), you should get about 18/20 mpg in normal driving...from there you can know if you really have a consumption problem or a guage problem, at this point you are dealing with pure speculation.

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it has nothing to do with you signature, right? heavy feet=bad mileage.... the last part of your post was confusing for me, are you saying that the gas gauge will read different every time you crank it up? if you can just replace the IAC, its much easier than having to keep pissing with the old one

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post #4 of 189 (permalink) Old 10-19-2009 Thread Starter
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i suck at math so i probably won't be doing any calculating, but i will start doing the trip meter thing. nah it don't have anything to do with my signature i just made that up cause i thought it was cool. i drive at the speed limit (55) and below all the time plus even though im 21 iv'e only had my license since august 5 2009, so i haven't been driving that much. no it doesn't do that every time i crank it up just that one time i guess.

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post #5 of 189 (permalink) Old 10-19-2009 Thread Starter
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and we got this car almost a year ago in at the end of october 2008. my dad got disability check and i got a check from the money he made while he was working so it's really his car even though the check was in my name it's from where he was working. it's not really my car but i drive most of the time because he's to big for it. so i drive it safe and at or below the speed limit at all times.

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well you MUST calculate it, YOU dont need to do the math lmao thats what they made calculators for?? lol and if u have a cell phone, u prolly have a calculator... so like he said just do the number on the dash say like 150 miles then hit the divide key LMAO just teasin btw, then type in whatever the gas pump says exactly for numbers like 8.652Gal and hit = then it will give you, in this exact case, 17.337032 miles per gallon... so just round to the nearest solid (whole) number...in this case that would be 17.... do the calculation, and find out EXACTLY what ur MPG is... i did this just hte other day and got 30mpg!! so anywhere from 20-30 should be about accurate if its running right...

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What's your gas mileage?

I've been seeing a lot of threads about gas mileage here lately, so I decided I'd figure mine out, since I haven't done it for an average week with average driving.

I got 240 miles out of the tank, and filled up and took 13.2 gallons. So my gas mileage averaged 18mpg, and that was my standard driving. Mostly suburban stop and go, with a mix of 45 to 55 mph roads.

18.18 mpg with 4.10 gears....... Not too shabby.

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lowest I have had was 21.1 MPG. Highest was 23.2 MPG. Most of the time I get 22MPG. 25% stop and go, 75% 35-50 MPH. No freeway driving. I am curious to see what I get doing 70 MPH for a tank.

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When I first bought my car, I drove it like a pansy and could get just under 300 miles to a tank if I was careful. Car was stock.
Now I can't keep out of the throttle, and gas goes pretty quickly. I haven't even bothered to calculate fuel mileage. It would probably scare me as much as it would frighten me to add up the cost of all the mods I've done since last summer.
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I don't do much pure highway/city driving. Mostly back roads with a little of city and highway. I usually average between 16-18mpg. Not bad for a blower.

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Quote:
Originally Posted by sillyrabbit0420 View Post
When I first bought my car, I drove it like a pansy and could get just under 300 miles to a tank if I was careful. Car was stock.
Now I can't keep out of the throttle, and gas goes pretty quickly. I haven't even bothered to calculate fuel mileage. It would probably scare me as much as it would frighten me to add up the cost of all the mods I've done since last summer.
Same situation here, when my car was stock or stockish I babied her, now its too hard not to stomp on the gas haha. But I average around 14mpg with mixed city/highway driving.

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dash says 13mpg and its mostly stock... god im gonna hate to see what it will be in a few years after some mods lol

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Mods in signature, I'm getting 17mpg city, 18.5 mpg regular driving same situation as you bullitt, and 27.9mpg strictly highway.

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So, I guess 4.10's don't hurt your mileage as much as everyone thinks, huh?

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Quote:
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So, I guess 4.10's don't hurt your mileage as much as everyone thinks, huh?
Not at all, unless you do a lot of highway 65mph+ I guess. Have you gotten to do a straight highway run to see how you can do? And what are your RPM's at 65mph? Still debating which gears I want to go with and I do a lot of 55-65mph in my daily commute.


03 Mach 1: New toy
00 Kenne Bell GT vert: Sold
04 Sonic Blue GT: Missed
96 GT: First. Sold.

06 F250 6.0L 4x4: Studded, EGR delete, IDP tunes, 5" Straight pipe, S&B CAI
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