Help Please!

1551 Views 13 Replies 13 Participants Last post by Gig4Fun, Sep 3, 2005

Baginoman

Discussion Starter · Aug 26, 2005

Ok HERES THE DEAL just got my car about a week ago....had about 63 miles when i got it, and now has about 480. Ok my mpg is 12.1. Im finding most of the GT owners around here getting at least 14 mpg. I was thinking it was my tires. I checked and their psi was about 30-32....:?: SO i went to my local gas station and pumped them up to about 40 infront and 39 in back. Is this good..or should i lower the psi alittle? Could that of been my MPG issue???? thankyou!!:wavey

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06GT4me

· #2 · Aug 26, 2005

psi on tires or is it octane

Baginoman,
PSI settings for the stock tires are printed on the sticker on the inside of the door... if you have stock 17" I think it's 32 all around... double check with the sticker.
Quick question:
What octane fuel are you running? - reason I ask is I saw a guy over at Edmunds forum who was running 93 octane (no aftermarket tune) and was getting like 10-12mpg. I told him to switch back to 87 and see what happens.
Quick comment:
My 06 owners manual say during first 1000 mile break in do not expect to get a good or constant MPG.

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ErieGT

· #3 · Aug 27, 2005

Remove some air, If you leave it at 40psi you will be replacing tires very quickly. To much air will wear the center of the tire and not enough air will wear the outsides of the tire, you need the proper amount of air to maintain your tires and stability. Read the side of the tire as stated by 06GT4me. If you're only getting 12mpg, I only have one suggestion: Let up on the gas.:winks

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Baginoman

Discussion Starter · #4 · Aug 27, 2005

yaaaa u guys were totaly right. It says 32 front 32 rear. I dunno why it says cold though..heyyyy i might be 16 with a GT but im not a crzy driver lol. Average speed...20 lol yeaaa sry
BUt i try not to baby it all the time:winks I jus try to be careful...ya no how it goes!:kooky:

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Stoenr

· #5 · Aug 27, 2005

Running 40 in the fronts shouldnt wear the center out. You would need more psi than that to make a difference. I have run 40 front 35 rear for the last 250,000 miles on my tbird and all 8 sets of tires including snow tires wore even all the way across.

I think someone else hit the nail on the head about what it says in the owners manual about the milage during break in period.

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Moses

· #6 · Aug 27, 2005

I saw a major improvement in MPG when it started coming up on 1000 miles. My advice would be: 1)run the octane the car is tuned for; 2) set the tire pressure to what it calls for; 3) Eliminate the possibility it isn't running right (is it idling ok? Pinging? Detonation? etc) 4) Don't alter your driving habits/style 5)check the MPG again around 1000 miles.

~MO

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Stoopy

· #7 · Aug 27, 2005

Well, first off, I'd advise on breaking it in without paying attention to gas mileage yet. The two are at odds with each other when this car is new. The engine, trans and driveline are "tight" and need to be run through the entire operating range as much as possible without maintaining a constant, gas-mileage-inducing speed - the owner's manual advises NOT holding a constant speed, but instead varying your speed at all times for the first 2,000 miles. That is really how you break everything in - and it's fun at first but can get tiresome always slowly accellerating or decelerating, but it is WORTH it for anyone who has done this and then owned a well-running car for many, many many miles. Gas mileage will suffer - but it will suffer anyway if the car is new and tight also, so go for it...run it hard for short breaks after it's been rolling and warmed up for a spell even...moving some extra fuel through the manifold, injectors and heads is a GOOD thing!

Second - I didn't notice if your car is a manual or automatic. My GT with manual trans has, so far, recorded an extended steady "high" MPG of 26.9 on a trip down a long, straight and relatively slow country highway where we were maintaining about 60 MPH or so behind other steady-speed traffic.

Most importantly, to get the most accurate indication in my opinion, be sure to reset the "Average MPG" on the computer at every fill-up, so you won't be looking at the collective average measured since the car was born. I also reset the trip odometer and average speed before pulling away from the pump.

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Adrenal

· #8 · Aug 27, 2005

Baginoman said:
yaaaa u guys were totaly right. It says 32 front 32 rear. I dunno why it says cold though..heyyyy i might be 16 with a GT but im not a crzy driver lol. Average speed...20 lol yeaaa sry
BUt i try not to baby it all the time:winks I jus try to be careful...ya no how it goes!:kooky:

Baginoman,

The factory psi settings are for cold tires. Tires will heat as you drive, especially
in the hot weather and will give false readings. Check your tires after your car
has been sitting a few hours and then again after running it for several miles and
you'll see what I mean. And always go with the factory recomentaions for even
tire ware, longer tire life, and better handling.

GTYUP V8

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texascanuck

· #9 · Sep 2, 2005

Ok now I am seeing this 12mpg thing too. I have an '05 GT convertible automatic. Bought it used at the 900 mile mark. I am now at the 4000mile mark. At first mpg was around 17-19 but now down to 12. I did not employ the variable acceleration deceleration methodology proposed. Is there anything I can do. My car is stock, other than a locking gas cap.

tc

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greatgro

· #10 · Sep 2, 2005

Moses said:
I saw a major improvement in MPG when it started coming up on 1000 miles. My advice would be: 1)run the octane the car is tuned for; 2) set the tire pressure to what it calls for; 3) Eliminate the possibility it isn't running right (is it idling ok? Pinging? Detonation? etc) 4) Don't alter your driving habits/style 5)check the MPG again around 1000 miles.
~MO

Moses is right. My mileage REALLY sucked until 1000-1500 miles. I average 12 for a whole bunch of tanks of gas. Then all of a sudden I hit 14 and a few tankfuls after that I hit 15 and then the 16's were I've plateaued at 5k+ miles. I do 80%+ city driving.

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Dea. R&E

· #11 · Sep 2, 2005

My book says Regular gas. Is there a reason for premium?

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Otto Man

· #12 · Sep 3, 2005

Nope!
No to premium unless you want to fatten Exxon's wallet.
I'm getting 24 mpg after 5000 miles highway(GT). You guys gotta get your foot out of it.
Remember it's a 305 cu in V8. It's gonna suck gas given the chance (big foot).
Slow down, no unnecessary launches, 65 etc....
Save the gas for the big one!

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lthompson05

· #13 · Sep 3, 2005

16 years old with a new Mustang GT.... let me say I envy you...

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Gig4Fun

· #14 · Sep 3, 2005

last two weeks been getting 24.5 to 25 driving very nicely back / forth to work on the highway with only one stop sign. (at the end of my street!). Checked with a calculator and at the pump not the trip thingy. I am runnig the premium Diablo tune but fill with 89 octane. Now I benefit from the added spark advance and fuel curves but I don't floor it since there's a gas crisis. With dual knock sensors (and my good "sense") I will not damage the engine from pre-ignition. i haver built many engine and have 3 supercharged cars so no fear of damage here. NOTE:You will get the best utility from the lowest octane fuel too. Only use High Octane if you have too as it retards combustion.

BTW is is 281 cubic inches... not 305.

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