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Discussion Starter · #1 ·
Hello,

I have a stock 2003 V6 (3.8L) Stang with 126K miles. I have had it exactly 1 yr this month. I have noticed my gas mileage going down from 200 miles per tank to about 180-ish. I changed the plugs, wires, clean the K&N air filter every 2 months with the recharge kit, changed the fuel filter about 10k miles ago along with throttle position sensor and IAC valve/sensor. I change those 2 things becuase she was throwing codes. I KEEP the oil changed religiously with the recommended 5w20 Castrol or Mobil1 (whichever has better deal at time). I use Lucas FI cleaner when I change my oil with a full tank of gas. I do use the cheap 87 gas cause I never noticed ANY differnce in performance or mileage with the 93 octane. I also keep my tires properly inflated.

(**I can give more details but didnt want to make this too long and bore people***)[/U]


In saying that I see others saying they get 275 to 300 miles per tank!!?? How the hell????


I also hear a slight exhaust leak or O-ring leak from exhaust coming from the middle of the car under the driver side where the exhaust is going back. I also have a lifter that taps on the drivers side until it gets warm and gets oil going through it.

1. What type of exaust system is good and decently priced to gain HP AND increase mileage? I heat good and bad about Flowmaster but they are pricey (unless that is what I really need??) Any good recommended websites to look at? And do I need to replace the stock headers all the way up to the engine too?

2. Is it recommedned to spend $400 on some type of tuner to gain HP AND mileage? DIABLO comes to mind but I dont know much about them or anyone who has installed on on a car like mine?? HELP

3. Is there another brand besides K&N for CAI that can get the same performance? I am trying to save $$

4. Any other recommendations?



I need to stay around $1,000 budget if possible cause I BE BROKE and do it myself (except the exaust since I dont have a welder or pipe bending tools). I also dont mind buying used somewhere if there are any suggestions or websites anyone can recommend???

PLEASE HELP. I need someone who knows of a good tuner (DIABLO or whatever) and is it worth $400 in a V6? It is paid for and I cant afford a GT so dont tell me to get a V8!!!! No car payments for me!!
 

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delete your bottom two cats and replace your upper cats with some highflow cats. better gas mileage as well as power to
 

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Discussion Starter · #3 ·
darn, how many cats are there? 4?

If there are 4, are you saying to only have 2 by the time I am finished? Besides for emissions, are cats really required? I have heard of ppl cutting them out completely and then welding a plate underneath to make the emissions ppl think there is one when they look with those mirrors. If I just take them out completely wouldnt that be LESS restrictive?
 

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a tuner is worth it and can carry over to other vehicles
also i'd recommend a 87 tune. if you really care about mpg, you can get a tune specifically to get the most mpg out of your fuel

what kind of exhaust are you looking to do? just a catback or full exhaust including or excluding headers

the leak could definitely be hurting your mpg

i think you're recharging your air filter to often? not sure don't have a k&n

if it makes you feel better i used to get 280 then 250, then 200, then 180, now like 200-250 per tank

your o2 sensors could be bad

you changed your spark plugs? what plugs did you use? and did you change your wires along with your plugs?

you could possibly increase your mpg if you do the 1/3, 1/3, 1/3 seafoam
 

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darn, how many cats are there? 4?

If there are 4, are you saying to only have 2 by the time I am finished? Besides for emissions, are cats really required? I have heard of ppl cutting them out completely and then welding a plate underneath to make the emissions ppl think there is one when they look with those mirrors. If I just take them out completely wouldnt that be LESS restrictive?
theres two cats, and two pre-cats, and not sure, but i don't see why it wouldn't, to pass emissions you'll need cats, atleast in va.
 

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My car has almost 150k miles on it (2002 v6 100% stock, bought it at 130k and don't know what kind of maintenance it had from previous owner, but have yet to change anything out) and I get about 275m a tank. When I'm heavy on the pedal I get like 220-250 though. Try driving more conservative and less pedal-happy.
 

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Is your car an automatic or manual? The added drivetrain loss of an auto combined with the different gear ratios in the transmissions makes them lose MPG.

A good tune will help with gas mileage if you drive right and will give you some more power if you want to play around.

The biggest thing for gas mileage is how you drive. Try to avoid having to come to a complete stop, figure out when your injectors shut off completely and take advantage of it, shift at the right RPMs and don't do stupid things like accelerate before a red light.

I can easily get 350-400+ miles out of a tank if I try.
 

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.I do use the cheap 87 gas cause I never noticed ANY differnce in performance or mileage with the 93 octane.

You will never see better performance from simply running a higher octane fuel unless you're having detonation problems. If you want to take advantage of the higher octane, you need to advance your timing which requires a handheld tuner.

1. What type of exaust system is good and decently priced to gain HP AND increase mileage? I heat good and bad about Flowmaster but they are pricey (unless that is what I really need??) Any good recommended websites to look at? And do I need to replace the stock headers all the way up to the engine too?

Exhaust does very, very little on our cars. We basically do it for the sound. One of the best and cheapest routes you can go is to have an h pipe custom fabbed at an exhaust shop and have them throw on 2 Flowmaster 40 or Thrushweld mufflers plus 2 exhaust tips of your choice. You can leave the stock headers if you want because shorty headers will offer no gains and burn a big hole in your pocket. The only headers worth going with are long tubes. But if you're looking for decently priced then long tubes are not for you. Expect $300+ for the headers and you'll need MIL eliminators because you won't be running rear cats anymore.

2. Is it recommedned to spend $400 on some type of tuner to gain HP AND mileage? DIABLO comes to mind but I dont know much about them or anyone who has installed on on a car like mine?? HELP

Tuners are great if you plan on really modding your car. If you're going to end up just doing a CAI and exhaust then call it good, it's not something I would recommend. However with it you will be able to take advantage of 93 octane fuel, turn off your rear O2 sensors (good for long tubes so you don't need MIL eliminators), remove your speed limiter, change your shift points/firmness, and it is needed for differential gear changes. Most of us around here use SCT tuners, but there are a few people with Diablo tuners.

3. Is there another brand besides K&N for CAI that can get the same performance? I am trying to save $$

Our stock intakes are one bend and a few inches from being CAIs themselves. Go to AmericanMuscle.com and pick up the $75 CAI they have. Works just as well as the K&N and it will save you a lot of money. But if you've got money to spend, you should look into a Windstar upper intake swap instead of a CAI (check VAPauto.com). A CAI will gain you maybe 5hp at the crank with a tune. Windstar upper intakes have been proven to give something like 8rwhp and 12ft/lbs of torque.

4. Any other recommendations?


Windstar upper intake, 3.73 or 4.10 gears, tlok, exhaust, cam, visual upgrades. That's just what I would do. You need to decide exactly what you want to do with your car. The turbo or supercharger route might be a good idea if you're looking at making a badass V6, but you're going to have to put some money into it.
Answers in quote.

Edit: Also, have a look at this link, might be some helpful stuff there: http://www.moddedmustangs.com/forums/v6-mustangs/79395-look-here-before-asking-about-mods.html
 

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I have Diablo sport predator and love it.
 

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Discussion Starter · #10 ·
a tuner is worth it and can carry over to other vehicles
also i'd recommend a 87 tune. if you really care about mpg, you can get a tune specifically to get the most mpg out of your fuel

What did this do for you: 1. as far as immediate power, 2. as far as mpg?? Any better? But also did you have other mods or was this one of the first things you did?

what kind of exhaust are you looking to do? just a catback or full exhaust including or excluding headers

I dont know much about exhaust and that is kinda why I was asking to see what everyone else was doing with their 3.8's. I may go around to some exhaust shops tomorrow and see what they recommend and would charge to do it (unless you guys have some good suggestions)

the leak could definitely be hurting your mpg

i think you're recharging your air filter to often? not sure don't have a k&n

if it makes you feel better i used to get 280 then 250, then 200, then 180, now like 200-250 per tank

your o2 sensors could be bad

you changed your spark plugs? what plugs did you use? and did you change your wires along with your plugs?

I used the standard Motorcraft plugs. I also bought new plug wires but dont recall the brand. It wasnt the Auto Zone special. I think I got them at O'Reilly Auto Parts and it was a higher end 8mm set of wires


you could possibly increase your mpg if you do the 1/3, 1/3, 1/3 seafoam
I am not sure how to do this or if there is a special way to do it??
 

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Discussion Starter · #11 ·
I have Diablo sport predator and love it.
So you have the 3.8 with a Diablo tuner? Was it stock before you bought this or did you have other mods? I ask because I am curious as to how well it works with everything else being stock and only having a tuner? Does yours have Standard, Performance, and Racing settings? Which do you typically keep it on?

Where did you get it? Or rephrase...where is a good place to get one 'cause I am seriously considering SOME TYPE of tuner. If you have a 3.8 and a Diablo and it did wonders for you then I may go that route :D
 

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mcqueen hit the nail on the head...honestly i don't know which question to go into detail first....understand now that 98% of mods that will increase will hurt your mpg in the long run...that could mean the mods themselves kill your mpg or your new lead foot you will most likely get from adding things
 

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Discussion Starter · #13 ·
Answers in quote.

Edit: Also, have a look at this link, might be some helpful stuff there: http://www.moddedmustangs.com/forums/v6-mustangs/79395-look-here-before-asking-about-mods.html
MCQueen, that is a bad ass thread about the Mods. Are you affiliated with the person that created that link? It says at the bottom to contact him as he has parts to make him an offer. I am curious as to what all he has (tuners, CAI's, etc...)

No, mine is an automatic.

I dont think the lifter that is tapping is going to cause an issue?? I dont want to take the valve cover off if I dont have to. ;)

Yea, I am looking to start with the cheap mods first and work my way up slowly to the bigger ticket items (bigger ticket = $450 or more)

What about bigger throttle body? I saw some 70mm (or maybe 73mm??) that were around $300 and had gains of 9rwhp and better gas mileage.

On the same website was a 1" spacer that goes under the throttle body to increase air flow in a vortex and had gains of 8rwhp ($89 bucks!!) and it was a quick bolt on.


So many options I just dont know what to do. That is why I am asking all of you guys!!!;)
 

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Discussion Starter · #14 ·
mcqueen hit the nail on the head...honestly i don't know which question to go into detail first....understand now that 98% of mods that will increase will hurt your mpg in the long run...that could mean the mods themselves kill your mpg or your new lead foot you will most likely get from adding things
Talk about hitting the nail on the head...LOL...I could hardly concentrate on your post without staring at that picture of the girl pulling her pants up (under your name)...dammit, now what were we talking about.....

uhhh yeah, I see what you are saying. Increase in HP will lower mpg. So you think maybe a custome tune?? Hell I am all confused now with which way to go.
 

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Discussion Starter · #15 ·
mcqueen hit the nail on the head...honestly i don't know which question to go into detail first....understand now that 98% of mods that will increase will hurt your mpg in the long run...that could mean the mods themselves kill your mpg or your new lead foot you will most likely get from adding things
I also see you live in Portland, TN. I live in Murfreesboro :)

Any idea what brand of tuners people are using in this neck of the woods>???
 

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Discussion Starter · #16 ·
Is your car an automatic or manual? The added drivetrain loss of an auto combined with the different gear ratios in the transmissions makes them lose MPG.

A good tune will help with gas mileage if you drive right and will give you some more power if you want to play around.

The biggest thing for gas mileage is how you drive. Try to avoid having to come to a complete stop, figure out when your injectors shut off completely and take advantage of it, shift at the right RPMs and don't do stupid things like accelerate before a red light.

I can easily get 350-400+ miles out of a tank if I try.
I see that your car is supercharged? How hard was that to do yourself? Does that help you with your mpg?
 

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I see that your car is supercharged? How hard was that to do yourself? Does that help you with your mpg?
It wasn't that hard. Took the better part of a day but it probably would have been faster if I didn't throw my back out the day before and take a bunch of Vicodin so I could do it. Or if I had someone else helping me at the time.

It didn't really do anything to my mpg. Speed limits in cities keep me from getting on it too much and most of my highway driving is out of boost with the standard 14.7 AFR.
 

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All these gas mileage threads make me feel like I'm on a Toyota forum.:dunno
 

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If your in the buro please check out TNmustangclub.org

it's a bit slow right now, however car show and track season aren't in full swing yet around here. :yes
 

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MCQueen, that is a bad ass thread about the Mods. Are you affiliated with the person that created that link? It says at the bottom to contact him as he has parts to make him an offer. I am curious as to what all he has (tuners, CAI's, etc...)

No, mine is an automatic.

I dont think the lifter that is tapping is going to cause an issue?? I dont want to take the valve cover off if I dont have to. ;)

Yea, I am looking to start with the cheap mods first and work my way up slowly to the bigger ticket items (bigger ticket = $450 or more)

What about bigger throttle body? I saw some 70mm (or maybe 73mm??) that were around $300 and had gains of 9rwhp and better gas mileage.

On the same website was a 1" spacer that goes under the throttle body to increase air flow in a vortex and had gains of 8rwhp ($89 bucks!!) and it was a quick bolt on.


So many options I just dont know what to do. That is why I am asking all of you guys!!!;)
Just send him a PM about whatever it is you're looking for. I don't think he posts in the public boards a whole lot, but I see him around the moderator section.

Lifter tap isn't a huge deal. Our engines are sort of notorious for making a "lifter tap" noise. Is it actually lifter tap? No idea, but my car has it too.

Best starting mod is exhaust, in my opinion. It won't do much for performance but you'll go from being unnoticed to turning heads in no time just because you'll be loud and have an aggressive sound.

Don't worry about throttle bodies. They can claim gains all day long but your stock throttle body flows better than you think. The only time you actually need to upgrade your throttle body is if you decide to go with a turbo/supercharger. Don't worry about the throttle body spacer either. It's an expensive paperweight. Again, they'll claim some incredible gains I don't think they've ever had any customers actually back up those claims.

Lol yeah, there are a lot of options. Mustangs have one of the biggest selections of aftermarket parts. I would recommend you start with the exhaust, then pick up a tuner (they're great for auto transmissions), then gears and a tlok (you'll need an install/bearing kit for it all), then Winstar upper intake. Also, you might want to give your car a good tuneup. That may help with your low MPG problem.
 
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