I'm buying a '03 V6 automatic mustang in the next week or so (it's the only one in my price range around my area) and I've been reading what I could do to maybe make it work better.

it's primary purpose would be every day city/highway driving so gas milage is a concern. What I've read is the first two modifications I should make would be the read gears, a lock (?), and a handheld tuner.

I don't know much about cars beyond their basic physics workings (I'm a computer tech) so I don't know exactly what effect those three changes would have.

I gather that for my purposes the 3.73 rear gears would be best for me since I do a alot of highway-class driving. What effect do those gears have? I understand they operate on a ratio with the drive shaft but I don't know the real world driving effect. Do I just need to buy the gears to change the gears or do I need other parts as well?

The Traction Lock I'm more vague about what ti does. I understand from reading that it makes both of the wheels spin instead of just one but I don't need to make burn outs or drive off-road so I'm very unclear what the benifit is.

The handheld Tuner I'm not sure what the exact effect is. I very much understand the concept (same basic idea as tweaking desktop computer settings) but I don't know the pros and cons of using the different tuners. Obviously you can kill your car if you don't know what yoru doing but what are the benifits and draw backs of the average modifications the tuners usually make?

The car I'm getting, as far as I can tell is a stock car. I think. It's got a GT nose mask but not the GT logo on the side as well as having anti-lock brakes. To me this means it's at least a "Deluxe" trim since the standard deosn't even have ABS listed as a option I can find.

VIN: 1FAFP40413F399508
If any of you know something bad about this car let me know please? It looks and drives really nice in my view.

 

Hi dkt404!

You are correct, the V6 does have an optional ABS system (my 03 doesn't have it) that is bundled with a traction control system of some sort.

Mechanically, the 3.73 gear ratio is the final drive ratio going to the wheels. What this means is instead of 3.27 turns of the drive shaft to every one turn of the wheels, it's 3.73. This means you're applying more torque resulting in better acceleration. The downside is, instead of cruising down the highway with the engine spinning at about 2300 RPM at 70 or so MPH, it will probably be closer to 2600 RPM, using a little more gas.

A t-lok or similar aftermarket locker replaces the stock carrier in the rear differential. You currently have an "open" rear end, meaning that if one wheel loses traction (as occurs in a burnout) then all the energy will be transferred to the less efficient wheel.

If you replace that with a locker, it will make both wheels spin at a more or less equal rate, while allowing enough slip between wheels to prevent one rear tire from squealing while turning. This provides better traction in most conditions, but you will want to be a little more careful when driving on ice, as if both rear wheels spin it can cause the car to fishtail.

 

Hey, thanks for the response

So the 3.73 gears would be nice but aren't strictly required for the rest? I wouldn't mind more acceleration but the other two modifications sound simpler and I can't lose to much MPG. The tuner (if it works like I think it may) sounds like a better first option.

Better traction I don't think will be a big issue for me. I don't do racing or sharp turns and I can't think of another situation that would call for it aside from maybe heavy rain. For a day-to-day driving car is that assesment basiclly correct?

What about the electronic tuner? From what I've read it sounds like what gets the most bang for the money. What are the downsides to using one though? I really like the idea of being able to dial up specific settings to the situation (MPGs, fuel type, power, ect). But is there a catch to doing that? Would I need anything other than the tuner device?

My understanding of the hand held tuner is this: It plugs into the onboard computer and changes several settings to maximize (or correct) performance based on what program you select.

This sounds great but no place have I found what the exact effect usually is with the typical programs. Can someone enlighten me about this?

 

The tuner may very well give you better fuel economy, and you can get them with "economy tunes" for instance a 87 octance economy tune, 87 octane performance tune, 91 octane performance tune. Also the shifts will be changed in an automatic vehicle.

 

So given that I have something of a budget (which you probably guessed by me prioitizing parts) the tuner sounds like proably the best 1st mod option followed by the 3.73 gears.

Do you guys have any suggestions or ideas for me about other things I may upgrade on the car?

 

For a computer guy like you are, think of the handheld tuner in this way: there are certain parameters of the car that are controlled by the input/output of the ECU. A handheld tuner will change the output, the input being your driving conditions. A handheld tuner will reprogram the ECU much like flashing the BIOS of your computer -- in fact, that's pretty close to what you're doing.

As far as performance increase, unless you're using the tuner to correct the air/fuel mixture entering the engine or to maximize any benefits of using higher octane fuel (i.e. premium) you aren't going to see a whole lot of benefit. I'm personally dubious as to what kind of MPG increase can be had with an "economy" tune -- it's not like Ford intentionally de-optimizes our cars while they are being designed. The coolest thing a tuner will be able to do for an automatic is change the shift points/firmness. This is usually done to make the car more fun to drive.

Also, if you change gear ratios you will basically need a tuner (there are other ways to do it, but none as desirable overall) to change your speedometer/odometer, as they are controlled through the ECU on our cars.

One last thing to consider, either the gears or the locker will require professional installation. General recommendation is to go ahead and do both, so you're only paying labor once. For the record, my friend has a 2001 Bullitt edition mustang with 4.10 gears, and the V8 in it eats about 22 mpg highway. That's not much worse than a V6, which gets about 28 top.

Lockers are basically for more capable acceleration, and nothing in your differential is really going to change much in terms of cornering. An aftermarket locker is going to be stronger than your stock carrier and spider gears, but if you don't drive hard you usually won't break anything anyway. My mustang is daily-driven, and I have modified it to a small extent as a hobby. The car is already capable. If you're working on it its only to make it more fun to drive. Sometimes the compromise is a small decrease in mileage. Sometimes mileage improves. For the record, I haven't changed the gears or carrier in mine since buying it last January.

My favorite performance mod so far, for the record, is my full-length subframe connectors. They stiffen the chassis by preventing flex. I would seriously look into them for a first mod.

 

I've got a shop I trust to do the work (though I haven't asked them if they would/could yet ) so thats not a big issue.

What would I have to buy for the subframe connectors? Do they just bolt onto existing points or is it a weld job? And what does "preventing flex" translate into while driving?

As far as a tuner, I plan to put 91 octane it in all the time (thats whats around here) so I was pretty much thinking 91 economy, 91 performance, and probably the stock setting the car comes with.

What could I reasonably expect to see with those settings assuming the rest is stock or had jut the subframe?

 

Trust isn't really the issue... unless you're really good friends with the folks who work there the install is probably going to take two hours or so, so it's best to pay labor once.

Full-length subframes are a weld-in affair, and you can prep them for install yourself if you'd like, but I recommend having a shop do the welding. I paid $70 to have mine welded in. To see what the install consists of, check out this install article.

I would think a 91 economy tune would kind of defeat the purpose myself... your mileage is going to be more affected by your right foot and where you drive than anything else.

As far as what preventing flex means with the SFCs -- the chassis of the Mustang acts as a "fifth spring" in the suspension setup. The SFCs reduce the effect of that on your car. It means that your springs are going to be carrying more of the load when it comes to turning a corner or going over a bump. You will feel the road a bit more with them, but in a good way. Depending on how long you want to keep your car, the SFCs will even lengthen its life because the chassis won't fatigue so badly. They may also make the car a bit safer if you wind up in a collision, since they make the car sturdier overall.

 

Noted. As far as the 91 Economy, bear in mind; I have only a vague idea how the tuners work and what they do and what effect they have.

So what do you think the best programs would be given a 2003 V6 automatic (that is stock as far as I know)?

I think I'll get the tuner first. It's what I think I feel most comfortable with (hey, it's a computer part lol ) and see what I effect that has. As I understand it, it even works like a computer part (plug it in and work with it to do it's thing).

What is probably the best tuner for the application?

 

I have to be honest with you, I didn't read the whole entire post line by line, but if you're buying a V6 for economical issues I'd possibly rethink that approach.

You will have a slightly higher initial investment in a GT, but looking at average Gas mileage and up-keep you're looking at basically the same outcome.. The 6 cylendars get just as horrible fuel mileage as the V8's and are way less fun lol. Really just depends on how heavy your right foot is, but the bottom line is that they are both about the same.

 

WNRacing: Thanks for the ideas

Sadly though, I don't have a GT in my area in the price range and I'm kinda hard on manual transmissions anyway.

I realize that a mustang isn't going to be great on MPG no matter how you cut it but I can deal with 17-20 city and 24-30 highway. Just not 10 city and 15 highway (or something simular) and thats what I am/was trying to figure out if that woud happen.

 

My sixxer averaged about 16-18MPG city/highway, 24-30 just isn't going to happen especially on a split-port making more power than my single port, unless your drive like doobie.. lol I think the biggest issue that the sixxer inherantly has is that power to weight ratio. Heavy car, underpowered engine = more work and more fuel consumption.

Most people here will tell you that driving conservatively they can average 20-23mpg in a GT, I'm pretty sure that there is a recent mileage thread floating around somewhere on here. Ziggy has been the only person that I have heard say they get less than 15mpg on Average, which is probably due to the fact that he drives like a crazy person for his 3 mile commute.. haha!

Also, you do realize that GT's come with Automatic transmission's too, right?

I don't know, just seems to me that for an extra $2-3,000 I'd go for a GT.

 

Actually no, I didn't realize it but it's still a issue of having that extra several thousand dollars (which I don't ). The V6 mustang actually is at the upper end of my used car budget (if not slightly over). I've got the budget for the car, possable mods, and then unrelated stuff.

The mileage numbers I have are from the various car sites that say ~20 city and ~29 highway. I figured that 15-19 city and 24-29 was probably more realistic.

I'm not buying it for it's MPG but there is a floor I'd like not to bo below though.

 

Your mileage numbers are easily attainable with 3.73 gears.

 

Kobudo: Good to hear
I'll get the tuner first. As far as I can tell I'll need that for just about anything else I do anyway. 3.73 gears and maybe the lock too. Depends how far I can stretch the budget.

A tuner runs $350 near as I can tell and gears run $155 plus whatever the install costs (anyone have a guess?). I think thats doable. Anyone got a idea which 3.73 x 7.5" gears are the best to get?

I found some Motive Performance gears on AmericanMuscle but I don't know a thing about them.

Also, which tuner should I get?