No No NO. Never do anything that lies to the computer. Those sensors are on there for a reason. If more timing would help, the factory would have added it. There are temperature compensation tables in the computer that are there for a reason. If it's colder out, the motor is more spark tolerant, and if its hot out, the motor is less spark tolerant. The OEM knows that, and that's why those tables are in there. Trying to fool those tables is almost always counterproductive, and will cause drivability and gas mileage problems. Those guys that sell that crap have never tuned a car in their life.
The K&N brand filter is THE best filter on the market, period. It's design is just wonderful. They flow better after years and years of never cleaning the thing than a paper element does brand new. That's no hype, it really does work. Ask David Vizard, or any dyno tuner (myself included). It works because the oil/dirt in those filters literally can move out of the way of incoming air, giving the effect as if it were never really dirty. FYI, the best brand of paper air filter happens to be Motorcraft.
If you don't want to spend any real money, the best things you can do are drive easy, keep the tires full, and keep the MAF clean and spark plugs fresh.
If you want to spend some money and make significant increases, buy an aftermarket exhaust system that goes from the exhaust manifolds back, that's mandrel bent and has a consistent I.D. And get rid of the cats... of course that is illegal if you drive the car on the street. Some states inspect such things, others do not. Then, buy an SCT Xcal3, and a K&N Filter.
Since we aren't modifying the engine itself (like for racing), the best way to produce efficiency in any engine is to make sure that pump has no inlet or outlet restrictions, and that way the only restriction is in the pump (engine) itself. In our case, this means an unrestrictive inlet tubing and filter, preferably hooked to cold outside air, and an unrestricted exhaust system.
There are some catches to that phrase, that aren't so obvious. You can't buy a "cold air kit", because they will change the tuning requirements of the engine slightly. This might add power, but will probably hinder gas mileage unless you dyno tune the vehicle to remap the MAF xfer function in the PCM. Another catch is not to add "headers". They change the resonance wave tuning in the exhaust, in addition to changing the overall flow. This tuning is probably already maximized by Ford, even if the flow isn't ideal. So no headers, but everything behind them should be restriction free! A mandrel bent 2.5" or 2.75" exhaust with a low restriction muffler and no catalytic converters is ideal for mileage and power.
The SCT tuner will help a lot too, I shouldn't understate that. In it, we lean out the WOT fuel tables (factory is over-rich to be extra safe for extreme conditions like 24 hr non-stop heavy load conditions), we slightly advance the timing, and if the cats are removed, we can shut off the Cat Overtemp Protection. This protection basically dumps a bunch of fuel on the motor if it thinks the cats are getting too hot. It also will run the car real rich at first to "light off" the cat. If you get rid of the cats, we can turn off all this extra fueling, and that means a mileage increase.
These tuners come preloaded with good tunes in them, but I also have the professional tuning software (Advantage III) that allows me to custom tune the device as well. With the PCM code off your computer, I can open up the tune and look inside to see where it might be improved upon. Some have lots of room for improvement, while others are fairly decent right from Ford. Just depends on what I find inside. One thing is for sure: all cars can be leaned out at WOT for burning less fuel and making more power. Most cars can handle a little more timing, which adds spark efficiency.
The reason is Denver. They only have 86 octane, and they're way up in the mountains. All cars must be 50 state certified, so Ford has to tune for this crappy Denver scenario, even if the car is in flat, sea level Florida. Knowing you don't live in Denver, and are sure to be able to buy 87 (or better yet 93) octane, we can get rid of some of these safety margins the factory was stuck with putting in the tune. And more efficiency has the net effect of making more power AND saving gas. Win-win.
