How best to increase fuel mileage?

[mrpotts]

Hi,
I have purchased a new (used) 2004 Mazda B4000 2WD Dual-Sport with 11,500 miles. Has anyone done any mods to increase fuel mileage or know of any?
Thanks,
Phil

[Tyranitar]

Increase the exhaust size by 1/4" USe OEM air filters. USe OEM spark plugs and wires. This is about all that comes to my mind. Anyone else have any suggestions? The B4000 is not the fuel economy model, but some people can get better than 20 -22 mpg in them.

[Kyrasis6]

Well you could upgrade to a low resistance performance spark plug wire and MSD or similar ignition. Performance wires need to have atleast an 8 mm insulation but 9 or 10 mm wires are highly recommended. No solid core wires as they will screw up every electronic device in the truck. Stay away from Accell products the are all junk. With the low resistance wires you should probably increase your plug gap about .005" from stock otherwise the system will not be able to consume all of the available voltage and you spike the ignition coil, over time this will cause it to overheat and fail.

If you get a performance coil, like an SS Blaster coil or something also increase the plug gap another .005" to prevent the same problem. If you go with an MSD box or other big ignition upgrade change your plug gap to whatever is recommended for that system by the manufacturer.

The oil in K&N filters screw up MAF sensors so I wouldn't use one, some other dry high flow filter may help but it is probably best just to keep the stock one.

Most other things to help out fuel milage are probably too involved and cost too much to be economical. On some vehicles upgrading the exhaust does help milage especially on older mazda trucks.

A bed cover will help reduce drag and help gas mileage but most of them cost so much it would take over a year for it to pay off. Leaving the tail gate down actually increases drag and decreases fuel milage because the tailgate creates a pocket of air behind the cab that actually allows air going over the truck to pass completly over the truck. With it down the air comes down and hits the bed causing drag.

Changes to gearing and stuff might be possable but this usually costs more money then what its worth and may have negative side effects at other speeds or conditions. For instance I changed the gearing in my truck and it gets great milage at 70-75 mph but at 55-65 mph it actually gets worse gas mileage because I have to keep it at a higher rpm in 4th gear instead of using 5th. Most of my driving is on the interstate at 70+ mph so it works for me.

Usually the best thing to do on any vehicle that is 96 and newer is just to keep up with maintenance. Tire pressure and alignment also has a huge effect, running bigger tires to decrease engine rpm doesn't work because the larger diameter tires put a much larger drag on the engine.

[Tyranitar]

I have never seen a performance wire set improve economy over stock wires, though they are useful in high RPM applications.

Yes, a bed cover should help, and also removing the tailgate, or useing a slotted tailgate should help a little at freeway speeds.

Also, if you have the luxury of breaking a new engine in, to help insure it gets the best power and economy it can, run it hard for the first 20 mins or so, with lots of hard acceleration and deceleration. It does make a difference, especcially 100,000 plus miles down the road, really helps the engines last longer. A hard break in must be performed with the engine warmed up, and once arm, it should be done immediatly, rather than a few easy runs first. If there are close tolerances, or burs or other problems with the engine, no amount of easy running will fix it, and I'd rather have it cause a failure sooner rather than later.

[Kyrasis6]

With the low resistance wires you should probably increase your plug gap about .005" from stock otherwise the system will not be able to consume all of the available voltage and you spike the ignition coil, over time this will cause it to overheat and fail.

If you get a performance coil, like an SS Blaster coil or something also increase the plug gap another .005" to prevent the same problem. If you go with an MSD box or other big ignition upgrade change your plug gap to whatever is recommended for that system by the manufacturer.
[/b]

I have never seen a performance wire set improve economy over stock wires, though they are useful in high RPM applications.[/b]

That is because most people do not increase their plug gap to increase the restistance between the spark plug gap to be able to use the power. Every time the primary circuit closes all the power that isn't consumed gets disapated in the coil via a small power fluctuation that causes heat. Every component in the secondary system has resistance which consumes power, the coil wire, rotor button, gap between the rotor button, distributor contacts, plug wires, spark plugs, plug gap and the return ground path back to the coil all consumes power. The trick is you want all the power you can consumed accross the plug gap, the more power there is to consume there the more you can increase plug gap which gives the spark more area to ignite fuel. Putting in low resistance plug wires frees up more voltage to be consumed between the plug gap but without increasing the gap it will consume the same amount of power regardless of how much extra power is getting to it. On old worn out ignition systems performance wires often help because old spark plugs take more power to get spark so performance wires will help jump the gap, same goes if the ignition coil is weak the wires will help make sure all the voltage from the coil is making it to the plugs.

A lot of your newer high end cars if they still have plug wires already have low resistance wires from the factory.

Waste spark systems have even lower resistance because it puts two plugs in parallel, and the total resistance in a parrallel circuit will be lower then the lowest branch in the circuit.

Removing the tail gate is no different from putting it down it will cause drag because the vortex of air behind the cab cannot build to keep faster moving air off the truck. Without that vortex the air comes down and hits the bottom of the bed creating drag.