Hello--I picked up an '01 Cummins a month ago and am just finishing up the first tank of Biodiesel (B99). I have done some research here and it looks like the Smarty S-03 is one of the most recommended tuners. One of the built-in programs for it is for better fuel economy. The Smarty website claims an average of 2 mpg increase. Thus, I"m looking for some first hand experience with fuel economy.

This truck is my daily driver, and at roughly 40 miles per day, I would like to make it as efficient as possible. I've got new tires, aired up to roll more efficiently, and I'm easy on the go-pedal anyway. (but at least with the Smarty, I can ramp up the power if I need it!).

For reference, my truck has an auto, 3.55 gears, 4x4, quad cab 2500. I had originally wanted to get a truck with the 4.10's because I think the tow rating is higher, but I don't really need the extra amount and would rather have the increased mpg with the 3.55's.

 

4.10's absolutely rape your fuel economy...good thing you got your 3.55.

a 3.55 truck can pull just as much as a truck with 4.10's just tune the truck.

now before you go getting a smarty, you need a good aftermarket lift pump and fuel pressure gauge.

if you still have the stock lift pump you may already be starving your injection pump for fuel...

the factory lift pump in most cases can not keep up with factory fuel demand and is the #1 cause of injection pump failure. the VP44 injection pump needs a factory rated 10-20psi of fuel pressure at all times which at WOT stock lift pumps drop below 10psi..

to really make your injection pump last it should be running 14-20psi fuel pressure at all times as the overflow valve inside the injection pump opens at 13psi and returns fuel to the tank. keeping above that pressure keeps fuel constantly flowing through the pump and returning to the tank which helps keep the injection pump cooled and lubricated.

either a raptor lift pump, or a fass or airdog fuel system (with the filters) would do the trick and help ensure a long healthy life for your injection pump. plus they can keep up with above factory fuel demand..

 

smarty is a decent programmer for low end grunt and added timing for fuel economy, but it wont give the maximum potential for power out of your pump. only a wiretap fueling box will do that.

the most you can get power wise out of a programmer or non-wiretap box is 65hp.

with a wiretap fueling box you can gain up to 150hp @ the rear wheels.

 

Thanks for the info. Note that I am only looking for mpg gains, and I'm not looking for HP power increases. I'm not sure if my lift pump is stock or not (but it probably is), but I do plan to eventually replace that with something else (e.g. airdog, fass, or raptor). There's a Quadzilla M3 Max that's specially just for fuel economy, but I'm reading mixed reviews about it (and it only has the 1 "tune" with it).

 

there are other tricks to fuel economy too...IAT fooler is a home brew trick that helps fuel economy especially in the winter time.

basically add in a specific rated resister between the IAT sensor and the ECM and it fools the computer into thinking the air coming into the engine is warmer than it is, so it injects less fuel. runs a little rougher on start up due to it when its very cold out but it smooths out when the engine starts warming up.