Okay, go easy on me. I did a search and couldn't find anything and this is my first Dodge I have owned. I have an '02 with the 5.9. From everything I have come across, the 5.9 is notorious for being a gas hog. I bought the truck 1 week before gas prices shot up

Anyways, has anyone bought a programmer or chip and reprogrammed their PCM and what were the results as far as mileage is concerned? I don't mind spending the $300-$400 for a programmer if it can gain me another 3 miles per gallon. I'm the type that drives my truck in a way to get the best MPG anyways and I would like to increase the MPG. I'm thinking of ditching the factory exhaust muffler and just running the CAT along with duals after the CAT My neighbor did that to his and it sounded great. Headers might be in the future too. I am hoping a programmer would show significant gains though.

So like I said, go easy on me. This truck is a whole new learning experience for me. I'm still trying to figure out how to program the garage door opener in the overhead console

 

No tuner is going to get you 3+ MPG. Those guys (like me) who do get custom tuning for their PCM do not do it for mileage. We do it for power.

 

SCT from Hemifever
$265 for tuner and 3 canned tunes.
Should gain around like 15+HP and a couple MPG, if you keep your foot out of it.
Lurk around the 2nd gen section for engine and transmission helps.
BTW, fix your plenum!

 

 

I don't let my foot get in it but what's the matter with my plenum

 

get one of these if you got $$$$ got me doing 16mpg on the Highway (75mph) and 14 on the city..if i can keep my foot of the gas lol oh, and it will get rid of that plenum gasket issue for good.
http://www.hughesengines.com/Index/p...r&partid=24773

 

Search plenum on here...you'll have more info than you can handle. Or stop over the second gen area and snoop around. You'll find all the answers you need over there too.

 

I too have an '02 5.9.. QC 4x4.. I'm getting 14MPG's overall, and this is dang near unheard of.. here is a short list, and you decide if it's worth the effort or not:

SCT ~ $365 unlimited tunes from Sean.. very slight gains economy wise.. I run the 91 w/ 93
4.56:1 gearing~ $1200.. great gains economy wise under 70mph
1.7 H&R Rocker Rollers~ $350.. this is the one item that hurts economy no matter what
e-Fan set-up~ $150ish... saved about 1.5MPG's with this alone
FI Air-Gap intake~ $600... eh, but no more worries about a plenum gasket
Shorty Headers, true duel exhaust, true x muffler~ $500ish.. for the love of God, let her breathe!! tacked on about 1.5mpg's with this..
Deep Cooling Tranny pan, extra aux cooling core, remote filter~ $400 a cooler tranny is a happy tranny.. not an economy thing, but a cooler tranny bites better..
FMS #22 genIII injectors~ $350.. better spray, needed tune, needed WB A/F
RamAir hood ~$800, cooler air in conjunction w/ CAI ~$200


the single best economy gadget:
a glow-gauge vacuum gauge~ $50.. keep that biyatch around -15 and keep your gas longer.

 

The plenum leak is an inherent issue with the 5.2/5.9 Magnum series of the LA engine. As others suggest, do a search on here or even Google. If the truck has never been fixed, it is costing you big time power and MPGs.

Chryslers "fix" for this was to de-tune the engine severely at the factory, rather than actually re-tooling and fixing the problem correctly. Once you repair the plenum, you can pick up a Superchips Tuner and gain roughly 40 HP and 80 lb./ft. of torque. Maybe a mpg or two to boot.

Nothing is ever gonna make that 5.9 fuel efficient by any stretch of the imagination, the Hemi that replaced it makes 100 more HP while still attaining a solid 25% better fuel economy, but the 5.9 is a tank, that will last forever with decent care.

I had a '98 RCSB 4x4 5.9 with 4" of lift and 35" tires, maintained very well, all synthetic fluids and couldn't get double digit fuel economy in town. NO amount you spend on "MPG mods" will get you enough mpg gains to justify the cost.

Inspect the plenum, repair it WITH AN AFTERMARKET KIT if necessary, pick you up a tuner, keep it tuned up with full synthetic fluids and fresh filters, keep tires at proper pressure and you'll be as good as it can be with that engine...

 

How in the hell did you get TRUE duals we only got one Cat and 2 o2 sensors attached to it. meaning that we cant split it, both pipes gotta go through the only 2 o2 sensors on the cat (especially through the pre-cat sensor)