poor mpg

one of the things you can try is to get yourself a cold air intake (k&n filter can work well too), a better flowing exhuast, and the Edge Chip to control how your fuel system is being used....if low on cash...go for the intake and that should help. sometimes a bed cover can add a couple mpg's as well.

AFE stage 2 CAI is the best out there for the hemi. heat soak on these engines also starts at 190 degrees F. putting in a new t-stat will also help a bit. adding in a full exhaust system will help out also. and there is the chip to add that would help with all these mods. i would start with the AFE and t-stat. $400 and about 2-3 mpg increase (maybe even more).

I have an 03 2500 5.7L with the flashpack superchip, custom dual flowmaster exhaust with no cats and a k&N cold air, would changin the t-stat be a good plan, also Im not sure why but at full throttle it shifts at about 6600 , right when it shifts it coughs, when I have the wheel turned it even jerks a bit, any ideas?

the tstat is a good upgrade. gives more power and fuel efficiency thats lost to heat. no idea about the cough though.

one other thing that can do it is the knock sensor. if its bad ,just unplug it.

Right on, I will get on both of those, thanks guys

out a tuner on it. if you supercharge it that actually makes it get better gas mileage too. superchips or hypertech will give you the best gas mileage. and getting 11 out of it is actually decent. its a hemi. its a big motor. its meant for power and torque not gas mileage. if thats what youre looking for might as well trade it in.

Hypertech and superchips are not the best for the hemi. Diablo is the best for tuning on the hemi.

Im not expecting better gas milage out of it, thanks for the leason but I know what a hemi is and mixed with a 3/4 ton I know my milage is always gonna suck, but if it is possible to bump it up a couple mpg's then why the fuck not

try dual fuel, gas and propain.

I have a 2005 Ram 2500 5.7 Hemi and there are several things that help. I use the Superchips Flashpaq programmer and I run in performance mode, which has many options. I like being able to set my wot shift points from 1st to 2nd and 2nd to 3rd and it performs better by shifting at about 6,000 rpm since you are in that peak crossover in Torque and HP. I tried higher revs but power drops off if you shift out too high and although you can let it rev to 6600 rpm you are not making your best power at that rpm, at least on an 05. Airaid intake, I originally had a Gibson Twin sport cat back but when it rotted out since it was too loud I welded up a cat back duals through a Flowmaster 40 dual exit. True dual would breathe better. Now some may laugh but I have the inline Fitch fuel catalyst system that keeps fuel fresh and bumps octane 2 points. You are supposed to run 91 octane but I use midgrade 89 and have no issues. Now it depends on the time of year and where you live. I'm in CT and we have way too much ethanol in our gas and the winter blend is the worst for fuel economy. I kind of wish when I bought it I got the '06 with MDS but I wasn't confident since it was the first year in Dodge trucks. Now really if you are heavy on the pedal fuel economy dives and I only average slightly more than you do in the spring, summer and fall since colder air gives you more power but less fuel economy. Now if I'm mellow and on the highway mostly I will average about 13.5 at 70-75 mixing in some local driving. Highway with cruise control on I max out at 15.5mpg and my 2003 was 2wd it did a little better than my '05 4wd. Spark plugs! Well they came with Champion copper and in the manual the tell you to change them at only 30K. I did mine at 50K after going through emissions; oh if I go back to stock program I drop 2 mpg. I put in NGK's since I never liked Champion plugs. Tire Pressure makes a difference and since the 2500 is 3/4 ton you run load range E tires with a max pressure of 80 psi and I keep mine at or near max pressure. Never run any tire at less than 80% of max pressure both for safety and less rolling resistance. I run all synthetic oil in the engine, tranny, and differentials. Bottom line is that it is a TRUCK and yes-newer models get better mpg. Now I haven't done it yet but if you bought or made your own Hydrogen cell assist that will improve mileage a lot. There is a company I checked out called Aqua tune but then I can't use my programmer and I could make a better system myself. Really an engine is like a big air pump and the better it flows the better the power and MPG's. GHEMI196

If spending money to save money (better mpg's) is an option for you... Find a reputable speed shop and have your combustion chambers cc'd & polished. Have your exhaust & intake ports port matched, opened up and polished on the intake and roughed on the exhaust (polished allows the air/fuel mixture to flow better and roughing the exhaust allows better scavenging) if you want to go all out you can have work done on your intake manifold and throttle body (matched & polished). The less mismatched venturies and bumps anh humps, the better your engine will flow air in and out. Good performance = good performance = good air flow.

The HEMI can be a tricky beast to tame when it comes to economy. Check you state vehicle laws pertaining to Catalytic "chokers"! South Carolina and a few other states do not require them. If the state you live in requires them, search for an exhaust specialist who can make an easy switch out pipe. (time for inspection put the cats in. Once your HEMI passes the excessive fuel consumption test take the cats off). Invest in a set of quality performance mufflers and run a dual exhaust system with a cross over pipe. Custom headers are a plus but not necessary as the stock manifolds on late model HEMI's flow well. Next up, don't just invest in a K&N drop in! Spend an extra $150 and get the cold air intake. With the cold air intake you will need a quality OBD II performance chip system with monitor. The computer will sense the sudden increase of air flow coming in and dump more fuel into the compression chamber causing less economy and defeating your efforts which is why you need the OBD II performance chip. If you have the economy and horsepower robbing mechanical fan and fan clutch ditch it and go with an electric fan kit. Beware, the Hayden electric fans you get at the fast food style parts stores are for enhancing an existing mechanical cooling fan set up, not replacing it. If you have a sign manufacturer in your area you can snatch an electric fan set out of a police crown vic and have it fabricated into your stock shroud. Just make sure it is wired up correct using a relay and a 30 amp breaker. This set up cost me $90. You can get an aftermarket cooling fan kit to replace the mechanical fan which drops in and plugs in for around $750. I observed other replies stating the experience of the famous late model burp from 1st to 2nd shift on a high RPM strain. The solution I found was changing out my stock fuel pump and regulator with an Aeromotive Stage II system in addition to changing out the stock ignition coils with a performance set. That said I would stay away from the Accel brand and lean more toward Taylor Made or D.U.I. brand ignition products. MSD products are OK if you stay away from the low end product line. The MSD #5517 coil packs work great. I found that tuning my 05' Ran Quad Cab 5.7 HEMI for economy was a bit frustrating however paid off with unbelievable results once I completed everything.