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Ok, so here's the deal. I took my truck on a 1200 mile round trip to see family for thanksgiving, and on the way there the truck ran great. I averaged 19.67 MPG, but I was empty and not pulling a trailer. So then on the way back I was pulling a 24 foot flatbed trailer hauling a steel flatbed that I am going to put on my truck (weighs a couple hundred pounds). The truck had no power and got 10.32 MPG on the return trip. Also the ABS and BRAKE lights are now on and when I rev above 2300 RPM's I can hear a hissing noise from behind the dash, it sounds like it is comming from right behind the airbag on/off switch area, but it is hard to tell for sure (also it makes this noise even in neutral revving the engine).I also noticed that I was getting no black smoke at all, not even when I would go into a long hill and push the throttle all the way, it almost feels like I don't have any throttle after 3/4. I was having to down shift, and barely dragging over the top at 45-50 on hills that I usually pull in 5th at 70-75. So I stopped and looked things over and found nothing obvious wrong, so I unhooked my van aken chip to see if that changed anything, it didn't seem to make any difference, actually maybe a little less power if anything.At first I thought that I wasn't getting any boost pressure (I don't have a gauge on it), but if that is the case I should have black smoke. It feels like it isn't getting enough fuel maybe.Any ideas of what I should be looking at would be greatly appreciated, because I have to take it again this weekend on a snowmobiling trip.Thanks in advance Oh, I also pulled the codes and only got a P1693 code, I can't get the cheap code reader that I borrowed to show the companion codes that would go along with the P1693 code.

http://www.dieselpowerproducts.com/p-7531-budget-rv275-24-valve-cummins-fuel-injector.aspx if no one has seen this yet I wanted to let everyone know that dieselpowerproducts.com is offering a cheaper version of bosch's RV275 injectors. They say it offers all the same benefits as bosch's product. Right now they are running a sale and are only 49.99 a piece and free shipping on orders over 100.00. So if you have been looking to get these injectors but are on a budget check out this alternative product. I just ordered mine the other day, I will let you know how I like them.

Hey guys, new to the forum. I have a '98 Dodge Ram 2500 Cummins 5.9L 24valve automatic 2 wheel drive 3:55 rear axle ratio. I have done literally everything I could possibly do to my truck to improve the mpg. Yet, I cannot seem to get anything over 15-16 mpg in the city and hwy can vary from 16-22 mpg. Current mods are afe cold air intake, airdog 100gph pump, rv275 injectors, smarty tuner, 4" straight exhaust, IAT fooler, scanguage 2, tires are toyo m-55 245-75-16 filled to 80 psi. The truck would get 15 mpg city/hwy bone stock with a 3" exhaust however when the fuel pressure was tested I was told that it was at 9psi at idle. I'm wondering if its done damage to the already weak vp44 I seem to see other 4x4 trucks getting 18 mpg city as for me doesn't matter what smarty setting I am on or how much timing I give it if I really baby the heck out of it I can maybe manage to pull 16 possibly 17 city hwy mix. I'm planning on changing my diff oil to amsoil 75-90 same weight as I have in there now just hoping the amsoil will help also running 5-30 amsoil in the motor with a bypass. What could be causing the mileage to be so low? Truck shows no signs of starving for fuel I have the airdog set at 18psi now but if damage has already been done not knowing how long its been running 9psi from the PO is there any test I can do without having to pull the whole pump out?

My overhead read about 16.7 to 16.9, but actual mileage was only 14.2, on stock size tires. Most driving was short trips and basically no highway miles. I know that's not TERRIBLE numbers but I am hoping to get up there around 17-20 mpg if possible. I was using the overhead to adjust my driving style and it seemed the harder I accelerated (to a degree) the mileage went up, so I would try to drive it harder, I think this tank I will ease up and see what happens. But other than that, I need to fix a small fuel leak behind the motor. I think it's the stock return line but haven't pinpointed it yet. Some ideas of future upgrades are AFE Stage 2 intake, RV275's, maybe a larger intake horn? Besides that, all pumps and fluids are fresh, so what else can I look into for mileage and performance?

ok changed the injectors to rv275s from dap and mileage got a little worse:banghead: was running 5x5 than tried 3x5 now trying 2x5 the comp is tapped maybe time to untap but ill wait and see how this tank reacts went from about 15 to about 13:banghead:

I have heard people talk about fuel millage being in the 20's and maintaining the ideal 1800 +/- rpm, but iI run down the road at 55 mph @ 1500 rpm - 70 mph @2000 in overdrive, 55mph @2000 rpm with overdrive off.In order to keep @ 1800 rpm i have to run 45 mph with overdrive off or 65 mph in overdrive.I am running 305/75/16/10 tires 32.6 in tall with 3.54 gears, would changing to 4.10 gears help. I had factory size when i purchased the truck which was 265/75/16/10 or 31.8 tall and was about the same.I am getting around 17 mpg now but diesel just hit 3.99 gal and gas went down to 3.21 gal Most of my driving is hwy, very little stop and go.I thinking of upgrading to 4 in exhaust (have stock no muffler now) and rv 275 injectorsANY IDEAS ?????

Gas is near $4 per gallon, but you don't need to buy a new car to get better mileage on your road trip this summer. Popular Mechanics put fuel-sipping advice to the test by outfitting an ordinary ten-year-old car with an extremely accurate fuel economy gauge and trying out all the gas-saving driving tactics we could think of. We bring you the six strategies that work, plus more quick tips for better MPG. By Mike Allen | Popular Mechanics Tactic No. 1: Coast to a Stop Brakes are necessary (duh!), but they're inherently wasteful: They take the kinetic energy of a moving car—energy it took pricey gasoline to generate—and turn it into heat that's lost to the air. Everyone knows that accelerating until the last moment then braking hard to stop is less efficient than slowly coasting to a red light. But PM's test data (illustrated above) prove what a huge difference coasting makes. The lesson: Whenever possible, anticipate that a light will turn red and ease off the gas. Generally, the less you have to brake, the better your fuel economy. Tactic No. 2: Avoid Slowly Crawling Up to Speed Conventional wisdom says that jackrabbit starts consume more fuel. But it turns out that nursing your speed up to the limit too slowly also lowers mpg. How can that be? Cars get poorer fuel economy in lower gears, and accelerating too slowly prevents up-shifting at an efficient rate. The best acceleration rate varies with the vehicle, gear ratios and weight. But in our testing we found that taking 15 seconds to accelerate to 50 mph used less fuel than taking 30 seconds to reach the same speed, because the car entered its top, fuel-​saving gear sooner. Tactic No. 3: Close Windows and Use A/C at High Speeds It's a fierce efficiency debate: Open the windows in summer to avoid running your energy-intensive air conditioner, or keep the windows closed and the a/c on to preserve your car's aerodynamic profile. (We'll leave aside the option of sweating it out.) PM's testing settled the issue. Driving at 55 mph with the a/c running, we got 24 mpg; turning it off bumped us up to 28 mpg. Then we opened all four windows, one at a time, and lost 1 mpg per window until we were back at 24 mpg. So at that speed, it's a wash. But aerodynamic drag rises exponentially with speed_—the faster you go, the more the open windows hurt efficiency. The answer? Below 55 mph, open the windows and leave the a/c off. But at 60 mph or higher, keeping them closed and the air conditioning running will burn less fuel. Tactic No. 4: Cruise at a Slower Speed Since the power required to overcome aerodynamic drag is a function of the velocity cubed (in other words, it shoots up quickly), a car's jump from 40 to 60 mph requires less fuel than the increase from 60 to 80 mph. (The hit to fuel efficiency is roughly twice as severe in the higher range.) So go slower, right? Well, yeah, but fuel efficiency isn't the only thing that matters. Some studies suggest that the old 55-mph limit saved fuel but cost us more in terms of lost work hours. Then there's safety: Going 55 mph when traffic is cruising at 70 can be dangerous to everyone. Just don't go 80. That will drain your tank quickly—and the costs add up if you also have to pay for a speeding ticket. Tactic No. 5: Climb Slowly (When It's Safe) Imagine driving on a flat highway and approaching an overpass. From a fuel-efficiency standpoint, the best strategy is to turn off cruise control and forget about maintaining a constant speed up and down both sides of the grade. The theory predicts that, and our data prove it. The physics work like this: Lifting off the accelerator while traveling up the hill and allowing your speed to decay trades some kinetic energy (related to speed) for potential energy (related to the car's tendency to roll downhill). You regain the kinetic energy—and get better gas mileage—on the backside. While hyper-milers—who are obsessed with getting the best possible gas mileage—claim significant economy benefits from this technique, our results showed only modest gains. Two things did happen, though: (1) We drew the wrath of a lot of drivers following us, as evidenced by their single-​finger salutes; (2) We were nearly sideswiped by an impatient 18-wheeler. Yes, the method does work. But we'll save it for lightly traveled roads. Tactic No. 6: When Coasting Downhill, Leave the Car in Gear There are those who refuse to be shaken from the practice of coasting downhill in neutral to save gas. This is a bad idea no matter how you look at it. Let's set aside fuel economy for a moment. Coasting downhill in neutral is illegal in most states. And it's dangerous in all states. In neutral, you have no way to accelerate to avoid a hazard, and if the engine stalls, you have no power steering or vacuum boost for the brakes. If the hill is steep enough to call for hitting the brakes to keep you from gaining speed, they're more likely to overheat—and overheated brakes lose effectiveness until they cool off. They'll probably do that right around the time the police show up to take the accident report. Here's the surprise: There's no trade-off between safety and fuel economy in this case. Leaving the car in gear while coasting downhill actually is more efficient. Why? Most fuel-injected engines today use computer-controlled Deceleration Fuel Cut Off: When you lift your foot from the gas while leaving the car in gear, injectors shut off automatically, and the car's rotating tires—which are connected to the engine via the transmission—keep the engine turning and the accessories running. So, the engine consumes no fuel at all while the vehicle is coasting downhill. In contrast, the fuel-consumption rate for an engine idling in neutral falls between 0.2 and 0.4 gallons per hour (gph). Splitting the difference and using 0.3 gph for our example, idling in neutral down a ½-mile-long hill consumes fuel for 30 seconds, for a total of about 0.32 ounces of gas. Popping the car into neutral actually wastes gas. This may seem counter-intuitive, but that's what data are for—replacing good guesses with solid facts. Watch the data, and over time the savings will take care of itself. Fuel-Sipping Basics Monitor Tire Pressure Keep your tires properly inflated, because low pressure increases rolling resistance. Few drivers check and adjust their tire pressure often, but it's a good idea to do it once a week. Plan Errands Carefully Reduce the miles you drive by running all your errands in one trip. Making a run to the dry cleaner and then picking up the kids after soccer practice? Don't make separate outings. A little bit of foresight will stretch your fuel economy. Warm Up the Engine Cars get better fuel economy when the engine is warm. So if you have a three-stop run, hit the farthest destination first, then work your way back home. A fully warmed-up engine will remain at an efficient temperature even if it's parked for 30 minutes. Make Right Turns Only FedEx does it, and the MythBusters proved it works: When city driving, make as many right turns as possible, even if it means going a few hundred yards out of the way. Reducing loiter time—or idling while waiting for traffic to clear—saves gas. Avoid Ethanol When Possible Gasoline that has been cut with 10 or 15 percent ethanol, called E10 or E15, is an mpg killer. Why? Gasoline stores more energy than ethanol (119,000 Btu per gallon vs 80,000). So it takes more ethanol than gasoline to go the same distance. Read complete article