Diablosport Forums

I have a 03 cummins auto H.O. and just installed the 7130 last week. I took my first road trip this weekend. I have it on the performanc/economy tune. With the cruise set at 65mph for the largest part of the trip (200 miles) i got right at 17 mpg. Before the tuner I got around 21 on the same trip. Also I didn't notice a big increase in power over stock, there was some, but not what I would have expected. I had a fueling box in the past that was set on the 40hp setting, and it had more power with it. I changed to the programer because I dont like the idea of raising rail pressure. My questions are: Should I be checking for some other problem with the truck? Would one of the other tunes give better milage? This is my first experiance with a programer, so any insight would be helpful.(both MPG figures were hand calculated)

partsdan,
Are you using the Overhead for mileage calculation or hand calculating?

hand calculating, but overhead shows 17.5. Hand calculated was right at 17.0

When was the last time you changed the fuel filters on this truck?
This sounds like the most likely culprit here.

Thanks

The filter in it has about 3500 miles on it and around a month ago, I will change it this afternoon though just in case.

Yeah, 3-5000 miles is right about where you need to be changing these filters for best performance.
Let us know how it goes!

Thanks

reb0957 wrote, "Are you using the Overhead for mileage calculation or hand calculating?"

Wondering why you asked this? I was wondering if the overhead was correct after installing my performance tune due to the severe increase in fuel economy! I am currently calculating by hand the fuel numbers over several trips to get a more accurate picture. By the way, if I stay under 70 mph I am getting 23 - 24 mpg, at 75 mph I got 21.6 - 22 mpg by the overhead computer.

They are not always accurate, so its nice to log actual miles when determining mileage.

Thanks

I can tell you from experience the computer lies after mods. I get 17mpg tops on a 03' dually 4x4, automatic, cold air, pump pusher, 4" exhaust. If I was to believe the computer it tells me I'm getting 25mpg depending when I reset it. I have tried other programmers/chips and they do the same.

This begs the question, "what part of the calculations is the computer getting wrong and is it only after the mods?" I haven't check it on the Truck yet but in my Pontiac Bonnie SSEi it is dead on. It calculates the gallons used and miles driven better than I could! Now I am not familiar with the Dodge right off hand but if they are calculating fuel used with a similar metering device and the odometer is accurate, what could inputting a mod cause to change? Should I go out and ensure my odometer is still accurate or just check the flow metering system at the pump? My concern is if the improved fuel mileage is being caused by an altered perception of the number of miles driven to the high side, thus depreciating the value of the vehicle too rapidly as well as the warranty.

ranger_dog wrote:This begs the question, "what part of the calculations is the computer getting wrong and is it only after the mods?" I haven't check it on the Truck yet but in my Pontiac Bonnie SSEi it is dead on. It calculates the gallons used and miles driven better than I could! Now I am not familiar with the Dodge right off hand but if they are calculating fuel used with a similar metering device and the odometer is accurate, what could inputting a mod cause to change? Should I go out and ensure my odometer is still accurate or just check the flow metering system at the pump? My concern is if the improved fuel mileage is being caused by an altered perception of the number of miles driven to the high side, thus depreciating the value of the vehicle too rapidly as well as the warranty.

I remember when I installed the cold air box the milage shot up 2mpg, so thats a start..........

[quote="ropnjessi"][quote="ranger_dog"]This begs the question, "what part of the calculations is the computer getting wrong and is it only after the mods?"


I have the 06 Dodge too. That overhead MPG is complete junk has been from day 1. Even in magazines I have read they said it was showing 3-5 mpg better than actual. The test was done on a stock 06 Dodge. Seems to be a common problem with the Dodge. I know my truck is the same, shows 3-5 mpg better than actual.

Could it have something to do with diesel being a different consistancy than gas?

try the tow tune. I get my best mileage with it, about 2 1/2 mpg better than the econo/perf tune.

I get WAY worse mileage with the tow tune.....empty or loaded. I do love how the low end with the tow tune get's me movin when I'm empty though lol.

ropnjessi wrote: I remember when I installed the cold air box the milage shot up 2mpg, so thats a start..........

The mileage shot up 2mpg or the displayed perception of the mileage shot up 2mpg??