(01-08-2017 )Hammerhead Wrote:  Welcome to the forum.
Fuel mileage/comparison discussions in the HH world are difficult. Trailer configurations, tire sizes, axle loads, and there are no aerodynamic equivelancies.
A freight van is a freight van. A tanker is a tanker.
We will never achieve their type of fuel mileage numbers.
A 349 excavator is not a 797 banjo is not an 857 wheel dozer, the weights are comparable. The excavator is not bad in the wind, the banjo is like a 6' diameter 30' long pipe, the 857 is like the parachutes that the military uses to drop equipment supplies. There is no way to extrapolate any reasonable comparison.
That being said, proper driving habits will maximize what you can when you can.
I run a west coast 9 axle grossing up to 190k.
My fuel mileage varies from 3-4.5, and I can some times with good conditions knock on the door of 5, but that is not the norm. When I'm empty stacked up I consistently run around 7 or higher. I'm 64-70k empty on 5 axles, and a stacked trailer is not very aero.
At 132k gross, I'm assuming you run 7axles, that's a typical range.
You should achieve 5mpg with that setup with load, wind, and terrain conditions being right, but I wouldn't expect it to be consistent.
I don't know your typical freight, but I assume it's mostly equipment that will all grab the wind differently.
I would replace the sensors that you cleaned, as the age of an 870 I wouldn't expect them to be real accurate.
Getting your injectors all working correctly will go a long way. That makes the cylinder power more consistent and the stronger ones don't have to work harder to compensate for the weaker ones.
An 870 has an air actuated VGT ipo electrical, so while they are better than a fixed vane, they aren't as good as electrical with position feedback. But there are some guys on here that are quite good at getting exceptional results.
Checking the condition of your CAC and intake tract is one if the biggest help factors. The power and economy losses here are big. Unfortunatly because of our GVW characteristics we use more torque load to climb hills and such, so this can drop off without a lot of immediate telltale signs. A 1/4-1/2mpg drop for our line of work is very easily overlooked with the common assumption that it was a little windier and this is a very realistic loss under various load conditions. This is something to not only check, but check frequently.
We can't drive like Rawze because our GVW will easily push us to too much excessive speed, but we can certainly lighten up on the fuel pedal. At 180k I'm never gonna be the first one to top of the hill, so I don't have anybody to impress, I rarely run much more than 75-80 throttle, cause I'm gonna slow down and shift anyway so why panic about it. Driving like this also keeps the heat soak load down meaning my fan doesn't cut in as often, and that's a fuel savings right there.

(01-08-2017 )un_yun Wrote:  Thanks! I have checked all the intake piping with soapy water. Had a few leaks and fixed them. I soaped up the cac, but haven't pressure tested. I changed the delta-p and cleaned the pipes for it. I also changed exhaust back pressure switch. I will change the imap and intake temp asap. I run good boost and low egt's. I also changed all the actuators. Timing where leaking so I just did all 4. Yes I run a 7 axle, and weigh in at 45k empty. I do run a lot of the Appalachian mountains. Lifetime avg is 4.4 for this truck, which I think kinda sucks because it came from south FL. And only ran there. I have 4.33 rears and try to run about 62 to 65 at around 1600 to 1750. Again thanks for mentoring me any way you can!