O4 379 MBN 24234 C15 Cat Poor fuel and power

Could the engine be derating its self if the boost pressure gauge is reading wrong?

 

I took a look at one of your ecm downloads from last fall and the ecm reports show life to date your averaging 4.963 mpg. Not too bad considering the weights you haul. Looks like, if you want to, you have 2100 rpm available in every gear. That could be hurting you some if you over rev the low side of the transnmission. Try progressive shifting...you shouldn't have to get over 1500 in the low side of the transmission to pull the next gear. Also, make sure your water temp is 190 F or better, you may be bypassing some coolant past the stats which can hurt mpg. 3rd, a 379, while nice looking, has a lot of frontal area that eats fuel. 4th, watch the speed, every mile above 55 will cost you 2% more fuel...just the physics. 5th, When were the valves last adjusted?

 

10R1000 is the correct factory replacement for a MBN prefix engine, 10R0957s are for C15s 6NZ and 9NZ (and some others), 10R0958s are for 6TS and some 5EK engines (and some others). 10R0959s are marine injectors.

 

LOL, cant sleep in the truck, waaaaaaaaaaaaaaaaaaaaaaaaaaaa, seems as you must suck at truck driving because even i got 4.5mpg doing 75mph in my 290" KW when it was stock.

 

Rat: I really think I'd be looking for a different "boss"!!! That aside, Cat has raised ALL the temps in an effort to "satisfy" the EPA. C-16 fans don't even engage 'til 217Degrees!!! Oil temps are above 210 most of the time, water runs 200 +, EGT's of 1200 are common & they wonder why the pistons & other parts fly apart????? WE won't EVEN talk about blow by!!!!!!! Now that the air eminating from our exhast has to be cleaner than the air entering out intakes, as per CA> CARB, perhaps we can idle ALL out engines in order to clean up the air in the "inland empire". HAve to just LOVE our "leaders" TIC in a MAJOR way.

 

You must mean DPF C15s there, all single turbo C15 and C16 had the fan set to 217*F, now as far as oil temps go, mine still stay around 150-160 and get to 200 tops when running the mountains. Fan comes on at 190* too......... Yes thats right, manual switch!!!!

 

You are on the money there and yes they do fly apart thats why I am making changes,HP is just a by product of getting this engine running properly

 

What do you expect? 96k lbs. In a 379 that is, maybe the vulvas do better do to aerodynamics, ever think of that?