Help me with my C15 for better mileage ??

on the e-models and c-15's the fuel is ran through the head to supply the injectors. it gets hot enough at the end of the day that you can burn your hand if you hold it on the tank long enough. or at least be real uncomfortable.

 

Ya bout everything has gone common rail most of the equipment has now to meet teir 4 standards and we are having the same problem out of them as the truck engines poor economy low power

 

I have seen the same fleet buy trucks, get from 5 to 7.9 over three months. Driver skills are a must to look at. Load weight. Bla Bla. Cat made a tool change about the time these trucks were made. That's low for a day cab. 6.5 is about normal.

 

i didn't notice any difference in design with my oem and high flow mufflers. and defenitly no difference in mpg.

my difference happened when the turbo was rebuilt. nothing else mattered. weight. speed. whatever.
rebuilt turbo got me from 4.8 to 5.4

i did lose .3 in the winter and got it back next summer. i drove a 94, 05, 3 09's. all with isx450. 5.3 in the west. 5.5 in the east. and some trips actually saw only 5.1. phoenix to salt lake however. saw 4.5 while going down to phoenix saw 5.3

 

My 2 oem 07 C15 mufflers weighed 20-25lbs more each than the donaldson hi flows, inside stock muffler black hole appeared solid, donaldsons, wide open sunshine....mpg gain too little to measure,sound difference minimal incl jake, power difference maybe if any... I avg over 7 mpg with just all the basic diy mods but going 60mph or less , and driving the minimum rpm to make gear changes is the best mod....a nice tail wind or light load helps...im at about 15% deadhead, i close the trailer gap to minimum,have to remember to readjust before loading..takes 10 seconds to slide 5th wheel with empty van on....i have the fuel wire, fleet air filter, air tabs,mufflers,and mich xda energys to round it out .....ymmv


chris

 

Sorry it took so long IH its been a long day working on a D7R. From what I'm seeing on SIS the injectors are the same part #. I would start with simple first check fuel pressure and too much is as bad as not enough on acerts, check air flow in. Pressure test cac to be sure. Usually if if everything is right turning up ecm helps fuel economy but if you have worn parts such as injector tips or turbo fins turning up ecm may help power but not economy. If all the basics check out u can try to find somebody competent enough to play with the trims and FLS FTS numbers which will change how ecm calculates but it may take more than one try. Usually overhead doesn't wear a lot normally you only see gainsof a tenth or so if its off bad you would know. Good luck let me know how it turns out.

 

Sure appreciate it. I farm, dairy cattle and grain, and have truck on the road with local home each night hauling and I run it a couple of nights/days a week and a full time driver in her all the time. My farm experience told me that a truck would get 5 mpg but was told we would get 6 doing what we are doing. Lots of people say something must be wrong do this that or check this etc. or that is not right. I just want to know if there is actually some increase to be had or a consensus that that this is normal.

 

Man I'm with you by trade I'm a heavy equip mechanic. I have hauled cattle some for a break but due to everything getting slow we just bouught an 85 model pete that I pull an end dump with scrap from little rock to the steel mill at newport some nights too. I really think its doin pretty good I always trusted my math over what ecm says. And I know you can take a hundred new trks speced the same and have a strong one and a weak one. 1 mpg over a year makes a diff to guys like us I agree glad to help

 

You should find out what rpm you should be running. I have heard that accerts should be run at low rpm. Try lugging it down to 1100 rpm. Also, read the CAT owners manual for that engine and see what they recommend. This could likely improve your fuel economy. Try driving as easy and gentle as possible and see what you get. I have a 2002 C-15 (6nz). I bought it new and had never driven a CAT. I read the manual and it recommended operating between 1200-1600 rpm for best fuel economy. And it said I could lug down to 1100 rpm for short periods. You accert is a different engine than mine. You probably need to adjust your driving style to match your engine. I was recently running coast to coast with a dry van with a gross weight of 76k and was getting 6.5 mpg. I was running 60-63 mph. To get good mpg, try driving slow.

 

We tried that and no difference however dropping to 12 th for 60 mph but then higher rpm at 1400. I am just not sold on the low lug rpm for longevity.