On a newer Eagle Cummings vs. Maxxforce?

I bought a 08 Prostar from KW in Spokane. 42,000 out the door. 500k on the truck, with an APU too. Didn't think it was a bad deal, traded old truck in, financed the balance. Got the extended warranty out to 1 million miles. Truck has ISX, was set at 485hp/1650 torque, now at 550 hp/1850 torque, 10sp trans,3.55 rears, 244 wheelbase, 73 inch sleeper, 10 alum wheels. My big ##### with the truck is fuel mileage. My old Classic averaged 7.2, Prostar is averaging 6.2 to 6.5 mpg. I realize it is a EGR engine, but the aerodynamics are so much better than the Classic, I figured to get close to the same mileage.

 

Was the truck undriveable at 485hp?

 

Had an09 w big cummins....miss that truck. Currently running the 13 maxfarce, it has given me some grief but if you can get it cheap it may be worth the risk. Not a motor out there that is trouble free, anyone tells you that question their memory or sanity

 

No, it drove ok, just lacked in power on the hills. I only gross 54k, and the c-12 in the classic pulled better than the ISX.

 

The 10 spd trans may be causing the mileage drop, it is nice to have a 13 spd and be able to split when you need to get up those hills without dropping a full gear. You might just have to play with your road speeds till you find a sweet spot. We have a local fleet with about 20 trucks with ISX's. He gets the best mileage at 62 mph. If he runs them at 65 it really drops off. Anything over 65 and most EGR engines really suck the fuel back!

 

I've been driving at 65 to 70, just like the old truck. I'll try running at 62, see if it helps. I agree with the 13 sp. I've always like that trans way better than a 10 sp. I'll change it out eventually to a 13. I've read that cleaning the mass air sensor, and egr tube can help fuel milage. I'm going to do that in the spring when the weather warms up a bit.

 

The extra 12 grand for the freightliner is a small price to pay . Heavy has helped us greatly with advice with an 09 prostar with the ISX in it my brother owns. It has been a major pain in the rear (joke about blowing it to the heck from which it came). My 2011 cascadia with the DD15 is quickly catching his in mileage . My freightliner has been rock solid so far. His truck is in its longest trouble spell now ( 3 weeks) . He bought it in June . Truly wish he has got all the bugs out ! He is running coast to coast, so breaking down every other week in getting old . Calls me each time!

 

Somebody could make a lot of money if they came out with a bulletproof EGR valve and cooler for the maxxforce I'm sure altering the programming could be a benefit too.but anything in the aftermarket is nonexistent

 

When Cummins brought out the SCR system to tackle NOx, they were able to reduce the EGR on their engines to less than 10% usage compared to the last generation. Maxxforce is going to SCR at this time. If they can also cut way back on the EGR usage I think they will have a good engine. 99% of the problems seem to stem from EGR components that are under designed and over used.

 

I know that there is a EGR delete kit out in the aftermarket. I have talked with a couple guys that have done it and have seen increases in fuel mileage from 1 to 1.75 mpg. If you never had to run in California, it might be worth doing that. I've also heard of a couple guys that gutted the DPF. That seems like it would create a lot of check engine lights/codes. Not sure if that would be true, need someone with more mechanical knowledge than I have, to say if it would or wouldn't work.