03' Big Red

i did the swap from 22.5 daytons to 24.5 hub piloted and it picked up 3 mph, i was pissed because everyone told me 7-10 mph,but if i would have done my homework i would have know it was a waist of money. here is a link to the Eaton road speed calculator. hope the link works. http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/ct_062746.swf

i am confused about one thing, i was commenting on another post about the same issues i am having and Daveigou said my engine should be the Etech not the AI, wich one is it ? and wich one is better?

i did have the local mack dealer check for updates but was not very happy with the service i got from them just trying to get some answers, so i never went back to have the updates downloaded. it does have the 24.5 drive tires. the truck is at a local shop today and they checked fuel pressure, its at 50 psi instead of 80 psi so they are installing a new pump then also running the overhead since that probably wasn't done by the previous owner. they suggested going to a competent dealer and getting any updates then if i need more HP they could do injectors and turbo but i am also considering a Pittsburgh Power box first since it's almost the same price but will give me better drive ability and horsepower increase than injectors and turbo...so they say, it does have a air fanclutch. thanks for you input.

Harrisburg Mack claims it's the AI 350. the truck is at Garden Spot Frame and alignment today, they checked fuel pressure and its about 30 psi low on a cold motor so a new lift pump is on the way, i hear this is a typical problem for a Mack. they will also be adjusting the valves since that most likely was never done by the previous owner. what is the difference in the Etech and AI ?

all of this talk sounds like my 2003 RD688s with a AI 350, there are many times i wish i didn't buy that truck, i sure hope there is something that can be done.

yes, air and fuel filters are changed on at regular PM.

i have a 2003 RD688S this truck makes me so mad i could cry, most times it won't pull over 1800rpm and the throttel response is horrible.there is a huge delay when you step on the throttle. i can live with the 350 HP but i just wish i could use it. some times it will pull to 1950 and some times i can feel a stumlbe under accelloration. any ideas on how to get this dog running would be greatly appreciated. if i am correct the motor is a AI 350. i am also wondering if i can reflash the ECM up to a 400 or 427 with out changing injectors, turbo and such, just in case i need more HP. the last 6 of the vin are 067246 thanks for any help given !!