03' Big Red Posted May 17, 2012 Share Posted May 17, 2012 i have a 2003 RD688Sthis 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 067246thanks for any help given !! Quote Link to comment Share on other sites More sharing options...
shortstack Posted May 17, 2012 Share Posted May 17, 2012 Have you done anything yet such as checking the air and fuel filters? Trey Quote Link to comment Share on other sites More sharing options...
03' Big Red Posted May 17, 2012 Author Share Posted May 17, 2012 yes, air and fuel filters are changed on at regular PM. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted May 22, 2012 Share Posted May 22, 2012 Looks like on 4/12/11 a Mack dealer set up the step 12B downloads and new datafiles for the engine. Its shows the dealer downloaded the new files in their laptop but the dealer didnt send back the confimation file saying they were installed into the truck. Not saying the dealer didnt install them but who knows. It shows u have a fuller 8LL trans and 4.42 rear gears. Truck came with 22.5 wheels but no tire size listed. If your running full size 24.5 tires they might be to tall for your 350 HP. We sold 2 CV's with 400AI's, 8LL trans, 24.5 tall rubber and 4.17 gears. Almost had to buy them back from some very unhappy customers. The AI engine has a very tight window for every thing to work right. Any one thing out of wack/changed and its low power complants. The good thing bout the AI engine is to do HP upgrades you just need to change turbo and injectors and download. Older ETECHs you sometimes have to change the camshaft keyway. In your case you might need to upgrade to a air fanclutch as well. Quote Link to comment Share on other sites More sharing options...
03' Big Red Posted June 22, 2012 Author Share Posted June 22, 2012 Looks like on 4/12/11 a Mack dealer set up the step 12B downloads and new datafiles for the engine. Its shows the dealer downloaded the new files in their laptop but the dealer didnt send back the confimation file saying they were installed into the truck. Not saying the dealer didnt install them but who knows. It shows u have a fuller 8LL trans and 4.42 rear gears. Truck came with 22.5 wheels but no tire size listed. If your running full size 24.5 tires they might be to tall for your 350 HP. We sold 2 CV's with 400AI's, 8LL trans, 24.5 tall rubber and 4.17 gears. Almost had to buy them back from some very unhappy customers. The AI engine has a very tight window for every thing to work right. Any one thing out of wack/changed and its low power complants. The good thing bout the AI engine is to do HP upgrades you just need to change turbo and injectors and download. Older ETECHs you sometimes have to change the camshaft keyway. In your case you might need to upgrade to a air fanclutch as well.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. Quote Link to comment Share on other sites More sharing options...
03' Big Red Posted June 22, 2012 Author Share Posted June 22, 2012 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? Quote Link to comment Share on other sites More sharing options...
03' Big Red Posted June 29, 2012 Author Share Posted June 29, 2012 here is a update, i had the valves adjusted and a new fuel pump installed, it's a completley different truck. I have Lesher Mack in Lebanon Pa checking as to how much Horsepower they can put into the ECM without changing turbo and injectors. the least I'll do is have the 12B installed. Quote Link to comment Share on other sites More sharing options...
03' Big Red Posted July 25, 2012 Author Share Posted July 25, 2012 crap, well that didn't last long biggest POS i ever bought, shoulda kept my '88 Diamond Reo Quote Link to comment Share on other sites More sharing options...
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