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2003 427 Boost Gauge Question


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I've got an 03 granite tractor with a 427 and mack 10spd.I am always pulling heavy loads 120,000+.I think there might be something wrong with this engine,It has very little power and the engine is not very responsive.I've checked the turbo for cleanliness and bearing play,I also put 6 new injectors in and adjusted the valves.still no power.On a long hill the pyro gauge will sit almost at a 1000 degrees.I'd like to add a boost gauge in my dash.There is a spot for it in the gauge cluster.Can I just buy the factory gauge and plug it in or will the have to turn something on in the ecm???Also is there any way of safely adding more power to this engine..I'd like it to run like my 2004 460.I asked my local dealer about a power upgrade and they told me it would be so expensive they wouldnt even consider it...THANKS FOR ANY HELP.... :mack1:

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If I recall the 2001-2004 Mack engines were said to be pretty weak when compaired to others with the same HP. I have driven a few that felt lifeless even empty. As soon as the engine felt like it was coming alive you had to shift. Even tho it would pull 80k it never felt like it wanted too. I think there was a program to turn up to 480HP but the EPA killed that a few years ago. ??

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if you look on the intake manifold you will see two plugs on the top, thats where you will get your boost reading from. I would check out summit performance for the gauge, thats where I bought mine(check out my pics)no ecm adj. need if you use mech. gauge which is the "real" reading anyway! check out north west, or rochester fuel for upgrades I been running big turbo and inj for over a year runs a little hot up hill with foot in it(but its a Rb so to be expected) good luck

Edited by bobo
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:thumb: I have been thinking about larger injectors ,it just sux because mine only have about 5 thousand miles on them.They cost me almost 12 hundred from MACK and I'd hate to turn them in for cores.When you say egts run hotter up a hill, what can I expect for temps?R U using stage 1,2 or 3 injectors? How about raising the fuel pressure at the transfer pump, can that be done?? THanx in advance!!!!!!!!! :thumb:
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I brought the truck in to the dealer today to have them give a look.They found 2 troublecodes stored in the computer. high voltage in jake # 1 and fault in injector circuit #2. Still havent got the truck back,they feel the problem is a wiring issue...I ordered a service manual but it hasnt come in yet. I dont know where to begin looking .hoping a manual will have some sort of troublshooting charts in it

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have you checked your fuel pressure? it is commonly over looked at shops, it should be running 59 at idle 80 at full throttle, the electronic motors like to spin the nylon gear away from the pump shaft. is it a vgt turbo? is there a large position sensor on the side of the turbo?

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Factory spec for that year is 29-37 psi of boost at full load. Take the truck to a Mack Dealer and tell them you want the "throttle responce program" downloaded on the VECU ( and they will calibrate the throttle pedal) and any new software/datafile for the engine and vehicle ECM's. Its a free download from Mack, you should only pay labor, 2 hrs max. We do this to all AI engines and it make a big difference. It helps with the poor throttle responce between the gears. Most AI 427 and AI460 are the exact same engines but with different datafiles for different HP levels. The dealer can submitt a HP conversion request form to Mack, sometimes its just a free download to up it to 460HP, + labor to install program of course. However I did have a 2005 CT713 with a AI427 and requested a HP conversion to 460 HP and was denied, I called the engineer and he said on some AI's they couldn't bump up because of EPA reasons? Good Luck

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I am going back to the dealer tommorow.I will have them check fuel pressure and download throttle responce file..Thank you very much for all your responces and ill be sure to let u all know how i made out!!! I usually like to make all my own repairs , however , I've got a service manual on order for several weeks now and these electronic engines are a little tricky

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let us know how it goes.. Sounds like you may be on to something.. boost looks good to me. but I know more about the mechanical engines. have little info with the new stuff. does it blow any black? most of the new elec engines wont.. if it is throwing black and there is no power it could be a boost isssue or something with the timing or turbo etc... hopefully that pedal reprogram gives it some life. I was not impressed with the lack of power with my friends 02' 427 mack with a 13 speed. my little 285 maxidyne with a 6 speed would walk away from it thru 1-4 gears and holds its own all the way to the middle of 5th gear.. h

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  • 4 weeks later...

Well I got the truck back from the dealer...They said It had a really outdated program file in the computer and they downloaded the latest greatest file for a 427,atleast the best the could do and still be emmisions compliant! The truck runs a lot stronger , still not as strong as my 460, but acceptable.My next step was to relace my muffler with a freeflowing unit from pittsburgh performance. What A Difference!!!! Lowered my EGT,s by almost 150 degrees AND picked up about 4 pounds of boost.It was a little bit of a pain in the as% to install ,being a 5 inch pipe where as mine was a 4 inch inlet 5 inch outlet. that wasn,t too hard but this muffler is also a 10 inch diameter where as mine was a 9 inch.A little fabrication to the muffler mounts and pipe and all is well...The muffler cost about 160 dollars plus about fifty bucks for clamps and such.Best couple of bucks I've spent on a truck in a long time!!!!!!

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