John R Snyder Posted August 24, 2013 Share Posted August 24, 2013 I have a 2008 Granite with a MP8, I had 2 injector's go bad so I had the local Mack shop replace all 6, they told me the engine wiring harness was bad, so they replaced it at the same time. My problem is ever since then I have lost 6 to 7 pounds of manifold pressure pulling and 10 pounds when using the engine brake, the hills I used to jake down I now have to use way more brake. I went right back and told the service manager and mechanic, they say they cant understand what could have caused this. Just wondering if anyone else has experienced this problem. Of course they would be willing to hook up to it with their computer I'm sure, but I get tired of paying 100 plus dollars an hour or more experimenting if you now what I mean, I'm sure if it were obvious the Truck computer would give me a fault code. 1 Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 24, 2013 Share Posted August 24, 2013 Maybe they left a boost hose clamp a little loose. Or maybe they installed the injectors and the rockershaft without adjust the intake valves, exhaust valves, and setting the new injector preloads.Im going to lean towards improper valve adjustment and injector preload settings. 1 Quote Link to comment Share on other sites More sharing options...
staxx Posted August 25, 2013 Share Posted August 25, 2013 Need to adjust the valves injectors and do a leaned data reset, and pressure check system for any small boost leaks. Quote Link to comment Share on other sites More sharing options...
rsb502 Posted August 25, 2013 Share Posted August 25, 2013 Learned data reset, staxx is tired. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
Popular Post Superdog Posted August 25, 2013 Popular Post Share Posted August 25, 2013 You know,guys,this is sad. A good friend of mine is rehabbing his 1.75 million mile '97 CH right now,because he's sick of the constant " little problems" his '11 MP8 is having. With the so called technology we have today,there is no excuse for these kinda problems to arise to begin with,but when they do,why does it take multiple trips to the dealer to cure?? That's why I thank God everyday for my Superliners. 3 Quote Link to comment Share on other sites More sharing options...
mack mhe9 Posted August 25, 2013 Share Posted August 25, 2013 You know,guys,this is sad. A good friend of mine is rehabbing his 1.75 million mile '97 CH right now,because he's sick of the constant " little problems" his '11 MP8 is having. With the so called technology we have today,there is no excuse for these kinda problems to arise to begin with,but when they do,why does it take multiple trips to the dealer to cure?? That's why I thank God everyday for my Superliners.AMEN. Quote Link to comment Share on other sites More sharing options...
John R Snyder Posted August 25, 2013 Author Share Posted August 25, 2013 Thanks everyone for the input, guess I should go back and have them rerun the rack. I think I might try another shop and hope they can get it right. Quote Link to comment Share on other sites More sharing options...
rsb502 Posted August 25, 2013 Share Posted August 25, 2013 Superdog I have been asking that question since about 2004 when they started going backwards with longevity. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment Share on other sites More sharing options...
cxn613 Posted September 3, 2013 Share Posted September 3, 2013 Not sure if this will help, but we had a similar problem with our 2008 cxu 613. Our boost was dropping from 38 pulling foothills down to 20 psi. Truck had almost 300,000 on and never had the dpf cleaned. We got the filter cleaned and the truck now runs like it always did. Quote Link to comment Share on other sites More sharing options...
countryboy5487 Posted September 3, 2013 Share Posted September 3, 2013 I've seen a interesting loop hole in the dpf.. I've seen it done with good results on a med. duty paccar. They took the filter off and drilled a pattern of 1" holes thru it the dpf the equaled the area inside the exhaust pipe. The exhaust flowed freely and the ECM thought the filter was always clean, no regen, no ridiculously high temps, and better fuel mileage. There is a video on YouTube. It was done on a cummins powered Pete 330? Quote Link to comment Share on other sites More sharing options...
farmer52 Posted September 3, 2013 Share Posted September 3, 2013 The ECMs monitor back presssure (high and low). If the back pressure is too low it will set off a code. Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment Share on other sites More sharing options...
yahqub Posted July 8, 2015 Share Posted July 8, 2015 please i need a video of valves adjustment on MP8 engine, am in need of this as a matter of urgency . Quote Link to comment Share on other sites More sharing options...
upsman Posted July 11, 2015 Share Posted July 11, 2015 The Government will be the death of this country....... Quote Link to comment Share on other sites More sharing options...
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