I’m going to try and explain this the best way I can so you guys can help me out, so today I when I was driving my truck (2005 mack ch613 dump truck) I noticed that the inlet manifold pressure needle was all the way up past 33 almost hitting 40 but not fully there and I could here a small almost like a whistle sound coming from the right side of the engine its not really a whistle but that’s the best I can describe it, and I also noticed that when loaded when I was at a stop and I took off from first gear going up the gears the inlet manifold pressure needle would almost drop to zero and the truck would move real slow almost if it had no power. Any input?
