Hi there. I have a 2008 Mack Trident with the 500 mp8 with only 550,000kms on it. A while back, I encounted a bad hesitation in power when getting on the throttle during gear changes, but still pulled great once it sorted itself out. It also passed a bit of black smoke if you got onto the throttle slowly. I took it to the dealer and they put a new turbo on it and it did not improve, they then replaced boost sensor, injector cups, did top tune (had no clearence on some valves after previous top tune 50,000kms earlier) and still no improvement. Then I replaced the fuel pump after noticing fuel leak between it and power steering pump. Still no luck. The issue has improved a little but it's still there and seems to be worse when the engine is cold. I do notice a slight tick from motor at idle when its warmed up, but cant make up my mind if it's related. I had the EGR turned off a couple years ago after the first time we replaced the injector cups and hoping that hasnt hurt it. Any ideas?
