Took a load out west this week. When I got up around 5000' and higher if I let it lug down to 1200rpm you could hear the turbo fluttering in the air cleaner. Get down into Nevada below 4000' and it does not do it anymore. C-15 Accert 550 with the heavy haul program. Any thoughts?
The turbos are starving for air and are surging. Are your air filters clean? You can easily break a turbo when this is happening. You have to remember that the air gets less dense as you rise in altitude. This means the turbos are going to spool much harder to fed the engine the air it requires
Air filters are only a couple of months old and look like new. If I keep it above 1250 it doesn't do it. Mr. Haney what you are saying makes sense and was my first thought. But why would it do this at a lower rpm versus higher?
Also could have a Variable valve actuator issue.. i have come accros vva sticking and causing a flutter..its posible maybe the atmospheric pressure sensor is faulty and causing an in range fault and not logging codes
I'd also wonder about the atmospheric pressure sensor myself. The ECM should calculate the fuel rate for the altitude differences. Turbo surge at low RPM is a sign of too much air entering the engine for the exhaust being expelled to drive the turbos. Low Exhaust Gas Back Pressure in the exhaust manifold versus Boost Pressure in the intake manifold Could you possibly have an exhaust leak before the turbo in the exhaust bellows or piping, any signs of soot?
One of the bellows has a small crack in it. The small one that is easy to change. So that could be the source of the problem?
