Cummins turbo surging

We have a 2004 International with a Cummins ISM 350 hp and the problem it has developed is that when pulling a hill then the turbo surges. You can hear the spool sound go up and down up and down. When you first step on the pedal starting up the hill, it's the worst and then it seems that as it's surging then it lessens and sometimes stops altogether and stays steady. Any ideas what it may be? It sure sucks though because it is affecting the power while climbing the hills.

 

We have replaced the boost sensor and it still does it. It's also not the pedal position sensor as we've replaced that too.

 

hmm... i have no idea what those are so I guess i'll have to mention it to my mechanic and hope he knows...

 

We never did get the truck looked at any further on this issue but now that i know more about it, then i've noticed that while the boost surges up and down under a load, it also at random times will open the wastegate momentarily under boost. Sometimes it does it twice right after another which causes the truck to stumble momentarily everytime it does it. Other times it seems to open the wastegate every few seconds or so under boost. And then there are also times that i can pull an entire hill and it doesn't release it even once. it's so weird. My mechanic had mentioned that sometimes the turbo actuator can cause boost fluctuation issues but he couldn't guarantee that would fix it and that was before i recognised that the waste gate was opening so much too. Could the turbo actuator cause the boost surging and also the wastegate opening issues or is it still possibly the pressure exhaust tube thingy that was mentioned above?

 

New update on the turbo surging up and down with the boost and also burping the wastegate some of the times it surges up and then down. If the truck's engine oil level is full, it does it. once it starts to get lower on the oil level, it stops doing it altogether. I dont know how low the level has to get though. It hadn't been doing it in a few months, checked the oil and it was a bit below the ADD mark. filled it to full and now it does the surging again. Does anyone have any idea what the heck being full on engine oil could cause the turbo to surge constantly when under load? And it doesn't do it 100% of the time when full of oil either. It might not do it for a few mins but then on the next uphill, it starts again. GRRRR this is frustrating. I guess i could pay attention to what oil level it stops doing it and just keep the level no higher than that? It hasn't always done this either. It just started doing it a couple of years ago out of the blue. I really hope someone has an idea for a fix besides running it below a certain oil level.