I have a 2004 mack vision with a 350 engine. I sometimes get a 4-5 blink code and the turbo drops boost. I thought it was the actuator pin so I removed it, cleaned it, and lubed it. It seemed to be fixed but then it came back. It seems to work better when it is fully heated up. I checked the maintenance records and discovered that the turbo was replaced about 2011. I also get a flutter in the control and I can see the actuator moving in and out as the control module applies pressure then vents it. It almost seems like it is hunting for a position some times. I put it on an independent air supply and the actuator goes from upper stop to lower stop with about 80 psi. I was told that the actuator/sensor needs to be replaced, and I don’t mind doing that, but I am not sure how to determine if that is truely the root cause. Can someone give me some advice here.
The turbo that is currently installed in the truck is 631gc5176DM12X