Det/ problem

I also thought the he was replying to the wrong thread.

 

I thought about the throttle position sensor also. And another thing could be a bad ground or connection that causes a reduction in voltage to the ECM.

I had a problem with voltage drop with an N14 and it would Derate the engine just like yours is doing.

 

sometimes you can have bad main ground & it will act as your describing, but will not throw any codes.

 

I want you to know I am talking from experience. it was not until I changed my main hot & ground cables, along with all my jumpers on all 4 batteries that my prob, similiar to your went away. spent a lot of money going the process of elimination, by shops who never could diagnos much less fix the prob. all my cables looked good until I pulledd cack the rubber coating, saw green corrosion. anyway. that was my fix. good luck.

 

ok will try to help i am new here, so i have the same engine in a western star had the same problem. first off check the boost sensor plug mine was not making a good connection . this engine has a speed sensor on turbo shaft from what ive learned if the turbo speed doesnt stablize or if it over speeds the ecm will make the turbo cough mine did this for 2 yrs no one could fix this but the air cylinder that moves the rod on turbo went bad replaced that had to be adjusted by putting on a test ecm with a program to properly set this after this the coughing was gone. takes about 2 hrs to do this at a detroit shop.

 

It is also possible that the vanes in the turbo are sticking ,that has not been my problem also check pulg on v-pod ,plugged up boost sensor with soot take it out have a look you wont believe the soot that goes back into the engine ! I will have my egr disabled by summer to give the engine a little more life .

 

ok my 07 columbia with the 515 det done the same thing, check the vane adjustment , mine had to be set several times .i went through several egr valves, wiring harnesses and 2 turbos, before we figured out it was the vanes.