Is it worth getting a a chassis Dyno?

It’s really troubling me trying to figure this whole drag on my driveline at around 65mph.

something is wrong yet no codes. My truck never had boost when I was going downhill or coasting bobtail. Then it registered boost and the truck started slowing down very fast when I let go of the peddle.

I did a couple of wide open throttles all the way up to 80mph and it seemed to fix the boost issue for a day or two. Yet there was still a drag on the driveline.

so I’m thinking now that the VGT turbo is getting stuck, and also in conjunction of another issue on the drive line.

I’m also thinking there is back pressure on the exhaust caused by the DPF filters. I’m going to remove them and clean or replace them.

Would the transmission cause the drag? It’s not slipping. Thinking maybe a bearing or two in the tranny making it hard for it to keep its speed.

I guess my question is would a chassis dyno show me a bigger picture or just run the Diagnostics software during a regen to see if anything is wrong?

 

that’s the thing in neutral it’s good to go. In gear is when the issue starts.

 

2013 Cascadia DD15 direct drive tranny. Top gear 65mph is about 1450 or 1500rpm.

so it is in top gear.

no jakes are off, but I’m thinking maybe it’s not fully disengaging but everyone said that’s not possible.

 

that’s what I’m thinking, since the jakes are hi, mid, low on it. I’m thinking what ever is controlling it is not fully disengaging it, since it only happens at high speeds and high rpm’s.

but my question is can it be engaged even when under throttle?