Cummins 605/2050 immediate RPM drop issue

[WICT800]

(10-22-2021 )schISM Wrote:  I had the exact same issue with a 22’ Peterbilt I purchased earlier this year. It was as if the VGT stage of the engine brake was active at all times except during actual engine braking. It would do this until the oil temperature reached 210f. Shifting around town was just ridiculous and you’d have to precisely meter the throttle if you hoped to get a smooth shift. I started at the dealer level with no luck and escalated the matter to a factory Cummins shop by way of Cummins Care. No luck at all. In the end I sold it and picked up a 2250. I’m enjoying the drive again.

This is exactly it… explained perfectly, I Spoke with a service writer at a Rush truck centers out In Oklahoma and he did say they’ve dealt with this issue before and it was able to be changed in the ECM, I’m hoping I can make some progress today. It literally makes driving a nightmare. Also mine does not seem to be effected by oil temp