No Codes! No Lights!

[JimT]

(06-25-2021 )onebadapple Wrote:  Please keep in mind these nine or so hour apart regens are an actual regen where the idle fuel consumption is about 3 to 4 GPH, the hot exhaust light is on when stopped and I can disable it with the switch. This is not the problem, I can live with this although two years ago with it as a company truck I would see this about once a week or less!
This “halfway” regen goes on for about five or six hours between these and I cannot disable it with the switch but I can stop it with the cruise set button while stopped. While in this “halfway”mode the idle is at 750 rpm and idle fuel is about 2 to 2.2 GPH and no hot exhaust light and the throttle responds like it’s in regen. Hit the set button the rpm drops to 700 from 750, idle fuel goes to .7 or .8 GPH,(it’s out of it) tap the brake or clutch the idle drops to 650, idle fuel goes to .6 GPH, in ten seconds or so you hear the engine change tone and the idle fuel goes to 1.8 GPH still idling at 650 rpm (it’s back in). This is the problem.

Have you looked at the SCR system and sensors? Or hooked up insite with Data Monitor running when this "halfway regen" takes place? What your describing might actually be the system jumping into SCR Warmup mode. (Data Monitor, check aftertreatment operating mode). Low SCR temps, faulty sensors or bad wiring or exhaust leaks could trigger this to happen. Or maybe the SCR has a volcano forming from a DEF Doser Valve leak or the SCR element itself is clogging up? This could also contribute to higher exhaust pressures. Try to see what the inside of the decomp tube looks like, maybe pull the DEF Doser Valve and check for DEF leaks --- The leaking doser leads to crystallized DEF buildup in the decomp tube which will cause exhaust restriction and higher outlet NOx numbers. This buildup can be melted away with higher exhaust temps (I think roughly over 300F is needed at the decomp tube and SCR filter).