rod 20 into the casing 12 until they land in a matching one of the stimulation valves 10 frac sleeves as each dart or ball 16 reaches the matching stimulation valve 10 it stops at a shoulder or u201c no go u201d see fig5 a and 5b formed into the interior surface of the valve 10 further fluid pressurizing the casing 12 from the surface pushes the dart or ball 16 downward against the shoulder or no go fig5 a and 5b resulting in shifting a sleeve in the stimulation valve 10 causing the stimulation valve 10 to open opening the stimulation valve 10 enables fluids to be pushed out into the rock formation 17 in fig1 a adjacent to the stimulation valve 10 from within the casing 12 the dart 39 s or ball 39 s 16 position along the exterior of the spoolable rod during pumping into the wellbore can be estimated during fluid pumping by measuring the amount of fluid pumped in or by cooling of the spoolable rod 20 cooling of the rod 20 can be estimated or monitored by measurements from distributed temperature sensors 19 in the spoolable rod 20 as well as by acoustic detection using suitable pressure sensors incorporated into the rod 20 of the dart or ball 16 traveling into the casing 12 the fluids pumped into the casing 12 typically have a different temperature than exists at many depths within the wellbore therefore temperature measuring along the spoolable rod 20 will generally suffice.