Have O3 HO,3500 , 112K, was reading someone elses report about simular problem. Wild Bill made comment about rail pressure, etc and that Fuel Control Solenoid , may be connected to the issue at hand.. My cummins like many others started after about 95K while idleing,, would jump down 200-300 rpm like it was going to starve out then jump up 200-300 rpm then back to normal rpm. then repeat itself.. Some days worse than others. some days not at all but most of the time you could count on it..
replaced filters, several times, drained tank, removed tanked and cleaned found some fungi growing some water contaminets, also put in aftermarket fuel water air seperator, since my OEM LP was gauging 2-3 psi WOT, and 5-7psi at Idle..
After bypassing the OEM LP, and with the New airdog fuel water air seperator, it changed the sound of the engine immensely... just got it running last night going out after I finish this write,, to test drive.. When I first started engine after install of new LP it started a Faint indicator of the idle problem mentioned earlier.. but really most has gone away. Will no better in a few hours after a 60 mile test drive..
While looking for more info on the parts that effect this idle issue, which Wild Bill got my attention reading his post to another..
Here's what I found out so far:
For 03-05 Dodge Cummins have the following parts related to the CP3, Fuel System and ECM:
2003-2005 Dodge 5.9L Electronic Fuel Control Actuator ( high pressure fuel regulator) OE# 05183245AA over $140 beans
2003-2005 Dodge 5.9L Fuel Rail Pressure Limit Valve over $340 beans
2003-2005 Dodge 5.9L Fuel Rail PressureSensor very spendy over $500 beans
2003-2005 Dodge Cummins 5.9L High Pressure Fuel Rail with Limit Valve and Pressure Sensor Over $290 beans

Just thought you'd like to know,,
which one is the problem to the irregular Idle??????
Has Anyone else been down this road. Your help appreciated

Thanks
Ciaira54

 

Two ways of checking the FCA. Fill the fuel filter canister full of 2 stroke mixture oil and start the engine, is the surging idle stops its the FCA. Another way is to remove the FCA and shake it, if it rattles , it's ok, if not, it's sticking and needs to be replace.

MikeyB