Ok, I just got a new to me '03 HO quad cab long bed 4x4 with an auto, this is my first Cummins as well as first diesel. The truck has a AFE stage 2 intake, Edge Juice with Attitude, 4" turbo back exhaust and the FASS system. When I come off of idle to either leave a stop or when the engine drops to an idle when moving (like slowing for a corner then getting back on the throttle) the truck will rev to about 1000 or 1200 RPM then drop 200 or so RPM then pick right back up and go like no tomarrow. If I am on the throttle and punch it to pass, there is no dead spot at all. According to the previous owner, the FASS is not that old so the filter should be good. I think if it were a filter issue it would be all the time not just off idle. I disconected all of the Edge parts from the engine and put all the stock plugs back in to try and eliminate the Edge, but the problem still occurs. The other goofy part is it does not happen all the time, but quit a bit. Anyone got any idea's? Thanks from the newbie!

 

sounds like a drop in rail pressure

 

Ok, what would cause it, how would I determine it?

 

rail pressure gauge

 

Swapped out the FCA with one my buddy had and all is well. Problem is gone as far as I can tell. So I have to buy a new FCA formy self and give my buddy back his. He told me what it stands for but I cant remember, anyone know?

 

Fuel control actuator.