#6 injector smokes at idle
I have been having issues with my 2000 7.3L. The # 6 injector smokes blue at idle but will fire clean at 1300 rpms . I can see black smoke when driving under slight acceleration and will blow heavy black smoke when under hard acceleration. This truck will blow normal amount of black smoke but this is excessive. I made up a wiring harness for the dr side valve cover with toggle switches so I can turn off and on each injector. # 6 when switched off will not affect the idle (rough) and it won't smoke when off . All the other injectors make a dramatic change in the idle when switched off. I changed the #6 injector , new valve cover gasket , new UVCH, and put in a known good IDM ,all with no change on #6. I get 4.8V on each injector when idling , even #6 ,so the signal from the iDM is good , buzz test is good. So now what ? I can swap neighboring injectors to see if the problem follows the injector. Any other suggestions?