I just got a 2003 dodger 3500 with a 6sp HO. It has 300k on it, don't know when it was put on it but it has K@M, 5 inch exost, and an edge tuner. Computer is reading 23 mpg, have not gone through a compleat tank yet so I do not know how acurit that is yet.
Any way starts and runs good, but every now and then, some times fairly frequently. Like 2 times from a light, but some times only 3 times on a 25 mile drive. It will pop and there will be a small cloud of smoke out the pipe. Can't make it do it, and can't make it not do it, it's totally at random and at light acceleration.
Any ideas.
Obie

 

Check fuel pressures. Your tuner may or may not have this hooked up. Does it matter which tune it is on? Some programmers have a defuel limit setting based on coolant temp. On a cold engine it will defuel so the engine has time to warm up. At 300k have injectors been replaced?

 

my tuner has no settings. It's just a box that you plug in. And it makes no difference if you have it plugged in or not. I don't know if injectors have been done or not.
Obie

 

Black smoke is a sign of over fueling. Recommend checking fuel pressures and injector leak test.