2004 ISX 450hp Hard to start rough idle

I think an EGR issue will cause the engine to derate or shut down. I know on Mack engines you can put a plate in the shape of the egr gasket and block it off. It won't throw a fault code or anything. I'm not sure if you can do that with a Cummins or not.

 

How cold is cold? Doesn't sound out of the ordinary depending on the temperature.

 

EGR problems won't make it hard to start. EGR doesn't do anything until the engine is hot. The smoke still could be from a stuck open valve. The hard start is likely fuel leaking back, or the fuel is sucking some air. This would explain some of your problems. When was the last time you had a top-end-set done?

 

I was thinking gel fueled too.

 

Can you take a pic ? is it an electric fuel lift pump maybe? the next time you start it , turn the key on and let it set 60 sec before engaging the starter if it starts better, prob fuel is backing off,,, the 60 seconds allowes the lift pump to refill/ prime fuel system to pessure. -10 rough idle would be normal.

If it is a lift pump it will have a 3 or 4 bolt mount pattern might try to tighten bolts carefully each one just a little at a time. if tight the elec pump might be failing soon.

 

Most likely your electronic lift pump gasket is leaking. Pretty common problem