12.7 Detroit smoking and popping under acceleration

Egr?

 

Some 12.7's had egr. Maybe double check cam timing. Saw an 11.1 slip time and crash the cam.

 

Check fuel pressure. I have seen people replace the elbow on the return side at the rear of the head with a regular fitting, which kills fuel pressure. The factory fitting has an 0.080" orifice in it. Double check that that fitting is on the return side, I have seen them swapped during a rebuild and it will show good fuel pressure at the pump, but have low fuel pressure in the head.

Are you sure that the injector height was right for that engine? If they're too high it acts kind of retarded timing.

Cam timing is a little hard to check now, but can be done, you have to pull the #1 injector out to find TDC.

Is this a DDEC 3? If so, was it the low-NOx overhaul kit? They require a low NOx ECM flash. I think they had a little less compression

 

Found a service manual: The items listed under both excessive white smoke and cylinder misfire are. Aerated fuel. Improper injector calibration setting(ddeclll/lV engines only). Improper valve clearance or injector height, worn or damaged camshaft lobes and rollers. Faulty fuel injector. Faulty electronic control module.
If you just rebuilt the engine you may have your old marks to double check cam timing without pulling an injector.
I have just seen cam and or injection timing cause that type thing and lean that way. These electronic engines do things to try to compensate for problems that trough me for loops.
Also built a 8V92 once that did that type stuff off and on for 3 months. Bad valve seats in one head but that does not quite fit your description.

 

So what was the problem?

 

WHAT ?????