White smoke occuring during early morning engine startups is normal if and only if mawawala na yung white smoke after warm-up. The reason is that since diesels need high temperatures from compression to ignite the fuel e ang nangyayari sa umaga e masyadong malamig ang makina kaya fuel burns incompletely. at isa pa, the piston rings have not yet expanded to their working fit thus the insufficient compression.

Pero kung hindi mawawala ang white smoke even at loaded conditions, here are some of the possible causes:
1. Poor atomization ng fuel
2. Injection pressure too low or nozzle assy damaged
3. Insufficient compression pressure
4. Fuel injected too late
5. Fuel contains water.

From my experience with my pick-up (4D56), parating ganun lalu na ngaun malamig ang panahon. Nanginginig during startups at may white smoke pero after warm-up nawawala din. At ganun din yung traktora na ginagamit namin. White smoke at cold starts then wala na after warmup.

If ever blue smoke ang present, it means oil is getting past through the piston rings then into the combustion chamber