A4 tdi intermittant black smoke

[smilers]

I have an early A4 TDi 110 which black smokes at irregular intervals. Cruising or pulling away but not in any particular pattern. At cruising speed all is fine then there is a very small dip in power and the engine feels slightly rough followed by big black smoke, then clears and is then ok again. Egr or mass airflow???? No faults shown when had diagnostics checked. Please help.

[GreenV8S]

That's normal for some diesels isn't it? I forget the reason, but it's deliberate.

[smilers]

I have had loads of diesels, trust me this amount of smoke is not normal.