2000 Volvo V70 2.5 TDI excessive black exhaust smoke

Black smoke is rich mixture, so something is wrong with the fuel management system. Get is connected to a pro grade scan tool computer and check long term and short term fuel trim. Check for fault codes on sensors.

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TDI I take is turbo direct injection so if that is the case you have a turbo problem or a split intercooler
what ever , the air/ fuel ratio has altered to excessive fuel
the noise could be a blown intercooler hose , split intercooler or turbine wheel in the turbo breaking off
Take it in for a proper diagnosis and have the codes read

Don't sound like a fuel pump,replace fuel filter and see if it fixes.

Is this a diesel TDI PD ?? If so i had the same problem with one of these TDI engines and traced it to the crank sensor signal implausable. The revs would start increasing with no pressure on the throttle, lots of black smoke and then cut out. The crank sensor wiring was at fault in this case. The ECU didnt know where the crank position was in relation to the camshaft and was guessing when to inject the fuel. Hence the black smoke ! Hope this is of some use.

what colour smoke ?? blue smoke is oil ,worn rings or valve guides ,or oil seeping into cylinder where oil passes through head gasket to lubricate cam ,white smoke is water ,head gasket ? black smoke is excess fuel

Not to worry. Run the engine up to operating temp before jumping to conclusions and let the heat burn off any excess oil. A leaf will not do any damage.Do not let the engine overheat while idling and if the oil light comes on switch off immediately.
The smoke from the exhaust is oil deposited by oily assembly hands just burning off. It should dissipate after about 15 minutes at most.(or 5 miles' drive)

It is hard starting my VW 2003 Jetta. It usually take 5 to 10 cranking before it turns over. Then it run normally. It only happens when the car has not been driven for about 6 hours.

VWjase

If you have a lot of black smoke then its over fueling getting to much diesel to the cylinder's. Sounds like an injector problem with the slight knocking noise. Che ck the return pipes are not blocked. If the smoke is dark brown then this is a problem with the valves on the intake manifold which control's the intake of exhaust emmisions.

When did you last replace the air filter?
Check the air filter it may have been clogged by dust.
If its (air-filter) ok thn you will have to get the injector pump and the injector nozzles serviced.
Hope this helps!

blue smoke is a sign that its burning a little oil!usuallyits oil seeping thru oil guide seals