Black smoke even under mild acceleration

HI. My 04 Jetta is putting out quite a bit of black smoke and the mileage is in the low 30s. It's a 5-speed that I just picked up. 109,000 on it. It looks stock but I'm curious about a small air line that is taped onto the large rubber hose that is inbetween the MAP sensor and the intake manifold. I traced the line and found it is sealed shut at the other end and doesn't go anywhere. I'm wondering if air is leaking out of the intake system causing the smoke and low mileage? It's a pretty big cloud when you put your foot into the pedal! The car still feels like it has a lot of power though.

Any ideas?

Have you purchased a new air filter from the dealer or from one of the on line parts sellers like GermanAutoParts, Parts4vw, tdiparts, dieselgeek, boraparts, worldimpex ?

Some would also do a new fuel filter and deluxe timing belt. Some of the vendors listed have deluxe tiing belt kits listed.

Do you have an idea if it was chipped? Some chip folks are not so sophisiticated so their chipping can be a bit smokey.

When was the timing belt changed? And by whom? They are critical items on these cars. I don't think this is your issue, but if it breaks, it will make this issue look like small peanuts...

When I lost boost in my '04, it did not smoke. So, I don't think it's broken tube or the like. How far have you driven it? Maybe you're just blowing out some soot?

I don't know when the TB was changed last or if any other mods other than whatever the tube I described have been done. I did do a carfax that shows the service dealers name and location and I am going to try to contact them and see if I can get the maintenance records for what they did. That might answer when the TB was last changed. I think the air filter was just done, but I am going to look at that and a fuel filter. I think I will replace the intake duct that has the tube taped to it. While that is off, I should be able to get an idea on how dirty the intake system is.

How can I tell if it has been chipped? I think a VAG-com will be one of my first tool purchases. It sounds like that could tell me a lot.

I've only put 500 miles on it since I got it.

Thanks.

I don't know that a vagcom is going to tell you anything about a chip. If there is a group get together someone or a few can ride in your car and tell you.

Best bet would be to get the timing belt changed with a deluxe kit. Often people change the belt without changing idler rollers or the tensioner. Or they do not change the water pump which is driven by the timing belt. Any item fails and you have an expensive head or worse repair.

Took the hose off tonight and it looks like someone may have been trying to tap off for a boost gauge or something. I did a nice patch for now, but I will probably replace the tube so I don't have to worry about leaks.