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2009 Audi A6 smoke form the exhaust

Hello Everyone!!

I am 16 a buddy of mine owns a Audi 3.2L A6 and i noticed when i drive behind him that black smoke and sometimes gray smoke comes out of the exhaust. I know Audi well and i know they like everything to be perfect so i don’t know why there is smoke coming out of the exhaust. Me and another buddy of mine think its either a bad air filter or its just a nasty and dirty exhaust pipe. What do you think? I don’t own the car but i know that it has around 50,000ish miles and he treats his car well like his baby and i would to if i had his kinda car. lol

Thanks everyone!!

If it is still under warranty, take it to the dealer asap. Black or grey smoke from the tailpipe is not ok, unless it’s a diesel. If it is a gasoline engine, there is a bigger problem than a dirty air filter or “dirty exhaust pipe”.

Thank you and yes he still has a Warranty on the car and i know that any smoke coming out of the tailpipe/ exhaust is a bad problem and the car is gasoline engine. Thanks Xebadaih i will tell him to take his car to Audi asap.

Why do I think sometimes when you are riding behind your friend we are getting on the gas pretty hard? Be careful out there.

The smoke could be normal if the car is being driven hard, but it is a warning sign to be checkout out. A new air filter is easy to install yourself, he can do that and see if it helps.

Well we park in the same “Student lot” so every day after school we talk to each other on our way to the lot then get in are cars and leave.

The car is not really being driving hard it is in Drive not Sport (Like normal) but i will tell him when i see him during a passing period to go to Audi and get it check out! And the Air filter i would have to install for him cause he really does not know how to fix or replace something on a engine.

Thanks UncleTurbo!!!

I made a mistake the car only has 30,000Ish Miles!!

It is unlikely that a dirty exhaust pipe or air filter is causing this, unless the filter is so filthy that it is seriously restricting airflow to the engine and causing it to run really rich.

A short burst of grey-ish or black smoke may be normal if he suddenly floors the accelerator, though a car with only 30K on the odometer shouldn’t experience too much of this. Basically the engine management system can’t cope quite fast enough to make the fuel/air mixture what it should be when the pedal is floored, and you’re seeing unburnt fuel vapors coming out of the exhaust. Cars seem to do this more if they’re babied, then suddenly you get on the gas after having not done so in a while.

If there is grey or black smoke coming out of the exhaust all the time, then the car should be checked as soon as possible to prevent damage to the catalytic convertor (expen$ive) or other components.

This is not to be confused with white steam, which is normal on a cold day. If you have white steam coming out all the time and it’s not jacket weather, there may be a head gasket problem.

Is the check engine light on?

No the check engine light is not on and i doubt we would see steam cause we live in FL and its not that cold out after 3PM. The smoke is black but transparent not a dead black smoke.

Basically black smoke is carbon from too rich a mix, gray smoke is burning oil.

It is not coming from the exhaust system.It is being pushed through the exhaust system. It’s coming from the engine.

It may be normal, but only because of engine wear and/or lack of maintenance. A properly maintained healthy engine with 30K on it should not be exhibiting this. Withe respect to Oblivion’s points, the rise in manifold pressure (plunge in vacuum) and the change in the throttle position sensor signal are both almost instantaneous when the pedal is pushed. These signals are processed in milliseconds by the ECU and the injector bandwidths are instantly changed to accomodate the new engine demand. With multiport injection the adjustment is almost instantaneous, taking effect on the next cylinders up. In days of old when accelerator pumps pushed extra gas into the venturi in an almost uncontrolled manner I would have agreed with Oblivion, but not on modern engines.

When was your friend’s last tuneup? Weak ignition components, bad plugs, these types of things can cause inadequate combustion and black smoke, and often do. Something in the engine’s history could have caused inappropriate wear of the valve stem seals, and that could draw a bit of oil into the chambers on high vacuum conditions.

I can’t get a hold of him but he did tell me that a few weeks ago he brought it in because his dashboard had a crack and water got into the car when he was away. They had to replace the dash but they said all the electronics were fine. Do you think the water getting into the car would have any effect on the engine?

Not likely. If water had damaged the electronics that would be affiliated with this problem he’d have serious operating problems.

Honestly, my guess is that he’s overdue on a good thorough tuneup. As I mentioned, black smoke is carbon from incomplete combustion. That comes from too rich a mix or a weak combustion process (explosion). Weak ignition components, such as plugs, wires, etc., have an effect of weakening the explosion. A good, hot, instant spark that immediately begins the chain reaction is necessary for the gas to fully burn in the extremely limited time it has during the power stroke.

The next places I’d look if a good tuneup doesn’t help is to the sensors, starting with the upstream oxygen sensor and perhaps even the mass airflow sensor. But you’ll need someone with some expertise to check this stuff.