Smokey A4

Honest John Back Room » Technical matters
View Threaded
Wed 19 Jul 2006 23:56
Smokey A4 - Roly93
In the past few days of hot weather, I've noticed that my A4 TDi 130 has been very smokey even on relatively mild acceleration.
I've cheked all the usual items, ie the fuel consumption is still very good at 50+, the air filter is definately not too bad and the fuel was Shell with a tankfull of BP from yesterday. Oil consumption is still negfligible, and performance is still perfect.
The car has had quite a few hundred miles of fairly hard motorway work, but still smokes a bit more than I would have expected.
What could be the cause ?
Could this in some way be attributable to the extreme temperatures we've been having, as I've been driving in 32+ degrees in the last 3 days.
Reply | Report as offensive | Link
Thu 20 Jul 2006 09:21
Smokey A4 - Railroad.
You need to establish the colour of the smoke.
Blue = Burning engine oil.
Black = Excess fuel

If it's blue then you may have an oil leak into the turbo, excess engine wear or breather problems. Check oil consumption.

If it's black you may have a hosing injector, clogged air filter, air intake leak, faulty turbo wastegate or even worn injection pump.
Reply | Report as offensive | Link
Thu 20 Jul 2006 09:58
Smokey A4 - Roly93
Its definately not oil smoke, and the oil consumption is fine.
The VaG diesels dont have a waste gate as they use variable nozzle turbos, I havent checked this, but the performance is otherwise fine.
Reply | Report as offensive | Link
Thu 20 Jul 2006 09:59
Smokey A4 - Roly93
I should point out at this stage that this is a 2 year old car with 35,000 miles.....
Reply | Report as offensive | Link
Thu 20 Jul 2006 10:44
Smokey A4 - Alec
I had blue and black smoke from my PD130 Passat.
I traced this to a loose intake pipe from the bottom of the intercooler to the tubular
crossmember.
The pipes have a quick-release mechanism so check they are all seated correctly.
Reply | Report as offensive | Link
Thu 20 Jul 2006 14:00
Smokey A4 - Roly93
The engine bay of the A4 is, as you would expect, a nightmare. However I ran the engine with the air filter disconnected, so when I put my hand over the inlet pipe the engine stopped and the vacuum in the system didn't leak out until I removed my hand.
This should prove that there are no induction leaks anywhere I think....
Reply | Report as offensive | Link
Thu 20 Jul 2006 15:10
Smokey A4 - Alec
That's an interesting test, but by creating a vacuum you pulled the pipes together rather than forcing them apart!!
In reality it may stll be valid.
Reply | Report as offensive | Link

We give you the low down on how to save on insurance, little-known tricks and tips, what insurance groups mean and how to use insurance aggregators to beat insurers.

Insurance group finder and how to save on insurance

Real MPG enables you to register the fuel economy you are actually getting against your make and model of car, its engine and type of transmission.

Every time you enter an average consumption figure against your car, the overall average automatically adjusts to reflect it.

Real MPG