White smoke on startup: What it means?

...I'm starting a new thread again, hoping for some help!

'For the past 44,000 kilometers, I've mostly experienced a white smoke cloud after every start, whether the engine is warm or cold. It's usually more noticeable when the engine is cold. This is on a Ibiza 6k, with an AFN engine and 363,500 kilometers.'

At 319,000 km, a different pump was installed, and the problem has persisted since then. That's why I suspect the pump, but I'm not sure what else could be causing it.

'Injection start is slightly below the optimum according to VAG specifications. The injectors were replaced at 300,000 km, as well as the crankshaft pulley bolts. It starts on the first try, and there are absolutely no noticeable issues, no error codes in the memory, and no loss of power, oil, or unusual water consumption. The cylinder head gasket and timing belt have also been replaced previously.'

It must be related to the fuel pump somehow, since the problem only started after I replaced it. The old one had a stuck injector nozzle. The replacement pump came from a '99 G3 convertible, also with an AFN engine, and has the same part number!

What else can I check regarding the pump?

P.S. If the vehicle is going downhill, the cloud is noticeably larger, which is very strange!

Has anyone else ever experienced a similar problem?

Hi,

Have you already checked the static injection timing, for example using the TDI Timing Checker from VAG-COM?

Best regards, Rainer.

Okay... VAG (Volkswagen Audi Group) settings --- Basic settings --- TDI timing is slightly below the target line, indicating it's 'a little' late! Normally, in the measurement block, the injection quantity adjuster shows a value of 53.8%, so not much correction is being applied.

Could a lack of compression in one cylinder potentially cause this? One of the cylinders has a very straight ridge on its bore, but it's been there for some time.

It starts perfectly fine... and what surprises me is that the steam cloud is immediately visible right from the start. And this thing about it going up and down is quite curious, almost as if something is leaking or dripping in somewhere!

Yes, it's possible that a cylinder has slightly less compression, which can cause some smoke. White smoke is usually unburned fuel.

Perhaps a nozzle is leaking; that's not unlikely given the mileage.

However, the injectors have only been used for 60,000 km...

Hello,

White smoke can also be caused by oil vaporizing in the crankcase. Could it be that the valve stems are slightly leaky on the exhaust side, causing oil to seep into the crankcase while the engine is stationary?
Sure, I can translate the text from German to English and explain why the phenomenon is location-dependent. Please provide the text you would like me to translate.

Regards,

Hopel.

I had also suspected something like that, but are the exhaust gases hot enough to directly burn the oil during startup? And the smoke is white, which wouldn't be typical for burning oil, as that would usually be blue!

The injectors are fine; I've already had them checked for leaks before.

I'm going to try and record a video of the launch!

http://www.myvideo.de/watch/4027664

This morning, I took a video of the start, but unfortunately, it was quite windy, although you can clearly see the smoke dispersing! Yesterday, I didn't drive much, so the cloud is a bit smaller; otherwise, there's usually significantly more fog .

Hello,

The oil vaporizes because the temperature in the exhaust system isn't hot enough yet, which is why the smoke is white.
However, this doesn't align with your statement that it only produces a little smoke because you drove very little the day before. If it's the piston rings, it should actually produce more smoke.
To me, that smoke looks more like water.
If you've ever seen a model train with a smoking chimney, that's what evaporating oil looks like.

Regards,

Hopel.

'...yes, that's it. Sometimes there's no smoke at all, sometimes just a little bit, and sometimes a really thick cloud of smoke, depending on whether I'm going downhill or uphill! Even if it's been running hot, the cloud will still be there after standing for 10 minutes!'

I had already removed the head, and everything seemed to be in order with the gasket, but I'm ruling out water because it first appeared immediately after replacing the pump!

Good evening.

I'm reviving this thread because my AFN engine in a Passat 3B is doing the exact same thing. There's a short burst of white smoke on startup when the car has been sitting for a while. The engine runs normally, and starting is fine. There's no water or oil consumption; it's around 0.5 liters per 15,000 km. The engine has currently 322,000 km (approximately 200,000 miles) on it, everything is original, including the injectors. Does anyone have any ideas what it could be? This thread seems to have remained unresolved...

Regards,
Ronny.