VAG 5-Cylinder TDI: Excessive Smoke?

hello,

I'm new here and hoping to get some tips. I have a V70 with 200,000 km and a 5-cylinder engine, which uses the older Audi engine. It seems like the previous owner had it tuned (I'm not sure how).
The engine is running really well, and it's also very powerful.

"Just now, the mass airflow sensor was leaking. It was sealed and recalibrated by the Bosch service technician (in the car). Afterwards, I experienced slight jerking at idle (only when moving). It was adjusted twice more, and the torque was reduced from approximately 420 Nm to below 400 Nm. The car is not as powerful now, but it runs better."

Okay, but now I have the problem that the car is producing a lot of smoke. Especially when the engine is running below 1800 rpm.


The problem is that the workshops are hesitant to do much because of the modifications that have been made.

Okay, here are my questions:

"Can anyone tell me why I'm still experiencing a slight vibration when rolling to a stop with the coupling disengaged (it doesn't happen all the time, only very rarely)?"
"Can anyone tell me how the humming sound at full throttle in 4th or 5th gear, at only about 2000 rpm, might be related to the magnetic valve for boost pressure limitation?"
"Can anyone give me some tips on how to find the source of the soot? I read something about disconnecting and plugging certain vacuum valves to test things... but without a more detailed explanation."

I would be very grateful for any tips!

Greetings, Uwe.

hello,

It seems to be getting worse and worse. Can anyone please give me some advice? Please!


Thank you, Uwe.

How about observations of boost pressure in the soot range? Do you have any information on that? What engine code are we talking about? Is it possible to revert the tuning and then compare the soot levels?

questions upon questions...

Okay, I'd start by checking if the boost pressure and air mass are within the normal range under full load.

I don't know to what extent the problem with sealing the quantity setting device is related. Contact the Bosch service for information and post it.
For example, whether they removed the pump, etc.
Are you sure that the stuttering wasn't already present before?

hello,

"The fuel injection system wasn't adjusted, and the engine has been misfiring for a while. However, it's not really related to the soot issue. In fact, the misfiring disappeared after replacing a solenoid valve for the exhaust gas recirculation system!"

What I'm noticing is the soot buildup in the lower RPM range, and especially when the turbo kicks in.

"Shouldn't the Bosch service be able to check the fuel pressure and air mass?"

thank you for the help.

Greetings, Uwe.