Engine failure, cause? Audi 3.0TDI Engine: ASB

Hello,

as shown in the image, the pistons of cylinders 4-6
I have suffered greatly, and I can see the melting through the {WINDOW/GLASS}.
Fuel injectors, as well as almost all exhaust valves, are burned.

Cylinders 1-3 are not affected.

What could be the cause that only this cylinder bank is affected? All injectors are original and from the first series. (AB)

Is it possible to upload a picture from a smartphone?
If not, I will download them later, if necessary.

Quote:

Is it possible to upload a picture from a smartphone?

Yes, use the "Select File+" button.

[Translating...]

Drallklappen

Please explain the function of the {VALVE} in more detail.

Perhaps one of the cylinder heads didn't get enough combustion air, and is therefore overheating...

For each cylinder bank, there is a camshaft unit. In the servo motors, plastic gears are used, which will eventually experience tooth wear.
If the servo motor's position monitoring doesn't work, then the control valves remain closed even under high load, and the affected cylinders don't get enough air (because the filling channel is not open).

Due to the lack of air, the combustion process gets closer to the piston material, and the exhaust gas temperature also increases significantly. Since the other cylinder bank produces "healthy" exhaust gases and the earlier EU4 engines were not monitored as strictly, an error is usually not displayed until the engine is essentially dead.

EDIT: There is a characteristic parameter for the position of the control valves. Anyone who wants to eliminate the problem from the outset can have a competent chiptuner "adjust" the KF, which reduces the adjustment frequency and, consequently, the risk of failure.

That must be the exact cause, because the exhaust temperatures were so high that the cables in the area around the pre-catalyst melted, including the OT (Oxygen Sensor) connection, leaving only a lump.

Thank you very much!

Now I can finally sleep again.

Of course, this also means that the DPF probably needed to be regenerated more often, because somewhere the soot generated due to the lack of air has to go... and this also promotes high exhaust temperatures.

The 2.7/3.0 TDI engines already have air-gap-isolated (double-walled) manifolds. There shouldn't get *that* hot.... or does the melted connector sit at the back where the (intact) exhaust pipes lead to the turbocharger?

Exactly. The connector is attached to the gearbox bell housing. The throttle and exhaust pipe are located in this area. Even the Vorkat has strong initial colors.

Thank you again.

Can you upload the images, please?

Here are a few pictures.

Thank you for the pictures!

It seems like you were lucky and the cylinder walls didn't get damaged.
A little bit of polishing, new pistons, and it fits perfectly