1.9 TDI BLS: Boost Surge Explained

Hello everyone,
My TDI, which now has 185,000 km, occasionally experiences overboosts. These occur in conjunction with the regeneration process (at least the mileage readings seem to correlate). This also happens on level ground while driving with cruise control, with intervals of approximately 2,000 to 10,000 km.

The basic alignment looks good, there's no noticeable jerking during adjustment, and it was also fine when checked with a syringe. However, there are detectable overshoots in the log data. What do you think about this? Is it still within the normal range, or is it already too much?

Here's a Screenshot showing the comparison of solar radiation levels, along with a log file containing data from MWB 3.8.11.

Thank you in advance for your support.
VG

It would be helpful if you first created a proper log file and read the relevant article about it.

If it mainly occurs during regeneration, the VTG (variable turbine geometry) is likely to seize up in very hot conditions (search: "hot seize").

Best regards, Rainer.

Quote:

The VTG (Valve Timing Gear) is likely to stick slightly in very hot conditions (search: hot sticking).

... which, given the mileage, is no longer entirely out of the question .

Hello everyone,
Thank you for the feedback.
I will provide a short log with the specified operating parameters and workload as soon as possible.

Otherwise, I found an article from someone with a BLS engine that exhibits similar behavior to mine, with a very extreme torque increase, which could also indicate an incorrect charging system setting (which would surprise me, as I bought the car with 60,000 km on it), but I will also check that.

Otherwise, I think you're probably right. If that's the case, would simply disassembling and cleaning it be enough? Usually, that's only described as a temporary solution. Otherwise, what could be the cause of the damage? I don't want to ruin a loader that I might install later.

I also plan to empty the DPF when the weather is better; it's currently at 48g (out of 60g). The lower exhaust backpressure might slightly reduce the temperature of the catalytic converter. I may also log the differential pressure values to monitor this.

VG