TDI Engine: Intermittent RPM Fluctuations BLS 77kW

Hello Diesel Enthusiasts.

I'm new to this forum , but I've always read posts here.
It's a really great forum. Keep up the good work.

Now I'm also experiencing a problem with my Skoda, which has a 1.9 TDI PD engine (engine code: BLS) and a 6-speed DSG transmission (LQS).

It occasionally happens that when I'm driving the Skoda, I feel a jerking sensation from the engine . It's as if the engine is losing power and then accelerating again . This is also noticeable on the tachometer, which fluctuates up and down, and as I mentioned, you can feel it while driving.

Then, for 2-3 weeks, I don't experience the problem at all, and the engine runs normally.

I've now taken my Skoda to two different authorized service centers.
But unfortunately, the problem was not found .

There are no errors stored in the engine control unit.
One garage added an additive to my fuel tank to clean the EGR valve, but that didn't achieve the desired result either.

And the other garage also checked the error memory, but they didn't find any errors in the engine control unit either.
They then suggested that it might also be due to the mechatronics of the DSG transmission. However, I don't want to replace that mechatronics unit yet because it's quite expensive.

By the way, the engine has a mileage of 192,000 kilometers.
Now, I hope one of you has another idea or tip about what it could be , and as mentioned, the problem occurs sporadically.

Thank you for your tips and assistance.
Best regards, Snaker.

Hi,

How often does the error occur? If the logging process stops prematurely while recording data from the engine control unit (ECU), there might be a problem with the power supply to the ECU.

Faults caused by defective fuses or damaged fuse boxes can also affect the engine control unit, so it's important to thoroughly check everything in this area.

Best regards, Rainer.

Hello, diesel mechanics.

Thank you for your contribution.

Unfortunately, I can't say how often the problem occurs. Yesterday, while driving home in the car, the engine started making that sputtering noise again, and the tachometer fluctuated slightly. And it felt like the engine itself was giving gas and then taking it away.
Today, the engine was running really well again. It might take another 2-3 weeks before the problem reappears.

Was the cruise control active?
If that's the case, you can ignore the behavior.

Of our three more recent TDIs, all of them did. The Touran - also with...
BLS engine - more frequent (about every two weeks) than the Polo; the Octavia was in between.
Total mileage, including defects: >400,000 km.

One could speculate that the frequency increases with more weight per horsepower.

Best regards,
Micha

Hello Wiesel.
Thank you very much for your contribution .
Yes, exactly, the cruise control was active in each case.
I'm glad now that there's someone else who has experienced this problem. Was there someone who could tell you why the cruise control is responsible for the problem?

Yes and no.
It appears that the standard algorithm encounters issues under certain boundary conditions.
(To experience over-boosting due to factors like engine speed, temperature, fuel injection amount, load, etc.).
Interestingly, VW also had a similar (faulty) regulator in the EDC16 control unit used in the BLS engine.
parameterized, similar to the much older EDC15 used in the BLT.
The error is independent of the injection technology used (distributor injection pump vs. pump-nozzle system).

Best regards,
Micha

Hello Wiesel.
Thank you very much for the information .
Now, I'm at least a little more informed about the issue.
Is there no solution ?
Do we now have to live with this problem with this engine?
No one was able to provide an explanation .

Greetings.
Snaker.

The last software update for these engines was likely around 2008.
This "quirk" has likely been present in the software for at least 10 years.
Nothing will be changed .