Wave-like acceleration with Box?!

Hello!

'For some time now, I've been having problems with my power box. Every time I activate it (switch), the car accelerates in a 'wavy' pattern. That is, a smooth acceleration is no longer possible. The car does get faster, but only with increased smoke output and that peculiar acceleration behavior. When the box is not connected, everything is fine. Now, about the box: I bought it from eBay about a year ago and was satisfied with it until now. It has two adjustment screws.' According to the instructions, one knob allows you to adjust the fuel injection amount at idle, and the other allows you to adjust the power output (turn it while the engine is idling until you notice an increase in RPM, then turn it back one notch).
Where does this wave-like acceleration come from? I'm really at a loss and I'm almost too afraid to activate the device anymore.
Who can help me???
Thank you.

P.S.: My car is a Volkswagen Vento TDI with engine code 1Z, and it has 118,000 km on the odometer.

Hi.

Occasionally, the mass airflow sensor (MAF) may be responsible for generating pulsating forces (likely due to an output signal that is delayed relative to the airflow, in conjunction with boost pressure control processes).

I have also observed similar phenomena when "cleaning" my VTG (variable geometry turbine) using a rectangular wave generator at the magnetic valve while the vehicle is in motion. However, the fluctuating boost pressure gauge immediately reveals the source of the strange behavior.

If your engine is also producing a lot of black smoke, I suspect the turbocharger might be set too aggressively. This could be causing rhythmic "limp home" modes with reduced fuel injection due to excessive boost pressure. Once the boost pressure is back within the normal range, the emergency mode is deactivated, and the process begins again.
I would suggest turning down the boost a bit – and in my opinion, this would increase the chances of the engine having a significant amount of remaining lifespan.

Based on reports in some forums, it seems that excessive soot emissions and frequent operation at full load often lead to engine damage relatively quickly.

Hello Ulf!
I removed the LMM (likely referring to a mass airflow sensor). There's no dirt in it. Also, I completely reset the control unit and then reconfigured it. Now it's running with the 'normal' settings. So, not cranked up.
As a result, the wave-like acceleration has improved somewhat. However, it is still noticeable. Damn it.
I think I'm going to sell this thing and buy a brand-name device (like an Authal, HOPA, or ALpin, or something similar).

Do you have any other suggestions for things I could do?

Thank you.

Oh, I also had the AGR (Abgasrückführung - Exhaust Gas Recirculation) deactivated. Could it be related to that? 'However, I've already driven 1000 km with the EGR system deactivated and haven't noticed anything.'

Hi.

Quote:

Do you have any other suggestions for what else I could do??

As I said, it could also potentially be due to a faulty lambda sensor. If you could try a different (working) one, that would bring clarity to this issue.