Ladedruckanhebung ACV per SMD | Posts 32+

Hello!

Okay, I've tried everything now, and I was able to observe something peculiar.

"With the circuit described previously, it's easy to increase the boost pressure at full load. I stopped at 0.9 bar and drove a bit further (on the highway). However, suddenly, the boost pressure dropped to 0.5 bar, but there was no limp mode; the power was still there, although the boost pressure then readjusted itself to the usual 0.75 bar. On the next attempt, I increased it to a maximum of 0.85 bar, briefly lifted off the accelerator and then pressed back down, and what happened? The boost pressure went straight back to 0.75 bar."
I observed this phenomenon in both the diode circuit and the circuit with the operational amplifier.

Okay, here's my question: Does the ACV still have a master sensor that adjusts or fine-tunes the boost pressure, so that I ultimately always end up with the same value?
I know that the ACVs can be pressurized up to a boost pressure of 1.1 bar. For me, that's a value that is quite concerning.

Since there are also some electronics experts writing in this forum, I'm curious to know if anyone has taken the trouble to analyze the boost pressure sensor using an oscilloscope. What exactly does it show?

Okay, now I really want to know, that's why my curiosity.


Good evening.

Peter.

P.S.: The error memory will be read on Monday, because the Profiset is still with the post office .

Hi,

The boost pressure sensor outputs an analog DC voltage that varies depending on the pressure. The operational amplifier in the circuit only ensures that the output of the boost pressure signal from the sensor is not electrically loaded (the input impedance of an operational amplifier is very high).

Theoretisch könnte das Motorsteuergerät den 'Beschiß' bemerken, indem es Ladedruck und Luftmassenwerte auf Plausibilität prüft. Obs so ist? KeinI have no idea...

Best regards, Rainer.

Today, out of sheer curiosity, I tried the new adapter cable and immediately checked the boost pressure. What happens when I adjust my setup?

The boost pressure (reading on page 10, field three, hopefully the correct value) can be slowly reduced to approximately 320 mbar. If you turn it further, the value suddenly jumps back to the initial value. I did this with caution while the engine was not running. This then results in a short circuit to ground being stored in the error memory. But why do I then see the original value, i.e., my 0.75 bar, on my boost pressure gauge after a certain amount of driving? I will conduct a test drive and log everything to get a professional opinion from you. Of course, all with caution. Could it be that the boost pressure control valve plays a role here?

Greetings to you all.

Peter.

Hi, logging won't be much help, because then you would also have to log your analog display instrument .
Of course, the engine control unit has no knowledge of the actual boost pressure; that's the trick.
It's also possible that the mechanical mechanism simply reaches its limit or something gets stuck.

Best regards, Rainer.

Okay, I already knew that. I just wanted to see what my measure actually achieves.

Regards, Peter.

It all ends with the search for the lost boost pressure...

see here/viewtopic.php?p=41250#41250

It all ended with uploading new software to the engine control unit. The smoking issue is gone, and the boost pressure is now around 0.95 bar. So everything is fine.

Thank you very much for your help.

Peter.