Boost pressure increase

Hello.

I performed the boost pressure increase modification on a 1.9 TDI AFN engine from 1998, following ULF's instructions.
The sensor signal is distorted by three diodes, resulting in a charging pressure of up to 1.4 bar.
to be at full load.

Unfortunately, the boost pressure spectrum hasn't just increased at the top end; it has also decreased at the bottom. This means that even with light acceleration, there is already a boost pressure of 0.5 bar.
What it would have been without the diode.

The problem manifests itself at constant speeds above 90 km/h.
The boost pressure doesn't drop below 0.4 bar anymore.
Is it very stressful for a VNT17 turbocharger to constantly build up 0.4 bar of boost pressure at a speed of 130 km/h?
Is that much pressure really necessary when driving at a constant speed?

My next thought would be to replace the diodes with a resistor.
A resistor would not have the same voltage drop in the low-voltage range as the diodes do.
Does anyone have another idea?

Please don't make fun of my statements with passive constructions; I know I don't understand ).

Best regards, Peter.

Hi there.

Could it be that you made a typo above?

Because you are contradicting yourself.

Quote:

but also reduced below

.

Quote:

The boost pressure doesn't drop below 0.4 bar anymore.

So, you're expecting a charging pressure of 0 bar at some point?

When driving, it only operates in the "cut-off" range; as soon as the engine needs to do something, it provides power.

With a boost achieved through diodes, it can naturally affect the entire pressure range instead of spreading it, but only increase it.

You probably wanted to drive with a pressure of 0.0 to 1.4 bar instead of the usual 0.0 to 0.9 bar, but now you have a pressure of 0.5 to 1.4 bar.

Klar, denn du hast nur die Kennlinie verschoben, da der Sensor nicht den relativen Druck misst, sondern den absoluten - d.h. du hast in deinem Regelspektrum keinen Nulldurchgang - so wie bei der Einspritzpumpe und 10 Ct. Tuning.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Hi,

What is the purpose of this whole exercise?

Increasing boost pressure alone has no effect on power and torque.

To provide meaningful suggestions, it would be very helpful to know what other aspects are different or how things are being manipulated.

Best regards,

Jan.

Use a rail-to-rail op amp and a trimmer at the output. This will give you a percentage gain, rather than an additive shift in the characteristic curve!
That works!
However, a few more components are needed!

@dieselmartin

exactly.

Do you have any ideas on how I can 'spread out' the spectrum?
Perhaps this is a bit easier than using a rail-to-rail op amp with a trimmer at the output.
I don't even know what kind of components these are .

Maybe it also works with a fixed resistor?

Thank you, Peter.

What is the point of all this exercise?

Increasing boost pressure alone has no effect on power and torque.

To provide meaningful suggestions, it would be very helpful to know what else is different or how things are being manipulated.

A 'tuning' module has been installed. (It's connected via a plug to the wiring harness between the control unit and the pump).
Due to the high Russian influence, the loader was modified using diodes and instructions from...
'Ulf was lifted up, but I omitted the voltage divider from the measurement input (V_Mess) to ground.'

The device can be turned on and off with a switch located in the cockpit.


Basically, the fact is that the entire range of boost pressure has been increased.
'That's perfectly fine, as the pressure builds up much faster. (It already reaches half a bar with just a slight press on the accelerator).'

'However, sometimes it really gets on my nerves when the TV is turned off (especially because of the engine).'
'It's frustrating when I have to drive uphill and the turbo kicks in.'
even though the air mass is already far above what is needed.
As I said, this also happens at speeds above 100 km/h.

I've now decided to also install a switch for increasing the boost pressure.

With a measurement voltage of 0-5V, a cable length of 4 meters (with a diameter of 0.22mm) should be used.
careless, or !?

Here's a visual representation of the idea.

http://members.aon.at/neubaupe/ladedruck_mit_schalter.gif

The only dumb thing about it is when it comes to races at traffic lights or something like that.
Do I need to operate two switches beforehand?

Best regards, Peter.

Then use a switch with two separate circuits (a double-pole switch).

neubaupe wrote:

With a measurement voltage of 0-5V, 4 meters of cable (0.22mm diameter) are required. careless, or !?

Basically, yes.
The current is very low, so there will be no significant voltage drop.

If a boost pressure indicator is present, there's generally nothing against using a potentiometer.
If I've correctly understood the datasheet for the Motorola 2.5 bar sensor, the output current is 0.1mA. I can hardly believe that it would only be 100µA. Therefore, a correspondingly high value should be used for the potentiometer.
Let me quickly do a calculation.
Maximum output voltage: 5 volts.
Maximum output current: 0.0001A; Voltage/Current = Resistance.
-> Internal resistance: 50 kΩ
->Poti sollte viel größer sein, um den Wert nicht zu sehr zu verfälschen. ViPossibly 1 Mohm?
Please correct me if I am wrong!

"0.1mA indicates that the output can only handle a load of up to 0.1mA; this means that it is guaranteed that the output voltage will remain stable up to that current level."
How do you plan to connect the potentiometer?

Okay, please provide the text you would like me to translate from German to English. I will only provide the translation.
That would be my suggestion. However, the limits should be restricted to a certain extent using fixed resistors, just as a precaution, see the details on the right.
Important: Monitor the LDA during adjustment.
http://imageshark.ath.cx/0815/6969239142a971598de79.JPG

I solved it myself using a rail-to-rail op-amp. And it works. That means the potentiometer is placed after the op-amp, and the op-amp acts as a current amplifier.

ps. My VNT15 already delivers a pressure of 0.4 bar at 130 km/h, possibly slightly above or below that. When going downhill, the pressure drops to 0.1 - 0.2 bar, and when going uphill, the maximum possible pressure is reached, depending on the incline.

edit:
@wolfi_b

If you are correct, then the output has a 'constant current source' of 0.1 mA.
Then you should disregard the calculation I provided earlier. In fact, this would only be beneficial because R(i) wouldn't need to be included.