Ladedruckanhebung ACV per SMD | Posts 16+

Yes, the engine control unit number was read out using VAG COM, and yes, it is an ACV. However, I am currently unable to access the engine control unit with my new laptop (see thread: PCMCIA Serial Adapter), so I unfortunately cannot tell you the software version.

Regards, Peter.

Hello!

I recently installed a boost gauge from Racimex and discovered that the boost pressure remains within acceptable limits. When accelerating, the T4 engine with ACV consistently reaches a boost pressure of 0.7 bar. There are occasional spikes up to 0.75 bar, and on the highway while climbing uphill at full throttle, the boost pressure remains constant at 0.75 bar.

Isn't that a little low? I'm going to check the target data list, but there definitely seems to be some room for improvement, maybe 0.1 to 0.2 bar more.

Hi everyone,

Peter.

Target data: 1700...1950 mBar. So, it could potentially go even higher. It should be noted that this T4 has different software in the engine control unit (ECU), which means there's a quantity adjustment feature. Unfortunately, this can lead to some soot production at full load. By slightly increasing the pressure, I hope to reduce soot emissions and achieve a slight increase in performance.

Greetings to you all,

Peter.

It seems like no one has any tips or suggestions on this topic. I have one more question: Which pins should the potentiometer be connected to?

Hi Peter,

/viewtopic.php?t=3232&highlight=pin assignment + pressure sensor
/viewtopic.php?t=562&highlight=pin assignment + pressure sensor

Thank you very much! I knew there was something about that, but apparently I overlooked it because of the title. Thanks again.

I will report.

Hello!

Today, I was standing in front of the car and realized, "Man, you're a technological disaster."

It started with the shopping process. Linear potentiometer or logarithmic potentiometer? (hopefully I spelled that correctly). What difference would that make for my project?

In the description for the electronic boost pressure gauge, the potentiometer is connected to a fixed voltage supply. I understand that the wiper arm is adjusted precisely to the point where the desired voltage is located between the positive and negative terminals (to put it simply). The actual voltage is taken from the wiper arm. One side is grounded, and the other is +5V.

What resistance (in Ohms) should the potentiometer have to achieve a maximum increase in boost pressure of no more than 0.3 bar? Unfortunately, I don't know what type of sensor is installed in my vehicle.

Should I now change the supply voltage of the sensor (as described in the instructions), or the output signal? So, connect the slider to the control unit, and the ground and output signal to the outer contacts?

Since I want to prevent any kind of damage, I'd rather ask a silly question three times than once not enough. I hope the technically competent members don't take offense at such questions.

Greetings to you all.

Peter.

Hello everyone!

Since no one else has commented on my attempt, I'll simply share my experiences.

I used the potentiometer to adjust the supply voltage.

Result:

After attempting to slightly reduce the voltage using the potentiometer (by approximately 1 to a maximum of 2 volts), this resulted in a temporary increase in boost pressure (from 0.75 to 0.85), which immediately returned to the original value. Now, the question is: who exactly is controlling it?

If you reduce the supply voltage even further, the whole system will end up in emergency mode, which is annoying.

If I were to connect a potentiometer to the output signal, how would the control unit behave? Unfortunately, I'm not entirely clear on Ohm's Law, but could it potentially cause problems?

I will make further attempts and report back.


Hi everyone,
Peter.

Over 1300 views on this post, but no one can offer a suggestion as to why?

Hi.

The boost pressure sensor can only supply a very small output current (less than 10mA).

Probably no one is saying anything because nobody wants to take the blame for your damaged loader.

What you're planning to do is quite a tricky undertaking, especially if calculating a voltage divider seems difficult for you. No offense intended, but who wants to be blamed for your motor breaking?
Operating the diode in forward bias might be more sensible because if you accidentally hit the wrong limit with the potentiometer while driving, it could quickly cause a surge that could damage your equipment and cost you a lot of money.

Best regards, Rainer.

Hello Rainer!

First of all, thank you for your reply. I understand that this is not entirely a safe thing to do. I'm not going to be wildly adjusting the potentiometer. There's a boost pressure gauge for monitoring, and everything will be checked ten times before the engine is started.

So, I'm approaching this with the utmost caution, which is why I often ask questions. After all, I don't want to make a mistake that someone else might have already made before me.

Hmm, the diode solution sounds good, but I'm not really knowledgeable in electronics. I'm okay with traditional electrical work, but unfortunately, not with electronics.

Let's try using the diode now (I know its forward voltage is -0.7V).


Hi Peter,

Hi,

The 0.7V voltage drop across the diode only applies starting from a certain current level.

Since only a few milliamperes are flowing through the diode in your case, you should expect a voltage drop of approximately 0.2 to 0.5 volts.

Best regards, Rainer.

Hello Rainer!

"You had the best tip of the day with the diode. Since you mentioned that in this case, a maximum voltage drop of 0.5V can be expected, I quickly tried it out. I don't want to achieve extremely high charging pressures, but just slightly increase them. Therefore, 0.5 volts seemed perfect."

With the addition of a diode, my ACV now achieves a mechanically measured boost pressure of 0.8 bar (peak value 0.85 bar). This represents an increase of exactly 0.1 bar compared to the initial value.
(Target values: 0.72...0.92 bar)

Exactly what I wanted. The black smoke during acceleration is no longer visible once the maximum boost pressure is reached, and it also pulls a bit better (previously, with different software on the ECU).

So, I achieved my goal thanks to your advice. I'm also quite certain that no damage is expected.

Thank you and best regards, Peter.

Great .

A friend of mine, who is a trained electronics engineer, is currently designing a circuit for me using an operational amplifier and a voltage divider in the output stage. This should be a more adjustable and professional solution. I will report on the results; please just be patient. Ideally, I would also like a safety circuit that immediately reduces the charging pressure if it exceeds a certain value. We could use the original sensor for this.

Regards, Peter.

Here's how the circuit diagram should look.