Boost Pressure: Vacuum Leaks in Charge Air Hose?

Hello TDI enthusiasts!


I read in a report that it might be possible to slightly increase the boost pressure by making small holes in the pressure sensor hose leading to the control unit.
Does anyone have more information about this?

I personally drive an A4 1.9 TDI with an AHU engine, AFN injectors, and a switchable Princiotta system.
The PowerBox supposedly delivers around 125-130 horsepower, although this is not an officially measured value.


Report on AFN injectors in an AHU 90hp engine for those interested:

Since I installed the larger injectors, my car only smokes about half as much as it did before, for some reason, and with noticeably more power. Then I turned on the power box, and it really takes off!
'No issues have arisen regarding engine performance or power delivery. The total cost so far has been only €179, which includes €100 for the nozzles from eBay and €79 for the control unit, also purchased from eBay a year ago.'

Have fun!

Hi there!

Let the "Löcher" (holes) tickle!

What you're likely to get is a 00575 error code and a limp-home mode.

These are measured, but never actually felt, 60 horsepower })).

Then it's better to manipulate the sensor in the engine control unit (ECU) with a resistor -> 10 CT tuning for boost pressure (technical article).

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

... or better yet, just put the box in front of the tires and drive over it .
Then, adjust the engine control unit to match the injectors and set the boost pressure.
lift it up.

Best regards, Rudi.

The latter is probably the better option!

Jut jut ! Topic closed!!!

Have fun!

dieselmartin wrote:

What you're likely to get is a 00575 error code and a limp-home mode. ... Then it's better to manipulate the sensor in the engine control unit (ECU) with a resistor -> 10 CT tuning for boost pressure (technical article).

Hmm, why would the engine control unit (ECU) throw a 575 error? It's simply receiving a lower boost pressure reading, just like if you were to solder a resistor onto the sensor. The advantage of using holes would be that you wouldn't reach the measurement limit of the sensor, which might happen with a resistor-based solution.
Sure, the best solution would be to customize the software, but that shouldn't necessarily yield significantly better results; it would just allow you to read the correct values using VAGCom.

/Jan

And what about the boost pressure that whistles out through the holes? It's all a vicious cycle. I drill holes to let boost pressure escape, so that less pressure is applied to the sensor, so that the turbocharger is controlled more aggressively to generate more boost pressure .

P.S.: 3 instances of the word 'damit' in a sentence -> Best regards to my former German teacher.

Hi Jan,

Here's how it will proceed:

A little bit of stinging.
-> no change (especially since you don't even notice the increase in LDD!!!)

2. It's not enough for him.
-> more poking

At some point, the engine has been modified so much that the stock ECU reaches its limits regarding what it can control with the N75 valve on the wastegate.

If she doesn't notice it, things could get even worse as the turbo spins faster and faster because the EDC is allowing the wastegate to open.

Then you don't have a genuine 575, but rather a turbo that has been damaged or modified.

"Loecher pieksen" is simply too imprecise to measure accurately, especially since they can react differently under varying pressures.

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

The advantage – even when manipulating resistance within the engine control unit (ECU) – is that defined conditions prevail.
The behavior of the holes depends on factors such as dirt, temperature, and changes in the material of the hose.

Best regards, Rudi.

:edit: Hi Martin, you were faster .

Hello.

Simply increasing the boost pressure alone cannot generate more power. Furthermore, if you don't increase the fuel supply accordingly, for example by using larger injectors (like 216s), it will negatively affect exhaust emissions and engine performance, leading to issues like rough running and excessive soot production!

What I was wondering about the erasers is whether it might be possible to reduce soot emissions during sudden load changes, starting, and full throttle by slightly increasing the pressure, without installing a diesel particulate filter or making expensive adjustments to the engine control unit!

Sorry, but "screw emissions."

Have you ever ridden in a modern TDI or CDI vehicle?

They puff out smoke like a broken Golf 2 naturally aspirated diesel when the guy in front briefly lifts his right foot off the accelerator.

Probably, they are already running with such low nitrogen content under normal operation that you can add a significant amount of diesel for a load change, and the overall turbidity will still be within the acceptable range.

I can't explain any other way why my 1Z, which is very low in inductance (but also has high resistance), accelerates (something I was able to counteract by using a 500 Ohm resistor )).

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

If it occurs in certain driving situations, this behavior will be indicated by a...
improve the airflow (which you can achieve by increasing the boost pressure, even through holes).
The holes, however, don't create anything reproducible.

So, if you're hesitant about getting a chip tuning done, and you want to do something anyway, then...
at least take the path of resistance within the control unit.

You're unlikely to solve the jerky behavior issues with just more airflow.
Do you also experience the jerking issues without the box? My 1Z engine has .216 injectors installed, and it runs smoothly.

Best regards, Rudi.

Okay, I'm going to try it with the holes. When you read what some people are doing in the chip tuning forum, you have to be careful who you let work on your car. Sorry if I offend anyone here, but there are some people who don't know what they're doing and sell that stuff for a lot of money (Of course, there are also many people with extensive knowledge).
I won't be drilling holes in the hose; instead, I'll attach a metal tube to a T-piece between them. Additionally, I will also place a constriction upstream of the T-piece in the hose. The whole thing should function similarly to a voltage divider in the electrical field. Of course, it is still temperature-dependent, but let's see. I will report back if the turbo fails.

I've also installed AFN nozzles in my 1Z engine, and with a 10-cent gap, it works quite well, but I'm leaving a lot of people completely baffled behind me.

/Jan

Hi Jan,

The "Löcher affair" reminds me a bit of the often-present misunderstanding between voltage and current.

In my opinion, these holes are not suitable for creating a pressure drop, but rather allow a certain volume of fluid to pass through.

A pressurized hose can maintain a pressure of approximately 1 bar for quite some time without needing to be refilled. However, even a small hole will cause it to lose all its pressure if not regularly replenished.

However, if there is a supply of air, the hole will only cause a partial pressure drop.

"So, your boost pressure change depends on the volumetric flow rate, which is actually not what you want."

A resistor whose size can be easily adjusted using the sensor when the engine is idling, in conjunction with an external pressure sensor, provides a much cleaner and more controllable solution.

Simply adjust the resistance so that the boost pressure sensor displays, for example, 100 mbar less than the ambient pressure (when the engine is stationary) – and you'll have 0.1 bar more pressure, assuming a linear characteristic curve.

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

dieselmartin wrote:

However, if there is a supply of air, the hole will only cause a partial pressure drop. "So, your boost pressure change depends on the volumetric flow rate, which is actually not what you want."

It's essentially the same principle as in electrical circuits, except that the pressure drop doesn't depend linearly on the input pressure. A voltage divider also requires a certain amount of "leakage" current.
The important thing is that both the back pressure and the hose resistance, or any built-in throttling mechanism, remain constant, which would not be the case if holes were drilled.

Why shouldn't the pressure drop be linearly dependent on the inlet pressure? It should be almost exactly analogous to electrical circuits (if we ignore minor effects). The volumetric flow rate would be equal due to the hose resistance and the discharge resistance, and the pressure drop would be proportional to the size of the resistance. With an increased inlet pressure, this ratio should remain constant, otherwise the volumetric flow rate through both resistances cannot be equal. This means that you should be able to reduce the pressure in a constant proportion, regardless of the inlet pressure.
Since I have a 1994 1Z engine, the 1 bar pressure sensor is likely located in the control unit (ECU), and I won't be able to increase the pressure much by soldering (even with chip tuning, there probably isn't much that can be done). As reported, I am already experiencing overboosts up to 1.1 bar. My only option then is the solution involving drilling holes in the hoses.

/Jan