Chip Tuning: Understand Engine Optimization

Hello everyone,

I hope it's okay to start threads like this here.
I often browse here and appreciate the extensive database of technical articles; it has helped me in many ways. I would like to try to better understand how my AJM works, or which parameters influence its performance. I repeatedly encounter technical terms that are difficult for me, as a non-expert, to properly classify. Perhaps someone would be willing to explain my questions to me; I would really appreciate it .

Perhaps a brief overview of my car's specifications:
It's a Volkswagen Golf IV with engine code AJM and gearbox code DRW. The car has 195,000 kilometers (approximately 121,000 miles) on the odometer, has a standard power output of 85 kW (114 hp), and produces 285 Nm (209 lb-ft) of torque.

In 2009, I got my first chip tuning through "Vitamin B" (if you do this, I can do it for you - okay). It came with a chip file from xxxxxxx. It was a complete mess, and the car smoked like crazy. I didn't drive it like that for long; instead, I went to XXX and got a tuning done the way I wanted. After VW replaced the head gasket (AJM issue, unfortunately) and the turbocharger earlier this year, they had the capability to update my engine control unit. That's why I visited Dirk again and had the car chipped again.

With the first tuning of the XXX, I also had it tested on a dynamometer, which resulted in 147 horsepower and 370 Nm of torque. The second tuning feels similar, but performs better at lower RPMs. However, I haven't had it tested on a dynamometer yet, so these are subjective values.
When reading articles about engine management, I often come across terms like soot reduction (sometimes also called "smudging") or torque limitation. I can easily understand "driver demand" – it's simply what my foot applies to the accelerator pedal. However, I don't quite understand the concept of "smudging." Let's say I want to overtake and press the accelerator fully. In that case, is there a maximum fuel injection value programmed for each cylinder that is initially injected, and then only adjusted based on the amount of air available, which passes through the mass airflow sensor (MAF)? Or how should a layman understand this process?
And how is this "cloudiness" measured? Or are values provided to the control unit that are assumed to be appropriate?

Based on an article I read, I installed the intake air duct from a DSG R32. If this has resulted in increased power, it's likely only measurable, as I haven't felt any difference subjectively. However, my friend, who often drives behind me, said that since I installed the air duct, he notices less soot. He still sees a puff of smoke when I accelerate hard, and then there's a slight amount of smoke afterward. I can only see it at night, for example, when I'm stopped at a traffic light in second or third gear and accelerating quickly; in the headlights of the car behind me, I can see a faint trail of smoke on the road. Otherwise, I don't notice anything in my mirrors. Can I actively influence the amount of diesel injected per cylinder until a maximum value X is reached, by improving the intake air flow or improving the airflow to the intercooler?

If I understand correctly, the values for opacity (soot level), driver request, and torque limitation are crucial for the calculation. The lowest value is used as a reference point for determining the amount of diesel additive to be added. Is that correct? So, if I, as the driver, want 60 mg, but the opacity reading is 50 mg and the torque limitation is 45 mg, then will 45 mg be added?

I know that some of you experts might be slapping yourselves on the head when it comes to these questions, but for me, it's interesting to understand what's going on, and I try to grasp it as well as possible and find such things simply fascinating. Maybe someone will take pity on me and tell me that my theoretical understanding is good enough, or maybe they'll tell me that I haven't understood anything correctly yet.

I hope you all have a wonderful Easter holiday!

Quote:

Is the lowest value used as a reference point for adding the diesel fuel? So, as a driver, I want to add 60 mg, but the turbidity is at 50 mg and the torque limitation is at 45 mg. Then, are these 45 mg taken and added?

Right, and specifically in that order (at least for Bosch/VAG systems).

Quote:

and only then is the mixture adjusted based on the amount of air available, which passes through the mass airflow sensor (MAF), or how should a layman understand this process?

The smoke map defines the maximum injection quantity that can be combusted without producing smoke at a given air mass (x) and engine speed (y).
In partial load operation, the driver's desired value will be the lowest, while torque and air mass limitation (throttling) will be higher. When you enter full load mode, the throttling will limit the amount of air until sufficient air mass enters the cylinders based on the boost pressure, and the air mass limitation (throttling) will be higher than the torque limitation.
Then the torque limit is again set to the lowest value, as it should be.

Thank you!

Quote:

In the smoke map, the maximum injection quantity that can be combusted without producing smoke is defined for a given air mass x and engine speed y.

Okay, so the value is fixed and cannot be influenced in any way without modifying the engine control unit, which is one of the approaches used in chip tuning.

Well, it seems I wasn't entirely wrong with my understanding . My compliments to the people who write all those technical articles; even laypeople can understand them quite well .