Powerbox DIY: Optimize Energy Consumption

First of all, I would like to commend the very informative technical articles about 10ct tuning and power boxes. Especially because they also describe the biggest disadvantages of common methods: they only cause a static alteration of the sensor signals. The engine speed, which is an important criterion, remains unconsidered.

Here's a key sentence that prompted me to think about more intelligent signal spoofing techniques regarding injection timing and fuel consumption optimization:

'To reduce the amount of nitrogen oxides in the exhaust, the injection starts slightly later than it would need to be for developing full power. This increases the formation of hydrocarbons and particles. The fuel consumption increases by about 4% due to the later injection timing.'

(from: 'VW 1.9L TDI Industrial Engine')

Eine statische Verfälschung des NBF-Signals durch 10ct-Tuning (Widerstand + Kondensator parallel) hat zur Folge, daß die beabsichtigte Frühverlegung des Spritzbeginns nur bei einer bestimmten Drehzahl erfolgt. Bei geringeren Drehzahlen ist die Frühverlegung geringer, bei höheren Drehzahlen höher als beabsichtigt. In letzterem Fall können schädliche Spitzendrücke und Mehrverbrauch auftreten. Setzt man die beabsichtigte Frühverlegung auf die Abregeldrehzahl an, so ist die Maßnahme im unteren und mittleren Drehzahlbereich praktisch wirkungslos. Ein Dilemma.

Problem: A monostable flip-flop circuit delays the falling edge of a pulse by a fixed amount of time. In this case, the time-determining element is a capacitor that is charged up to a certain value.
However, a fixed time delay for the lag results in the angle-of-rotation-dependent early shift becoming increasingly larger as the rotational speed increases, because the NBF signal period becomes shorter in time, while the signal delay remains constant in time.

Requirement: The signal delay should not be based on a fixed time value, but rather on a fixed duration of the NBF signal period (which corresponds to the KW rotation angle).

Solution: Capacitance diodes are used as capacitors in the monostable flip-flop circuit, which change their capacitance depending on the applied DC voltage (higher bias voltage -> lower capacitance). The decoupling to the flip-flop circuit is done via a relatively large coupling capacitor.

The DC voltage, which increases proportionally to the speed, is derived from the frequency of the NBF signal by shaping the pulses to a constant amplitude and duration, and then integrating them (low-pass filtering).

This control of the varactor diodes is possible because the frequency ranges of the control voltage and the NBF signal are very different. The maximum frequency of the control voltage should not exceed 1 Hz (for rapid gas pulses), while the NBF signal has a fundamental frequency of 7.5 Hz at idle, with the effective frequency range (due to the steepness of the pulse flanks) being a multiple of that.

With optimal circuit tuning using a 2-channel oscilloscope, a reliable, period-dependent delay of the NBF signal can be achieved.

This ensures that the original engine map is not distorted, but rather the overall injection start timing is raised to a higher level. Therefore, the dynamic injection start timing adjustment according to the engine map remains fully effective. At the same time, the usual advantages of powerbox tuning are maintained: cost-effective component sourcing, easy installation, and no modification of the EDC (Electronic Diesel Control) system.

Ideally, the circuit should have a transformer at its output, with a secondary winding that exhibits similar electrical characteristics to the NBF coil. Additionally, there's galvanic isolation to the EDC, which is always beneficial. The finished, encapsulated assembly is inserted into the NBF cable at any desired location and requires an ignition voltage and a ground connection.

Best regards,

Hello,

Of course, one could also adjust the desired values for the start of injection in the corresponding adaptation channel of the engine control unit by the desired amount.
Since the injection start curve for fuel consumption and performance is already suboptimal, a map-based adjustment would be the most sensible approach.

Best regards, Rainer.

Since the injection start curve for fuel consumption and performance is already suboptimal, a map-based adjustment would be the most sensible.

'I agree. However, the investments required for development work and hardware for engine mapping are significantly higher for private individuals.'

To my knowledge, there is programming software available for all engine types, but corresponding hardware interfaces (EEPROM programmers) are not readily available. Furthermore, pre-made, fuel-optimized maps are lacking for the countless engine types.

If one could obtain ready-made tuning maps and programming software for every engine and EDC type from companies like Kaaza & Co, and purchase a suitable EEPROM burner from Reichelt for just 5 euros, then power boxes would certainly become a thing of the past.

Unfortunately, engine tuning software that anyone can download doesn't exist, unlike with mobile phones, motherboards, and DivX players. The hardware and software requirements are kept secret by the tuning companies.

Am I mistaken?

Best regards,

EEPROM burners are available for purchase by anyone.

Schon klar. Aber haben die EDC auch gängige EEPROMS? (Ich habe meine EDC noch nie geöffnet). Können die EEPROM-Brenner auch das entsprechende Datenformat für die EDC brennen? FraPlease provide the text you would like me to translate from German to English.

Wäre super, wenn mal jemand ein Foto einer geöffneten EDC reinstellen könnte. InIt interests me.

Best regards,

Rainer K. wrote:

One could, of course, also adjust the target values for the start of injection in the corresponding adaptation channel of the engine control unit by the desired amount...

That's correct, and the result is independent of the speed.

By adding adaptation plus passive delay of the NBF signal, it is even possible to create various "slopes" of the curve of additional pre-emphasis and to shift the curve as a whole either earlier or later.

Considering these possibilities, I actually don't see a need for a "more complicated" electronic solution... no offense intended, Arosa SDI .

...especially since an adaptation is already becoming very apparent .

Cu Gremlin.

Considering these possibilities, I actually don't see a need for a 'more complicated' electronic solution... no offense, Arosa SDI .

When considering the costs associated with building a diagnostic adapter and the passive solution, the passive plus adapter method can even be more complex and expensive.

'But I have one more question: Why does EDC allow for a software-based adjustment of the injection start? Was there intentionally left room for optimization by enthusiasts, or are different 'slow' and 'fast' NBFs supposed to be adjusted?'

You're welcome. I'll be happy to explain.

@Rainer

I just discovered your diagnostic adapter kit. Well, the price is finally becoming more reasonable!

Nur die VAG-COM ist ein bißchen happig. Habe ich das richtig verstanden, daß man mit dem Bausatz eine 10€ billigere Version bekommt? Also 79€? Macht A total of €141.

Don't get me wrong, your profit margin might be perfectly legitimate, even generous. But for someone who doesn't have a network of friends or acquaintances who also drive TDIs and who only uses the part once a year, it's still too expensive. You can hardly make up for the cost through the fuel savings.

Therefore, my question is: Could one rent such a diagnostic adapter? Of course, with a deposit. This would be a cost-effective alternative for individual private users.

Best regards,

SeatArosa1.7SDI wrote:

@Rainer I just discovered your diagnostic adapter kit. Well, the price is finally becoming more reasonable! Nur die VAG-COM ist ein bißchen happig. Habe ich das richtig verstanden, daß man mit dem Bausatz eine 10€ billigere Version bekommt? Also 79€? Macht A total of €141. Don't get me wrong, your profit margin might be perfectly legitimate, even generous. But for someone who doesn't have a network of friends or acquaintances who also drive TDIs and who only uses the part once a year, it's still too expensive. You can hardly make up for the cost through the fuel savings. Therefore, my question is: Could such a diagnostic adapter also be rented? Of course, with a deposit. This would be a cost-effective alternative for individual private users. Regards

Hi, the kit includes the shareware version, which does not support saving values to the adaptation channels.
For that, you'll get a 10 Euro discount on the full version (which, of course, can modify the adaptation channels).

It really comes down to when you need the adapter. As long as you're not having any problems and just want to experiment a little, whether or not it's worth the investment is a matter of personal preference.
It definitely pays off if you take care of the maintenance of your vehicle yourself, or if you want to make certain modifications to the comfort features (e.g., installing automatic rain sensors).
The fact is that otherwise, when troubleshooting, you're pretty much stuck.

I've also considered renting it out, but the question is whether there would be enough demand.
If I were to rent out the professional systems, I would have to charge 20 euros per rental to make it worthwhile. In that case, the user would have to go to the bank and deposit a security, carry the PC to the garage, and later return the adapter... For that kind of hassle, it's almost worth just going to a workshop (for one-off jobs).

Also, seven months of rental would also cover the full VAG-COM software package.

Best regards, Rainer.

Yes, you're right. The absolute best approach would be if you had, for example, two other friends who also drive TDIs and are into tinkering, and you could pool your money together.

I'll do some investigating around here; maybe I can find someone. Of course, you have to trust each other, because if one person hoards something and doesn't share it, there will be trouble.

Carrying a PC would probably not be the problem, what's the point of a top laptop, uh, laptop?

Best regards,

Hi,

Just a heads-up: This thing works on any VAG car from around the early 90s onwards; it doesn't have to be a TDI or SDI model...

Best regards,

Jan.