Chiptuning: Check with VAGCOM?

Hello,

In connection with the update of the chip comparison, I wondered if it would be possible to analyze the work of chip tuners at least partially using VAGCOM.

Basic principle:
Before tuning, it's especially important to record data during certain test runs (e.g., full throttle from 1200 to 4500 rpm in 4th gear), particularly data related to fuel injection quantity and/or limits, boost pressure, and injection timing/fuel delivery start.

After the tuning, repeat the process and then compare the logs (if "before" logs don't exist, compare them to the logs of a standard, comparable vehicle).

At the very least, one could observe the behavior of the most important parameters at full throttle and see if, for example, the tuner is overstressing the turbocharger or, more likely, damaging the head gasket in an attempt to keep soot emissions within acceptable limits.
(Regarding boost pressure, even a simple turbocharger is sufficient.)

It is my opinion that one could potentially identify a "chip tuning" modification, similar to a 10c chip, by analyzing the voltage curve and injection quantity (in VP37 engines), where only the pump characteristic curve has been altered.

Analogously, a temperature sensor comparison could be used with the cooled PD engine: for example, if the diesel temperature is 40°C higher than the others, the tuner has made things very simple.

Before I incorporate this into the technical article, I wanted to ask the group if I'm on the right track.

Perhaps someone has some reliable practical experience regarding limits that should not be exceeded (e.g., not increasing the boost pressure in the upper RPM range above 0.2 bar ), which could also be included in the technical article...

Well, after the flood of responses, I tentatively included the ideas in the research article.

If anyone has different experiences, they can feel free to share them.

Here, our member ******** could share his experience and perhaps reveal a few secrets... *wink*

********.....JörgS: You're dreaming a little too loudly!

@Ulf: Who wants to hear from the community that their expensive chip might just be counterfeit? That's probably why there's so little interest. I'll see what I can find to give you some input.

********.....JörgS: You're dreaming a little too loudly!



Let me have a turn too...

Hello Ulf,

I think you should ask this question in the Chiptuningforum. The experts in this field are probably more likely to be found there than here.

I agree with all the points you listed, based on the fundamental idea.

However, there are many other parameters within the engine control unit besides those used in what is commonly referred to as 'chip tuning' (if such a thing can even be considered common), and those that you have mentioned.
Furthermore, the code also contains various conversion factors. For example, somewhere there must be a conversion from the boost sensor voltage to boost pressure (mbar). If a chip tuner were to simply adjust this factor and the offset, you would still see the original boost pressure in VAG-COM. With the appropriate in-depth knowledge and the Damos files, such tuning seems possible to me. However, I have never seen anything like this, nor have I heard of it, but I am also a beginner in this field.

Generally, I think that checking the pump pressure and boost pressure should provide sufficient information about the tuning in most cases.
Perhaps, in parallel, we could compare the fuel injection quantity limits. Do these limits roughly align, or was something simply arbitrarily increased that is now rendered ineffective by other limits?

Regards,
Private.

Hi Ulf,

You can view these things, for example, as cloud diagrams related to...
Speed. Aside from the time involved, I'm not sure if it's worth it.
besides the realization that it's 'different,' it retains something (ignoring the rough, unfinished aspects for now).
In addition, VAG-COM limits the maximum values because only 8-bit values are used. This affects the fuel injection quantity.
For example, a value is calculated using a factor of 0.2 -> 255 * 0.2 = 51mg. Therefore, you will never exceed a certain limit (at least for the VP values).
Received 51mg, regardless of the 16-bit value used in the control unit.


Best regards,

Rudi wrote:

In addition, VAG-COM limits the maximum values because only 8-bit values are used. This affects the fuel injection quantity. For example, a value is evaluated with a factor of 0.2 -> 255 * 0.2 = 51mg. Therefore, you will never receive more than 51mg (at least for the VP values), regardless of the 16-bit value used in the control unit.

Hi Rudi,

For me, the number of bits is currently more a question of resolution than of "scale".
Therefore, I suspect that the VP37 STGs may operate with a higher resolution internally, but the characteristic curves still end at 51 mg - or could the "8-bit output scale" actually be shorter than the internal calculation scale?

The logged limits for the ASZ (Air Spring Zone) reach up to 69.7 mg (driver request). The maximum injected amount, according to the torque limitation, is 55.7 mg.
The values are graded in alternating increments of 0.2 and 0.3 mg.

Hello Ulf,
The output scales are actually shorter. For example, my industrial AFN only...
up to an air mass of 850mg (which is equivalent to 255), although the characteristic curves extend up to 950.
(which also need to be achieved, otherwise the Russian restrictions would apply).

Best regards,

Rudi wrote:

The output scales are actually shorter. My industrial AFN, for example, only goes up to an air mass of 850mg (=255), even though the characteristic curves go up to 950.

Aha, I've learned something again .
(even though I don't quite understand the logic behind it - but oh well...)