Starke Zündwinkelrücknahme trotz 100Oktan-Sprit beim 2l TSI | Posts 16+

It would be interesting to see how much the ignition timing generally shifts towards being more advanced as load and engine speed increase (total timing advance). In older gasoline engines, the spark timing could be as advanced as 40 degrees before top dead center (BTDC).

With modern engines, everything is pushed to the limit anyway. Therefore, I wouldn't be particularly surprised if there was a slight reduction in ignition timing of just 5° at full load, considering that the engines are optimized for partial load operation.

I wouldn't worry about that just yet... maybe check it again after 10,000 km.

Quote:

By the way, even with e10 fuel and an outside temperature of 35°C, there is no reduction in ignition timing at maximum speed.

E10 requires a higher latent heat of vaporization and reduces the tendency for knocking due to improved internal cooling. Has anyone ever looked into the effect of retarding the ignition timing with a lower octane rating (95 or 91)? It would be interesting to see how quickly the limit is reached in those engines that always operate without ignition timing retardation with a 100+ octane rating.

Sure, here's the translation:

"Continued:"

Kindly, MED9.1 provides the MWB26 with all knocking sensor voltages – or, rather, what the MSG assigns to each cylinder based on the signals from the two sensors.
In the diagram, I have shown some Wide Open Throttle (WOT) acceleration phases (engine speed, indicated in green, increases) and the subsequent thrust phases that follow (indicated in green, decreases).
Yellow to purple represent the sensor voltages (peaks upwards), while the Z-axis retractions (peaks downwards) occur only during accelerations.

During the acceleration phases, nothing can trigger the knocking sensor, yet the sensor voltage increases with increasing engine speed. And they are quite different: Cylinders 3 and 4 are always close together, while cylinders 1 and 2 spread upwards and also scatter significantly among themselves.
Even though the software seems smart enough to at least attempt to adjust to the situation (instead of always giving cylinder 2 the strongest and longest injection pulse):
Is this the normal state of the art, or is it a warranty case?

By default, the MWB28 allows you to test the knock sensors. During this process, the engine automatically revs up to 2500 rpm, and then the display shows "System OK."
Logically, the large deviations in sensor voltages only occur at higher speeds.

Hi,

Quote:

or is it a warranty case?

...how can one convey this to a kind person? The vehicle is running and there are no visible problems during operation...

I don't think you can argue about that using VCDS...

Best regards,

Jan.

ulf wrote:

... During the compression strokes, nothing can knock. ...

Ulf has just developed a completely silent engine...

Unfortunately, your statement is simply not correct. The "knocking sensor" not only detects doorbell chimes, but all engine noises (and resonances) from which the doorbell chime signals are filtered out by software.
With that, you should now understand why cylinders 1 and 2 are showing significantly higher readings. Just so much... with a VW TDI, it wouldn't be like that .

Jan6K wrote:

...how can one convey this to the friendly person? The vehicle is running, and there are no visible problems during operation...

Yes (unfortunately)

Bertil wrote:

The "knocking sensor" not only detects doorbell chimes, but all engine noises (and resonances) from which the doorbell chime signals are filtered out by software. With that, you should now understand why cylinders 1 and 2 are showing significantly higher readings. Only this much... with a VW TDI, it wouldn't be like that

. What specific (front-end) noise source does the CDL have that a TDI doesn't?
Both have a timing belt drive. The chain in the CDL system only connects the two inner wheel ends, and it does so on the transmission side.
The LiMa (likely referring to a starter-generator or similar device) is located on the front of both engines.

Do you mean that equalization nonsense? AFAIK, it's more likely located on the forehead side rather than the coupling side.


Here's the diagram. The upload failed yesterday.

ulf wrote:

Do you mean that equalization nonsense?

That's where I see the "problem".
Okay... I forgot that the TDIs also come with that ridiculous energy-wasting module...


Okay, so your diagrams don't show anything unusual...

Bertil wrote:

ridiculous energy-wasting module

. I thought the same thing... and of course, about removing it.
The question is...
To what extent are the moving parts used to ensure that, for example, the oil pump is properly driven?
2. whether any of the smaller suspension components might be overloaded by the "natural" vibrations of the 4-cylinder engine and potentially fail prematurely?

Quote:

So, your diagrams don't show anything unusual...

Well, thank you for the reassurance.
So, we'll have to wait and see if the ZWR (zero-watt resonance) ever disappears – that would indicate that it's actually related to some kind of warm-up function.

New thought while I'm trying to get a handle on the MED9.1 software (wow, compared to this, an EDC15 seems like child's play).

The CDL engines are available from the factory with up to 280 horsepower (Scirocco R).
The WRC engine is nominally rated at 350 Nm and therefore has the same mapping for fuel injection, turbo boost, ignition timing, etc., but it is throttled from 4000 rpm onwards, such that its maximum power plateau of 220 hp is essentially achieved in the partial load range of the ignition timing map.

It's possible that when setting the ignition timing, the value used was significantly lower than the "correct" Pmax, or that there was a tendency to advance the timing to avoid increasing fuel consumption due to unnecessarily poor efficiency at a late ignition timing.