TDI Intake Manifold: 16V Models

Hi.

Does anyone know the logic used to control the intake manifold on the PD-16V engine?
(On a PD controller, it's only adjustable in steps, while a CR controller can adjust it continuously.)

I have a log file, but I can't understand the logic behind it.

Hi Martin,

The logic is already difficult to understand. However, the likely principle is that a map based on load and engine speed switches between swirl (valves closed) or charge (valves open). This could be done continuously or digitally, possibly with additional hysteresis.

To get a more accurate result, more consistent conditions need to be added to the log.

- Full-load acceleration
- Gently accelerate from idle using approximately two-thirds pedal travel, and then maintain that speed as smoothly as possible. - Ideally, do this in various gears.
- Use the cruise control while going up and down hills, but ensure there is no acceleration occurring.

Make sure to pay attention to all actions and ensure that the device is switching properly. If it's not, adjust the speed or load range.



Based on what can be seen in the log, at idle, it exhibits swirl; this tendency also appears with large injection amounts despite a higher RPM. Under light load and low RPM, it shows a tendency towards stratification. However, under thrust conditions, it reverts to swirl again.
Under full load, it's likely that the engine would start to experience a lack of air at some point during its RPM range.
(Small TV = Drizzle, Large TV = Filling)

The challenging aspect is that the swirl flaps primarily serve an exhaust-related function. Because the New European Driving Cycle (NEDC) allows for compensating multiple emissions from one operating condition with those from another, it's possible to achieve some very unusual results regarding hysteresis and other factors.
I also think some kind of fuzzy logic would be conceivable.

But the logic will likely be that a map based on load and RPM switches between swirl (valves closed) or charge (valves open). Either continuously or digitally, with possibly an additional hysteresis.
(..) Since the NEFZ (New European Driving Cycle) allows for multiple missions within a specific area to be compensated across different operating states (areas), it's possible to achieve some very unusual results regarding hysteresis and other phenomena.
I would also find some kind of fuzzy logic conceivable.

Hello Malte,

You have a lot of nice ideas about what all could happen .
However, this speculation doesn't really lead to an answer to Martin's question.

The function of the swirl flaps can be described as follows:

The swirl flaps can only be in the 'open' or 'closed' position. Without vacuum pressure at the vacuum sensor, the swirl flaps are in the 'open' position (emergency mode).

By increasing the flow velocity when the swirl valve is closed and by designing and arranging the swirl channel, the intake swirl in the cylinder increases at low air intake rates. This desired effect enhances the rotational movement of the incoming gas. This rotation and higher flow velocity are particularly important in the lower engine speed range and at low torque levels to ensure better fuel-air mixing. This results in reduced fuel consumption and lower emissions.

The swirl flaps are kept closed within the engine speed range of 950 rpm to 2200 rpm, depending on the engine torque . During engine start and in idle mode, the swirl flaps are always open.

At higher speeds and torque levels, the swirl flap opens to achieve a better cylinder filling.

The control of the throttle valve (N316) for the intake manifold is performed by the engine control module (ECM) via a characteristic map.

In a CR system, this control is continuous and depends on the load and motor speed. This ensures that an optimal airflow is available for each operating condition.

One more reason why the CR is Euro5 compliant...

Best regards, Jochen.

Jochen_145 wrote:

One more reason why the CR is Euro5 compliant...

Hi there,

Do you also have emission data for this? Because other manufacturers have been using piezo injectors in common rail (CR) systems for 4 years or more, sometimes combined with a variable intake manifold and swirl flaps (also known as Venturi effect to prevent scavenging from extreme valve timings). I'd be interested to know the difference in emission values compared to engines that use the successor injectors from SID303/301.

Quote:

The swirl flaps are kept closed within the engine speed range of 950 rpm to 2200 rpm, depending on the engine torque. At engine start and in idle mode, the swirl flaps are always open. At higher speeds and torque levels, the swirl flap opens to achieve a better cylinder filling.

That's approximately what I was looking for.

I had previously thought that the flaps were only speed-dependent. And when I tested my new 12V Metz device for the laptop, I quickly looked for the swirl flaps as well...


Thank you.
Sure, here is the translation of the text from German to English:

"m" translates to "male" in English.