Full-load injection quantity setpoints: a cruel joke?

Hello,

As preparation for my future Polo, I'm gradually gathering information about PD (presumably referring to a specific model or feature).

But the specified diesel fuel amounts for full load seem *ahem* a bit strange to me.

For AXR, AZD, and ASZ engines, the smoke limitation (2800 - 3200 rpm) is 16 to 34 (36) mg per stroke.

As far as I understand the EDC rule strategy so far, the lowest limit always applies.
According to this, the 130 hp PD engine injects less fuel (16-34 mg) compared to, for example, the 110 hp VP engine (38-42 mg).

And the tolerance range is also quite peculiar: For the PDs, it's 1:2, while for the VPs it's only 1:1.1, which seems much more plausible to me.

But how, please, is a PD motor supposed to deliver acceptable performance with a full-load injection volume of 16 mg ?

Imagine the following:
The engine is running at roughly half of its normal power; I took it to the mechanic, who connected the diagnostic tool (part number 1551) and, after a test drive, said:
"The injection volume is still within the tolerance range, so everything is okay" (aside from the start of the injection, etc.).

Help, what does all of this mean??

Hello, the common rail diesel (PD) doesn't have a maximum injection pressure of 2050 bar for no reason.
This allows for better mixing of the diesel fuel with air and more complete combustion, which can lead to increased power (with sufficient air mass) or fuel savings.
That's precisely why it will consume less fuel (assuming you're not just constantly pressing the accelerator pedal).
With a heavy foot on the accelerator, fuel consumption is likely to be higher, which may explain the range of values.

I think you are overthinking things!

Because it's likely that the 34mg is included in the total amount when considering the full dosage.
Then the performance will improve as well.
And why is there a soot reduction requirement in the first place?
The boundary defines the characteristic curve depending on the load condition.
With a chip, the values are then set higher. For example, xx - 50mg or something like that.

I think you are overthinking it!

Because it's likely that the 34mg is included in the total amount when considering the full dosage.
Then the performance will improve as well.
And why is there a soot reduction requirement in the first place?
The boundary defines the characteristic curve depending on the load condition.
With a chip, the values are then set higher. For example, xx - 50mg or something like that.

hi,
The so-called 'map' refers to the torque limitation.
greetings

My ARL TDi has an emissions level of 53.8 mg/hour at 3000 RPM. The maximum value is approximately 2200 at 56 mg/H, and then it settles down to 53.8.

Based on my rough estimate, the 34mg/hub dosage seems reasonable for 100/105hp PD-TDIs...

Best regards, Rainer.

mersente wrote:

Hello, the PD (presumably referring to a specific device or system) doesn't have a maximum injection pressure of 2050 bar for no reason. This allows for better mixing of the diesel fuel with air and more complete combustion, which can lead to increased power (with sufficient air mass) or fuel savings. . . .

Hi,

I'd like to offer a different perspective, for example, by comparing the Golf 3 AFN engine with the Polo ASZ engine.

Both have a combined fuel consumption of 5.0 liters per 100 km, with the Polo (most likely) having a longer transmission ratio, which translates to better fuel efficiency, and also features electric power steering, which is said to save approximately 0.2 liters compared to the permanently driven steering system found in the Golf.

The difference in curb weight (according to the catalog, the Polo is 35 kg heavier) is likely negligible.