Load management: unnecessarily high LL speed?

Hello,

My Polo already benefits from the advantages of the CAN bus era and electronic load management. The latter refers to monitoring the onboard voltage, along with implementing measures to prevent battery discharge.

According to the SSP (Service Information), if the on-board voltage drops below 12.7 volts, the idle speed should be increased. Furthermore, if the voltage drops below 12.2 volts, various power-consuming components should be switched off sequentially (rear window heater, seat heaters, mirror heaters, air conditioning).
As the voltage increases, the loads are reconnected, and finally, the LL speed is reduced to its normal value.

This morning, for the second time, I noticed an increased LL (likely referring to a specific system or component) speed (~1000 rpm), which is particularly noticeable compared to the adapted normal value of 840 rpm.
While I could achieve almost the same level of initial acceleration without gas as I could with a VP-TDI engine, a glance at my analog on-board voltage display showed a full voltage of almost 15 volts (which is normal after a cold start).
After approximately 45 seconds, the LL speed was adjusted back to the normal level.

I first noticed the increased LL (likely referring to a specific engine component or system) speed about a week ago, immediately after I reactivated the glow plug system (I usually disconnect the fuse during the summer).
"At that point, I just thought that must be the reason, because the lower LL (low load) speed might not have been sufficient to maintain the 12.7 volts, even after the initial charging and afterglow."

"However, since then, I've experienced several cold starts at similar or even lower temperatures, without any increase in the LL (low-level) engine speed." This morning, it was even warmer again, and yet the engine still stalled.

The battery was not more discharged than usual (or discharged since the last time it was turned off using the radio or something similar).

Can anyone come up with a rhyme for that? Could my car's onboard computer be experiencing occasional glitches?

Can anyone come up with a rhyme for that? Does my vehicle's onboard network control unit possibly have a sporadic malfunction?

Take a look at the lighting equipment utilization. If it's hovering around 100%, that's normal behavior.

CU Gremlin.

Gremlin wrote:

Take a look at the lighting equipment utilization while doing that. If it's hovering around 100%, then the behavior is fine.

Hm, then I would probably run the Lappi x times for free, because the situation is (still) not predictable or provokable for me.

If it depends on the utilization rate, that would imply that load management...
a) receives information about the breast pump's usage (presumably via CAN).
and
b) the LL speed is also increased "preventatively," even though the onboard voltage has not yet decreased, and the SSP is therefore incomplete (-> see above "below 12.7 volts" )

Can you confirm that?

Does my AWX still work, but only up to about 1000 RPM and at outdoor temperatures below 5°C?

At the time, the utilization of my Lima regulator was around 40%, and the voltage was approximately 14.14V. Therefore, I believe it's simply a matter of an idle speed adjustment related to the catalytic converter warm-up and the Euro3 standard.
Once you get it started and the engine is running, the sputtering usually stops after a few seconds. If it were a collapsing board voltage, those few seconds of increased voltage wouldn't help much.

However, there's also a significant difference here compared to the ALH (D3) that I used to drive. When it was really cold (-15°C, even the engine was cold), it would idle up to 1300 RPM. The AWX engine never really exceeded 1000 RPM.

I observed the same thing with my AWX last winter. The maximum speed was around 1000 RPM at -15 degrees Celsius, and that was only for a short period.

Julian wrote:

If it were a collapsing board voltage, those few seconds of increase wouldn't help much.

It's possible that the system checks whether the normal speed is sufficient again.
For example, the battery draws a significant charging current immediately after starting, which decreases noticeably within just a few seconds.

Quote:

However, there's also a significant difference here compared to the ALH (D3) that I drove before. When it was really cold (-15°C, even the engine was cold), it would idle up to 1300 RPM; the AWX engine never really exceeded 1000 RPM.

For our cars (ASZ / ALH), it's essentially the same thing.
I haven't been able to identify a clear pattern for when the upper limit (LL) is raised in my case... well, I'll keep observing.

Hi,

Quote:

Immediately after I reactivated the glow plug system (I usually remove the fuse during the summer).

Not directly related to the topic... but... Why are you doing that? You're mainly preventing the "Nachglühen" (afterglow), which also happens in the summer. Are you trying to extend the life of the candles, or is your primary concern about fuel consumption in the first few minutes?

Best regards,

Jan, whose car has now passed the TÜV and ASU inspections and is valid for the next two years.

Hi,

The load of the alternator (Lima) is also monitored in the "older" TDis models without CAN, using the alternator's DF connection. The duty cycle on the DF signal indicates the load (a higher "ON" time corresponds to a higher load). My AFN (Auxiliary Fuel Network) has also (in rare cases) experienced a LL (low level) alarm, but more likely, large consumers controlled by the MSTG (Main Steam Turbine Generator), such as preheating systems for cooling water, would be shut down.

Greetings.
dieter

Not directly related to the topic... but... Why are you doing that? You're mainly preventing the 'Nachglühen' (afterglow), which also happens in the summer. Are you trying to extend the life of the candles, or is your primary concern about fuel consumption in the first few minutes?



to save weight??!!!!! *quickly move away*

joergs wrote:

Jan6K wrote: That's mainly to prevent the after-gluing, which is also done in the summer. Are you trying to extend the life of the candles, or is your primary concern about fuel consumption in the first few minutes? to save weight??!!!!! *quickly move away*

I hadn't even thought of that . The fuse is also "unlosable" on board, even in the summer.

@Jan: Both answers are correct .

A friend with a Leon (81 kW) already experienced rough cold starts after just 2 1/2 years -> likely the first spark plug is broken.
When I look at the excessively long afterglow times of our Ibi (even after warm starts ), and I extrapolate that to the Leon, I'm not really surprised...
Oh yes: The Ibi candles, of course, also always have a summer break .

Of course, the Ibi candles also always have a summer break .

And the results?

Think about the PDEs; they also draw enough power, and an ASZ (air conditioning system) will certainly also run with only 2 or 3 functional PDEs.

Which brand of spark plugs does your car originally come with?

Julian wrote:

ulf wrote: Of course, the Ibi candles also take a summer break And what about the results?

3 1/2 years, almost 40,000 km, no broken spark plugs yet, and according to the onboard computer, there's a difference of about 0.1 - 0.2 liters in fuel consumption (this difference is quite noticeable immediately after the engine is turned off or started, even without a sudden change in the average outside temperature) .
And there are no noticeable drawbacks (just like with the G3).

Quote:

Think about the PDEs; they also draw enough power, and an ASZ (Air Suspension System) will certainly still function with only 2 or 3 working PDEs.

But if I turn it off, I always get those annoying error messages...

Quote:

Which brand of spark plugs does your car have installed from the factory?

*pondering* all three are Beru, if I recall correctly.

Okay, I took a closer look again this morning:

Immediately after starting, my 90A alternator, even at the reduced low-speed setting, is unable to raise the onboard voltage to 14 volts to power the consumers (afterglow, battery charging, engine, and headlights) – it only manages to creep up from 12.5 towards 13.
In this scenario, the utilization of the liquid milk production line will inevitably be 100%.

So, after a few seconds, it appears that the load manager kicks in and increases performance based on the LL (low-level) speed – that's at least what it looked like to me this morning.

The question is, why doesn't this happen every cold morning since my glow plug system was "repaired"...

In this scenario, the utilization of the liquid milk production line will inevitably be 100%.


Were you unable to read the percentages in any of the MWB documents within the MSG?

Julian wrote:

ulf wrote: In this case, the LiMa utilization will inevitably be 100%. Were you unable to read the percentages in any of the MWB (Multi-Wave Beam) devices in the MSG (Meteorological Satellite Ground Station)?

No. The value can be accessed via the MSG, but I only carry the laptop with me in exceptional cases.

Since the Lima hasn't been causing any problems so far, I assume it's functioning normally.
This means that the regulator provides full power (100%) when the output voltage is below the target voltage (approximately 14.5 V, depending on the temperature).

Hmm, that's strange. My battery voltage has never been much above 14.2V, and during a proper cold start, the generator load has never exceeded 45%, which would be approximately 63A.
And I have more consumers 'in the system' than you do... fascinating!

What is the capacity of your battery?