Lastmanagenemt: unnötig erhöhte LL-Drehzahl? | Posts 32+

Perhaps it's because you don't have glow plugs?
-> Battery should be charged quickly using the maximum charging rate. 'Should I increase the voltage to prevent the heating from being shut off again due to the power demand from charging?'


My ALH also only started running at higher speeds at arctic temperatures (below -5°C). I think, Ulf, that you are mistaken here, because the increase in engine speed is related to the exhaust behavior, not the turbocharger's boost pressure.

Julian wrote:

I think, Ulf, that you are mistaken here, because the increase in RPM is related to the exhaust behavior, not the charging behavior.

It's possible that I don't know the true "primary" reason for this programming.

The result, however, also benefits the (fast) battery charging process.

Hi,

However, the ALH and ASV engines have the same emission standard, namely Euro 3. Therefore, according to your theory, Julian, the ASV should also do that, but I don't recall that happening in previous seasons.

Let's see what he does this winter when it gets really freezing – I'll keep an eye on it.

Best regards,

Jan.

Jan6K wrote:

Let's see what he does this winter when it gets really freezing - I'll pay attention to it.

So, anyone who is somewhat familiar with their TDI "by ear" and is technically inclined will likely notice, even without looking at the tachometer, that it is behaving differently.

When searching for the explanation, you can see what's happening on the tachometer - and you should remember the deviation from the normally (without load) very stable idle speed of a VP-TDI engine. . .

Hi Ulf,

"Of course, you'll notice that... but I didn't experience much of it from last winter, because there were only a few days in Berlin that were really that cold, and my TDI probably experienced even fewer of those days, because it parks right next to a house wall at night..."

Best regards,

Jan.

@Ulf:

You could try verifying the "exhaust emissions" issue by temporarily reactivating the EGR system and resetting the mass airflow sensor for a few days.
My automotive service center has never encountered such idle speed increases before, even with the EGR system deactivated, but with the default air mass flow sensor setting.

It's possible that the diesel OBD device will trigger an error code again for you.

Roger wrote:

You could try verifying the "exhaust emissions" issue by temporarily reactivating the EGR system and resetting the mass airflow sensor value for a few days.

IMO not necessary... I'm slowly getting closer to understanding the load manager, and I can now reliably trigger or predict the LL (Load Limit) increase by observing the voltmeter and connecting appropriate loads .

Let's see if he'll ever surprise me with a behavior that doesn't fit the pattern.

Julian wrote:

So, I was tinkering with my acquaintance's Golf 4 (1J, ALH, 44,000 km, 5/00) yesterday... When the rear window/mirror heaters, all lights, seat heaters, etc. are turned on, the voltage drops briefly (~13.1V), but then rises again to 14.36V.

I've also started to notice it myself, although the charging system otherwise seems to be working perfectly normally.

In conventional control engineering, this would indicate an error, as voltage deviations in the range of 1/10 of a second need to be corrected.

However, with today's high-tech regulators (my regulator looks completely different from the "known" models), a sluggish power increase might be "not a bug, but a feature," to prevent sudden drops in engine speed and potentially other issues caused by a sudden surge in alternator power demand. To induce oscillations in the LL speed of the motor.
Because decreasing rotational speeds must be compensated for by an even greater driving force, since power equals torque multiplied by rotational speed.

Okay, in VP-TDIs with the very aggressive torque boost under load at low RPM, nothing would likely start to vibrate.
"In PDs, perhaps not, but with today's small, gasoline-powered engines, I fear that the load regulation may not be very 'self-stabilizing,' so that a slight increase in load by the alternator (even if it involves brief voltage dips, which are considered a lesser evil) is necessary to maintain the usual running characteristics." Avoid LL saws.

But with today's high-tech controllers (my controller looks completely different from the 'known' models), a sluggish power-up could be 'not a bug, but a feature'.

is it also...

It's called a load-response function, and it's designed to dampen hard impacts on the belt drive. Everyone knows this feature: 'the lights flicker at 2500 rpm' .

CU Gremlin.

Julian wrote:

@Ulf: Are you sure that everything is okay with the energy management system of your 9N? I don't consider 13V to be high for low-consumption devices; perhaps your limiter regulator has a fault.

Here's another update after a few measurements.

In the µCarge thread, I described how I measured the resistance of my B+ line using the 5A power supply.
Computationally, this resulted in a conductor resistance of approximately 1.6 mΩ (including a 175A fuse with 0.4 mΩ), which is roughly consistent with the expected value for a 1-meter length of 16mm² copper cable.

I just measured the voltage drop in the wiring after starting the engine, while the voltage is still rising towards 14V, meaning that the alternator, under full load, is primarily supplying power to the glow plugs and the battery's charging demand.

There were measurements of up to 110 mV, which, even at 840 motor rpm, suggests a current output of the alternator of around 70 A (nominal current = 90 A).

Gremlin's hypothesis is that the resistance of the fuse increases under load (due to potential contact problems or...). The expected increase (due to warming) has not been confirmed: 25 mV above the threshold value corresponds quite accurately to their proportion of approximately 25% of the total cold resistance.

Even a rough calculation of the acceptable load until the battery voltage drops when the engine is warm (LL = 840 rpm) doesn't reveal anything fundamentally different:

-> Rear window defroster = 17 A (just measured).
-> Heater fan at full power = 16A.
-> Headlight (low beam), headlight (high beam), and parking light combined, approximately 19A.
-> Pre-filter pump = 4 A
-> Power steering with pump in the left-hand side = approximately 2 A.
They have been together for 58 years.

In addition, there's the difficult-to-estimate power consumption of the engine (PDE, magnetic valves, TCU), as well as small consumers like the instrument cluster, ABS, and likely some current draw for charging the battery, which probably never fully charges on my mostly short trips.

The result is trending towards 70A again, which already brings my small 90A LiMa to a reduced idle speed -> Respect .

If I have the brake (6 A) and NSL (2 A) engaged, and also, illegally, the NSW (8 A), the battery would definitely be discharged in the LL (low-load mode), so the load manager would urgently need to increase the speed – even without afterglow or active electric heating.

It's good and also entertaining to have a voltmeter on board so I can monitor the whole thing additionally.