abgesenkte LL-Drehzahl und Öldruck | Posts 16+

faz wrote:

Could that also be it: Oil pressure switch 038 919 081 C? 0.55 - 0.85 bar, housing color brown

The color and printing match exactly , but I didn't read the part numbers.

That means, in plain language:
My oil pressure warning light will only reliably activate in the worst-case scenario when the engine speed reaches 1501 rpm and the oil pressure drops to 0.54 bar or less.

Therefore, if safe operation is still desired with just a slightly higher pressure, the automatic sharpening device (ASZ) must have virtually indestructible bearings.

ulf wrote:

.... Therefore, if operation is still to be safe with just a slightly higher pressure, the automatic screw feeder must have virtually indestructible bearings.

If you knew what your crankshaft drive and the bearings that support it look like, you wouldn't use the starter anymore.

I'm currently planning to install the Audi 80 auxiliary gauges in my A4.

And I am currently very shocked by your statements!

With the engine warmed up, only 1 bar of oil pressure is present at idle.

I only have the 2.8 engine as a reference from my wife's car. The idle pressure is 2.5 bar, and it's around 4.5 bar just above 1,500 RPM.

When I finally get the warning lights to come on in my car, I always think that my oil pressure is broken!

I always thought that the oil pressure in a TDI engine had to be higher due to the extreme stresses it endures.

Regards,

Manuel.

I always thought that the oil pressure in a TDI engine had to be higher due to the extreme loads.


no..

The required oil pressure depends solely on the overall design of the engine.
It is required that the oil be available in sufficient quantity and reliably at all lubrication points. The amount of pressure needed depends on the oil channels and primarily on the size of the bearings (throughput, clearance, width, design, etc.). The oil pump only needs to replace the oil expelled from the bearings or flush the bearing surfaces. Within the bearing itself, pressures up to well over 1000 bar can develop under load (combustion pressure).
Of course, 'auxiliary' components also play a role: turbochargers, fuel injectors for piston cooling, etc. To maintain high pressure in these systems, the oil pump's flow rate would have to be extremely high. At high engine speeds, all of this would then need to be bypassed.

I'm also wondering why VAG doesn't display the oil pressure until 1500 rpm.

CU Gremlin.

Okay, here's the translation:

"Something else:"

Since the LL (lambda) sensor was lowered, I've been hearing a distinct whistling sound at idle, which is interrupted in time with the ignition cycles. And it's not just coming from the exhaust pipes, but also from the direction of the engine compartment - although I haven't had time to investigate the source more closely yet.

After a brief burst of gas, everything is quiet. However, the whistling sound returns a few seconds after the low-speed (LL) engine speed is reached again.

According to that, it probably comes from the turbocharger (mine is extremely smooth, at least compared to the Garrett in the AFN - the Polo has a KKK), but frankly, that doesn't sound great to me, rather like something is wrong.

Does anyone have a better/more reliable explanation for this, or can someone provide information about potential defects?

@ulf:

If it makes you feel better, you can adjust the oil pressure warning threshold to a lower RPM using VAG-Com.

Quote (for 9N).

Ross Tech Support wrote:

-> Channel 35 (Adjustment of speed threshold). The adjustment value of 0 corresponds to a factory-set oil pressure warning that triggers when the oil pressure drops below 1.2 bar at an engine speed of 1500 rpm. The adjustment can be made in increments of 250 (0 - 1000). 0000 - 1000 RPM (Revolutions Per Minute) 0250 - 1750 RPM 0500 - 2000 RPM (Revolutions Per Minute) 0750 - 2250 RPM 1000 - 2500 RPM

Roger wrote:

@The adjustment value of 0 corresponds to a factory-set oil pressure warning, which triggers when the oil pressure drops below 1.2 bar at an engine speed of 1500 1/min. The adjustment can be made in increments of 250 (0 - 1000). 0000 - 1000 U/min 0250 - 1750 RPM 0500 - 2000 RPM (Revolutions Per Minute) 0750 - 2250 RPM 1000 - 2500 RPM Hmm, I had almost forgotten about that. But in my case, it's already coded as "0000", if I recall correctly. Only the 1000 threshold doesn't quite fit into the logic (see bolded entries).

And in my case, the pressure switch with a setting of 0.55 - 0.85 bar is installed (instead of 1.2 bar).

Hi,

To make it logical, the value 1500 should be in the table instead of 1000 – because then everything would fit together, and the adaptation value would simply be added to the 1500.

IMO, there's an error in the table.

Best regards,

January.

Jan6K wrote:

To make it logical, the number 1500 should be in the table instead of 1000 – then everything would fit, and the adaptation value would simply be added to the 1500. IMO, that is an error in the table.

I think so too. I remember once starting the car with the ignition switch not fully engaged (cold start).
After a few kilometers, I had to turn onto a main road, and it was only then that the pressure alarm went off when I revved the engine higher than usual (on that trip).

It's quite fitting that the alarm threshold should be set at 1500 rpm.
Even I would have started complaining within the range of 1000 to 1500 rpm, right after starting -> if 1000 rpm was set as an alarm threshold, it should have started beeping before even shifting from first gear into second.

You're right, I was momentarily distracted by the 1,000 frames per minute specification.

@Ulf:

Can you increase your idle speed above 940 RPM? Does the MSG store a value above the maximum value (which is 32838 = 945 RPM in my case), or does it only accept the maximum value?

The idle speed remains at 940 RPM, regardless of whether you enter 32838 or 32900. Does the MSG now also store 32900, or does it accept the maximum value of 32838 when the idle speed remains constant at 940 RPM? }

Julian wrote:

@Ulf: Can you increase your idle speed above 940 RPM? Does the MSG store a value above the maximum value (which is 32838 = 945 RPM in my case), or does it only accept the maximum value?

I once entered an extreme value, which then saved the adaptation maximum – around 940 rpm, if I recall correctly.

Quote:

The idle speed remains at 940 RPM, regardless of whether you enter 32838 or 32900.

Does the MSG now save 32900, or does it accept the maximum value of 32838 if the idle speed remains at 940 RPM?
I haven't tried it out extensively.

However, one should not forget the 21 rpm grid from VAGCOM:
That means that 945 rpm can remain at that value for as long as , provided the VAGCOM reading }, until the threshold for displaying 924 is reached.

My guess is that each single adaptation step changes the LL speed only minimally, but this change isn't noticeable until the next 21 threshold is crossed.


Regarding the oil pressure warning:
I just did another round with the connector unplugged. The alarm definitely doesn't come on until 1500 rpm.

-> My assumption is that each '1' adaptation step changes the LL speed minimally, but this change is only noticeable when the next '21' threshold is exceeded.

I can confirm that!

Belief and knowledge are two fundamentally different areas of study.

Even the Mercedes R107 had a nice pressure gauge in the speedometer. Even at idle when warm, it would read over 2.0 bar. Just tapping the accelerator and it quickly went above 3 bar. And that was already from the year 1978...

@Georg: I hope that as a Diplom-Ingenieur (Which field of study?), you have more to offer than just fortune-telling.

@Julian

I have clearly distinguished between what I believe and what I know.
I don't know anything about your engine, so my opinion is just based on what I believe!

Regarding Mercedes, I can confirm your observations; I miss their healthy oil pressures even more now.

My engineering degree has nothing to do with this topic! If you had looked at my profile, you would know that...
But of course, I have much more to offer!
Before studying, I completed an apprenticeship as a car mechanic, and much later, I was active in a motorsport club as a mechanic. And of course, I learned a lot about modified engines there. Well, most of them didn't have any electronics either, so they had nothing to do with modern, eco-friendly engines. But oil pressure and suitable motor oils were the main topics.

However, since some people here feel intimidated and put down by my title, I will remove 'Dipl.-Ing.' everywhere! (In this forum, it doesn't really mean anything; only knowledge and experience matter.)

So, in that sense, PEACE.

Okay, today I was 'messing around' with my colleague's Golf4 ALH in the MiPa (presumably a workshop or garage).

A pressure gauge was installed up to 10 bar instead of the oil pressure switch, and the cold engine (5°C) was started.

(5W-40 oil, engine with 51,000 km mileage, oil level at maximum).

-> Even during the startup process, the oil pressure rises to 4.5 bar and remains there, even at the factory-set speed of 903 RPM.

-> Reducing the speed to 840 RPM resulted in a pressure of 4.1 bar, while increasing the speed to 945 RPM yielded a pressure of 4.6 bar.

The engine was warmed up properly (revving a cold engine to 4000 RPM resulted in over 6 bar of pressure), and then it was driven normally back to the yard.

The coolant temperature was approximately 90°C, the oil pressure dropped to about 2.0 bar, and a change in the engine speed did not result in any measurable pressure differences.

The oil pump, at least for the ALH engine, is so powerful that you can safely reduce the low-speed idle speed.

I hope I have time to examine my AWX; only there is the conversion not as quickly completed as with the ALH.

Julian wrote:

The oil pump - at least for the ALH engine - is so powerful that you can safely reduce the idle speed (LL).

A reassuring result for the ALH members.

Unfortunately, the LL (low-level) setting on the Ibiza can only be reduced by approximately 20 rpm .