Loader Safety Pause After Engine Start

Hello,

I'm considering adding a relay or switching transistor to the control circuit of the turbocharger wastegate solenoid valve, which would delay the completion of the circuit for approximately 5 seconds after the engine starts.

Purpose: To prevent the loader from over-revving before it has oil pressure.

It probably makes more sense for me than for many others, because I often turn off the engine when I'm stopped, especially at traffic lights, and sometimes I have to drive off immediately after starting it to avoid blocking traffic.
Then I always think, "Hopefully, the loader already has oil pressure."

With this setup, I could essentially floor it without any issues, because without power, the VTG (variable turbine geometry) is at its minimum pressure build-up, and it takes about 5 seconds to build up boost.

I would tap the "Engine running" signal at the alternator excitation terminal.

Are there any foreseeable problems with this project that might be caused by the engine management system?

Given the error message "Solenoid valve interruption," I would connect a resistor in the kOhm range in parallel with the timer.
With a valve-winding resistor of approximately 16 ohms and the corresponding power requirements, the valve would likely remain completely sealed with a 1 kOhm resistor in series, while the EDC would think that the circuit is okay (I've tried it: fake values up to 10 kOhm were accepted - then I stopped...).

MotorMGMT:

Okay, but what happens if you're really pushing it hard right now, and the VTG (Variable Turbine Geometry) is still in its winter mode, and the MSTG (Motor Steuergerät - Engine Control Unit) starts to panic because it's not getting any boost pressure, and it goes into emergency mode (after a 575 error code is triggered)?

You might be able to experimentally determine the maximum time for the winter sleep mode here, but there's a "risk" that the EDC will detect it and "overreact."

And if you end up in emergency mode afterward, you're guaranteed to become an obstruction in traffic.

m;

Do you have a vacation, or why are you currently taking the "Preparations Course Polo" ?

Hi Ulf,

I assume that when a motor is turned off, the oil doesn't drain back down so quickly that it takes a while for the oil pressure to build up again after restarting.

How about checking the effectiveness of your measure first by using an oil pressure gauge?
It's not as if the turbocharger doesn't have any lubrication. And by the time the engine reaches a speed where the turbocharger needs good lubrication, the oil pressure is certainly more than sufficient.

Best regards,
Eike.

If you're really concerned about it,
Then tackle the problem at its root and install an oil pressure accumulator with a solenoid valve.
The pressure accumulator is connected to the oil circuit and is 'pressurized' by the oil pressure.
When the engine is turned off, the solenoid valve closes immediately.
The pressure is maintained and is immediately available upon startup.

It is also often used in racing cars to maintain constant oil pressure during turns.
It's called a pre-oiler, or something like that.

dieselmartin wrote:

Yes, but what do you do if you really push it hard now, and the VTG is still in winter mode, and the MSTG gets panicked because there's no boost pressure, and it goes into emergency mode (after a 575 error is cleared)? You might be able to experimentally determine the maximum time for hibernation here - but the "risk" that the EDC notices it and "over"reacts remains.

Yes, I will take that test.
For extreme cases, it might be possible to "pre-engage" the gear shift by using the full-throttle pedal contact.

Quote:

Are you on vacation, or why are you currently taking the "Preparations Course Polo"

I am taking the time for it .

leolotus wrote:

Then, tackle the problem at its root and install an oil pressure accumulator with a solenoid valve. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. It is also often used in racing cars to maintain constant oil pressure during turns. It's called a pre-oiler or something like that.

That would be too much effort considering a small circuit board with a material value of approximately 3 euros.

Then I always think, 'Hopefully, the loader already has oil pressure.'

With this setup, I could essentially floor it without any issues, because without power, the VTG (variable turbine geometry) is at its minimum pressure build-up, and it takes about 5 seconds to build up boost.


The circuit probably works, but I don't really understand the purpose. The bearings are usually oil-hardened (whether they are rolling bearings or plain bearings), and they can run for quite a while without any oil supply.
If you start the engine when it's cold (a pre-heater is great), the oil is quite viscous, which creates good oil pressure. If you stop a warm engine at a traffic light, there's already enough oil distributed in the bearings (bushings) so that starting is completely irrelevant for the lifespan. The lubricated bearing receives new oil within milliseconds, and that's perfectly sufficient.
In our material testing at the university and at SKF, we have intentionally destroyed bearings as demonstration pieces, for example, causing oil-hardened bearings to corrode without oil, which took a very long time. Ball bearings are somewhat more susceptible to damage in this regard than plain bearings, which tend to experience more wear than immediate destruction.

Contaminants entering the oil significantly shorten the lifespan, as these particles are extremely abrasive to the bearing surfaces. Therefore, a fine filter is clearly the preferred option (although extending maintenance intervals should be avoided!).

Maintain the oil level at the maximum mark; this is the optimal level for the machine.

Julian wrote:

The circuit probably works, but I don't really understand the purpose. The bearings are usually oil-hardened (whether they are RiKula or plain bearings), and they can run for quite a while without any oil supply. If you start the engine when it's cold (a heated engine is great), the oil is quite viscous, which creates good oil pressure. If you stop a warm engine at a traffic light, there's already enough oil distributed in the bearings (bushings) so that the start-up process is completely irrelevant for the lifespan. The lubricated bearing receives new oil within milliseconds, and that's perfectly sufficient.

It might be true... on the other hand, I still remember a warning sign in my R5 Alpine Turbo (manufactured around 1980) that, in essence, said:
"To avoid damaging the starter, do not rev the engine to high speeds in the first 20(?) seconds after starting it."

What other reason could there be / have been besides a "no-load" operation of the charger?
Especially after a cold start, high oil pressure builds up immediately – but only because the oil is viscous and therefore takes significantly longer to flow, for example, through the long, thin pressure pipe to the turbocharger.

On the other hand, my aunt's 525TD has been running perfectly for 10 years in a 'housewife' environment, and it's started and warmed up regularly.

I'm not entirely sure I understand the logic behind your approach...

CU Gremlin.

Gremlin wrote:

On the other hand, my aunt's 525TD has been running in a "housewife" operation for 10 years without any problems, and it is started and warmed up... I can therefore also not fully understand the meaning of your design...

Okay, so let me rephrase that:

1. Optimal safety / wear protection for the loader.

Here's the translation:

"Again, a small DIY project that also intrigues me somewhat."

If one BMW apparently doesn't need such a circuit, then I don't think that necessarily applies to my car, or to VW in general.

Unfortunately, it is unknown how many faulty TDI turbochargers would still be functioning if such a system had been installed (or if the EDC had been programmed accordingly).

It might be true... on the other hand, I still remember a warning sign in my R5 Alpine Turbo (manufactured around 1980).
What other reason could there be / have been besides a 'dry run' of the charger?


Reason: The tolerances. The components of today's production engines meet such a high standard that it wasn't even required in F1 engines back then. Emission regulations and the efficiency of the combustion process now largely determine the design of the components. By the way... has Renault ever built good engines?

And I find it highly unlikely that you would accelerate from a traffic light with full throttle and the corresponding high engine speeds.


Especially after a cold start, high oil pressure builds up immediately - but only because the oil is viscous and therefore takes significantly longer to, for example, be pushed through the long, thin pressure pipe to the turbocharger.

Well, 0W-30 oil isn't necessarily very viscous. You could try putting a sample in the refrigerator or freezer; it only became noticeably thicker at temperatures below -30°C in the freezer.

Your turbocharger won't run out of oil while the engine is idling. When the oil pump draws oil in during startup, oil is immediately forced into the turbocharger bearings, long before the engine can even run independently without starter assistance.

Julian wrote:

ulf wrote: It might be true... on the other hand, I still remember a warning sign in my R5 Alpine Turbo (manufactured around 1980). What other reason could it have / could it have had besides a "dry run" of the charger? Reason: The tolerances. The components of today's production engines meet such a high standard that it wasn't even required in F1 engines back then. Emission regulations and the efficiency of the combustion process now largely determine the design of the components. .

Hi Julian,

It's nice to know... but I'm still not clear on how the tolerances of the engines relate to the issue of dry running of the turbocharger.

And it's likely that the pump was already delivering oil before the engine started, due to the "organ-like" sound of the starter motor, just as it was in the 1980s, and still is today...

It's nice to know... but I'm still not clear on how the tolerances of the engines relate to the issue of dry running of the turbocharger.


Okay, this refers to all the attachments. This also applies to the bearings of the loader shaft. Just think about the loader performance today versus in the past.
I'm not familiar with the specifics of your R5 Alpina, but regarding the ALH engine, I can only say that the oil wasn't returning from the turbocharger back to the oil pan. The lines were always full. It's likely the same situation with the AWX engine (not yet verified).


And it's likely that the pump was already delivering oil before the engine started, due to the 'organ-like' sound of the starter motor, just as it was in the 1980s, and still is today...


Okay, so our SLC 450 (1978) still had a nice pressure gauge for the oil pressure in the dashboard. The oil pressure wouldn't register until after a short burst of acceleration, reaching about 2-3 bar. My AWX already exceeds that mark right after starting.
Over the years of production, the engine oil volume has also generally decreased. The oil flow paths are continuously optimized to reduce the power loss of the oil pump and to ensure a defined 'oil collection point' (where sludge formation is limited to a specific, accessible area). The system is also designed to ensure that critical components are immediately supplied with oil.
That used to be less important with standard engines; the main thing was not to get too hot and to have enough oil. Oil consumption was also a secondary concern in the past, but today...?

edit/
'Hey Ulf, here's something I was thinking about regarding your R5: When starting the engine, a relatively large amount of fuel is injected (a rich mixture). If you then suddenly rev the engine up to its maximum, it's possible that the turbocharger could temporarily overheat. Older turbocharger models weren't as temperature-stable as the ones we have today. Nowadays (e.g., 1.8T engines with 190/210/225 horsepower), there's even a dedicated temperature sensor on the turbocharger to prevent it from being supplied with exhaust gases that are too hot, which could cause it to fail prematurely. Perhaps that's the reason for the note you mentioned about your R5. *pondering*'

ulf wrote:

And that the pump is already delivering oil due to the "orgling" starter motor, even before the engine starts, was probably just as true in the 1980s as it is today.

Hi,
"Tight tolerances in the oil pump mean fewer oil leaks, which results in higher pressure even at very low engine speeds. In addition, there are improvements in the design."

Julian wrote:

@Ulf: What I can also imagine regarding your R5: When starting, a relatively large amount of fuel is injected (a rich mixture), and if you suddenly rev the engine very high, it's possible that the turbocharger could temporarily overheat. . . . *enthusiastically speculating*

*ggg* My R5 with 108 horsepower still had a carburetor before the turbocharger (and, incidentally, it didn't have an intercooler, but an oil-air cooler).
Do not confuse this with the "Hamsterbacken" rally car, which features K-Jetronic and 160 horsepower in its road-legal version.

But injecting grease into my Renault definitely wouldn't fix anything (except perhaps through the fuel accelerator pump).

The Renault dealer's explanation, as I recall, also involved lubrication.
What, however, doesn't necessarily have to be true - considering what workshops sometimes say...

Hello Ulf,

When a car sits for a long time, the oil drains back and the lines become empty. Then, especially with a cold engine and long oil lines with large dead volumes (like your Alpine oil cooler with its pipes), it takes a long time for the oil to reach all parts and for pressure to build up in the bearings. At a traffic light, there isn't enough time for that to happen. Furthermore, all the bearing locations still have enough oil to last for a few minutes without further oil supply. If you disconnect the oil pump before the first start in the morning, it will seize up much faster. Therefore, switching the car on and off won't make much difference. An electric oil pump is more advantageous, as it builds up pressure before the first cold start and fills the empty spaces.

Best regards,
Christian.

A large note was included with my new turbocharger, advising that before starting the engine, it should be cranked for at least 20 seconds using the starter motor only, to fill the oil lines with oil, otherwise, serious damage to the turbocharger is likely to occur.

Since it's not possible to do that while the vehicle is in operation, there must be a mechanism to prevent the lines from running empty, even when the vehicle is parked at an angle (e.g., a check valve?).

I also think your idea of "turbo protection" is unnecessary. After all, there are drivers who start their TDI with the accelerator pedal fully pressed and immediately take off. Even for these drivers, the turbocharger needs to last a reasonable amount of time.

If the loader is handled carefully, the inadequate oil supply should not be the cause of any damage or wear.

Best regards,
Uwe