Low Boost Pressure: Long-Term Troubleshooting

Hello everyone!

Having already started a different thread and being very impressed with the quick and, above all, helpful responses, I'm trying my luck again:

"I've been dealing with this problem for over 3 years. The error message I'm encountering is:"
"000665 - Charge pressure control, P0299 - 000 - Control limit exceeded - Intermittent". Complete vehicle scan attached!

I admit it – it's not necessarily a rare mistake. There's plenty of reading material available on the subject. However, I've already tried everything I've read. Now, for the details:

It always happens within the range of 2,000 – 2,400 RPM when accelerating moderately. This usually occurs on the highway at a speed of 100 km/h in 6th gear, while accelerating from 100 km/h to 130 km/h after exiting a tunnel, and going slightly uphill. The preheating light comes on along with the "limp home" mode. Turning off the ignition and turning it back on resolves the issue, allowing you to press the accelerator further and continue driving... The problem doesn't seem to occur in lower gears (1st-3rd gear) or when accelerating fully within this RPM range, suggesting that there is sufficient boost pressure at those times?

What has already been done?
1. Hoses and other components were visually inspected for damage.
2. Nothing found, so the turbocharger pressure sensor was replaced.
3. Nothing worked, so a diode trick was applied to the mass airflow sensor (to avoid an unnecessary purchase), but the error still persists.
4. VTG vanes inspected and functioning perfectly. The owner is desperate because even the turbocharger exhaust housing was disassembled and the guide ring (and entire mechanism) were checked - it's working flawlessly!
5. The throttle body, EGR valve, and intake manifold were cleaned of carbon deposits (which were significant, having accumulated over approximately 300,000 km), and then reassembled.
"In the process, I reused the old seals, which turned out to be a mistake after 1 year. Since I saw oil traces below the turbocharger, I knew that the boost pressure was leaking. Using the "test" function in VCDS, under basic settings -> boost control, I could confirm this. The engine revs up to 1400 rpm and activates/deactivates the VTG (variable turbine geometry). While the VTG is activated, you can clearly hear the escaping air (which gave me another opportunity to verify that the VTG and vacuum pump are working correctly). So, I disassembled everything again a few days ago (the intake path was surprisingly clean), reassembled it with new seals – no noise anymore, it's tight! However, the error code is still present!"
7. In the meantime, I also checked the vacuum system for leaks, as it's possible that within this specific RPM range, when the swirl flaps (controlled by a vacuum actuator!) are activated, the vacuum pressure may not be sufficient for the VTG (Variable Turbine Geometry). However, despite how promising that sounded: everything is working perfectly and is leak-free (checked with a vacuum pump). So, that wasn't the problem either.
8. And to go even further back in time: There was also the suspicion that the turbocharger wasn't providing enough boost (perhaps due to excessive back pressure from the DPF or insufficient exhaust gases due to worn piston rings?!). Therefore, a blank DPF simulator (FOR TESTING PURPOSES ONLY!) along with corresponding "tuning" software for 140 horsepower, which disabled the DPF, was installed. This resulted in slightly more power, and the error also occurred somewhat less frequently, but still regularly!

I'm not sure if I've listed everything - maybe I remember something else. As one might assume, I'm a bit annoyed. I'm also increasingly noticing that the performance when starting in first gear (especially now in the summer due to the warm air) is decreasing (but it could also be due to my nerves ).

Finally, a side note: The turbocharger is original only on the exhaust side. Since I actually wanted to chip it, it received a larger compressor (from a GT1752V) along with a new block assembly (from Holex, Germany). However, tuning is not an option at the moment, as the symptom becomes more pronounced with increasing power (I had test software for tuning installed).

I'm already looking forward to seeing what information you provide, or whether there might even be a fellow enthusiast .

Hi,

Quote:

Finally, a side note: The turbo is only original on the exhaust side.

That could already be the cause. Furthermore, the variable turbine geometry (VTG) is located on the intake side, not the exhaust side. The engine control unit controls the VTG according to the load conditions, and then regulates the boost pressure.
Due to the modified turbocharger, the calibration map for the variable turbine geometry (VTG) control in the engine control unit no longer matches the turbocharger.

To rule out leaks in the charge air system (pipes/intercooler), it would be helpful to perform a full-throttle test in 3rd gear at 1200-4000 rpm, while monitoring the target boost pressure, actual boost pressure, engine speed, and measured airflow (ensuring the mass airflow sensor is functioning correctly).

Also, please also check all the vacuum connections (vacuum reservoirs, solenoid valves) again to see if any of the plastic connectors have cracked. It's rare, but it has happened to me before.

Best regards, Rainer.

I'm going to post this log here. However, I doubt that the charger is the cause, because if it were, the tuning file should have worked. But instead, things only got worse – or am I drawing the wrong conclusion?

alm0st.un1que wrote:

I'll post this log here. However, I doubt that the charger is the cause, because if it were, the tuning file should have worked. But instead, things got even worse – or am I drawing the wrong conclusion?

First of all, your original file should work; you should create a log as I suggested, and the turbocharger modification, if I may say so, is quite cumbersome because there's a suitable KKK original turbocharger (BV43) that easily provides enough power for 210 horsepower.
I would say that tuning the engine with a mileage of 330,000 kilometers is, to put it mildly, not ideal.

Another point to note is that the connection of the exhaust temperature sensor on the turbocharger can come loose, which can result in insufficient boost pressure because the escaping exhaust gases reduce the amount of drive energy received by the turbocharger.

Best regards, Rainer.

dieselschrauber wrote:

The connection of the exhaust temperature sensor on the turbocharger may come loose, which can result in insufficient boost pressure because the escaping exhaust gas reduces the amount of drive energy received by the turbocharger. Best regards, Rainer

My list wasn't complete after all... Unfortunately, I've already checked everything – all the screws, including those on the DPF.
I had a hairline crack in the exhaust manifold, which was also replaced along with a new gasket. Definitely everything is sealed up to the exhaust gas recirculation system.

Thank you for the tip about the KKK charger!

dieselschrauber wrote:

...because there is a suitable KKK original charger (BV43) that easily provides enough power for 210 horsepower.

Let's revisit this: Is that the turbocharger from the CR engine? Can you even install it like that, without any modifications?
The vacuum sensor has an electrical connection, which isn't yet available in the BRE system. Do the other connections fit together properly?

alm0st.un1que wrote:

dieselschrauber wrote: ...because there is a suitable KKK original charger (BV43) that easily provides enough power for 210 horsepower. Let's revisit this: Is that the turbocharger from the CR engine? Can you even install it like that, without any modifications? The vacuum sensor has an electrical connection, which isn't available in the BRE yet. Do the other components fit together properly?

For tuning, the corresponding tuner is responsible...

dieselschrauber wrote:

alm0st.un1que wrote: dieselschrauber wrote: ...because there is a suitable KKK original charger (BV43) that easily provides enough power for 210 horsepower. Let's revisit this: Is that the turbocharger from the CR engine? Can you even install it like that, without any modifications? The vacuum sensor has an electrical connection, which isn't available in the BRE yet. Do the other connections otherwise fit together? For tuning, the corresponding tuner is responsible...

Yes, I understand that it's custom software. But what I don't know yet is the function of the vacuum sensor. Will it work as is, or will a connector actually be needed there?
Is this just a position sensor, or is it an electrical actuator? I imagine it might be some kind of combination of a solenoid valve and a diaphragm. If that's the case, I probably won't be able to get the turbo working in my car because it lacks the necessary electronics - right?

I'm not quite able to understand what's written here.
Has only the compressor been replaced, or the entire turbocharger?
Converted from actuator control to vacuum sensor, or vice versa?

alm0st.un1que wrote:

dieselschrauber wrote: alm0st.un1que wrote: dieselschrauber wrote: ...because there is a suitable KKK original charger (BV43) that easily provides enough power for 210 horsepower. Let's revisit this: Is that the turbocharger from the CR engine? Can you even install it like that, without any modifications? The vacuum sensor has an electrical connection, which isn't available in the BRE yet. Do the other connections otherwise fit together? For tuning, the corresponding tuner is responsible... Yes, I understand that it's custom software. But what I don't know yet is the function of the vacuum sensor. Will it work as intended, or will a connector actually be needed there? Is this just a position sensor, or is it an electrical actuator? I can imagine that it's some kind of combination of a solenoid valve and a membrane. In this case, however, the turbocharger probably won't work for me because of the lack of electronics - right?

I also believe that nothing will fit properly after the compressor replacement. You won't be able to make it work anyway, because the pre-tension of the can will no longer be correct either, since the can is now in a different/shifted position on the new compressor.

Regarding the tip from the boss .
The BV43 turbocharger is available with different outlet configurations on the compressor side; you'll need to search for what fits your specific application. You can find them either separately from the exhaust manifold or as a one-piece unit. Simply type "BV43" into Google and have a look.

For control/operation:
The BV43 also comes with a vacuum sensor/control unit; you can leave it connected, as it's better that way. Just don't touch the sensor or linkage, as that will cause further problems. The connector is for the position feedback sensor , and you simply won't use it in your case.

Okay, that was the technical part.
Your biggest challenge will be finding a truly competent "programmer" who can properly configure the engine mapping for this project, ensuring that nothing burns out, melts, breaks, or causes the clutch and drive shafts to fly off.

Here's my two cents on that .

Regards,
Mpire

Thank you also for your replies. Regarding the turbo: As mentioned in the first post, the turbo is identical to the original on the exhaust side, but the compressor (intake) side is from a GT1752V. Of course, this wasn't just a DIY modification; it was professionally converted by the company Holex in Germany, including the engine block and, of course, the correct vacuum sensor, adjusted linkage, etc., so it was delivered ready for installation. It also includes a balancing report. That's why I'm still somewhat doubtful whether it really is the turbo, because if it were, the problem should have started immediately after the conversion. However, I can no longer remember exactly which day it began – definitely not with the turbo conversion, as that would have been noticeable!

Currently, I see software as the least of my problems. I know two people who program themselves and who also provide a significant number of "chip tuners" with files. And I also have the necessary tools for my EDC16.

Next, I'm going to try to analyze Rainer's log – hopefully it will reveal something about any leaks. However, I'm currently very busy and constantly on the move! I will definitely provide updates.

News: Since the leak test was clean, meaning the seal is very likely intact, I took a leap of faith and ordered a new turbocharger – not the standard one, but the "recommended" BV43 from Borg Warner. Apparently, its characteristics are a better match for the vehicle than the GT1752V from Garrett.

In reality: The error has not occurred for a week now!

When fully assembled, there's nothing obviously wrong with the Garrett turbocharger; even checking for "play" by pressing on it with your fingertip reveals very little movement. It's still in absolutely excellent condition. Therefore, I have no complaints whatsoever about the company holex. The turbocharger fits perfectly.
However, to get the modified turbocharger working correctly in this vehicle, it would be necessary to record data such as boost pressure and air mass across the entire RPM range in various scenarios and provide this information to the chip tuner as a baseline. Otherwise, the measured values are unlikely to match the performance curves (even the modified ones).

I have a Garrett GT1752V turbocharger for sale, suitable for vehicles with diesel particulate filters.
Thank you for the tip!

Hi,

Quote:

However, to get the modified turbocharger working in this vehicle, it would be necessary to log data such as boost pressure and air mass across the entire RPM range in several scenarios, and provide this data as a basis for the chip tuner.

No, that wouldn't be necessary and would be completely nonsensical. Creating the VTG pre-tax field is an iterative process with dependencies on other fields. That means you make changes and see what happens. You repeat this process as many times as it takes until the result is correct.
When working with a completely new or unfamiliar charger, it can take almost an entire workday to get it right, especially if "it works" means not just that there's no error message, but also that the response and control are optimal. Depending on how well you need to achieve this, it could even take several days. Therefore, it's logical that this isn't a job for someone who simply pushes buttons, and that it also costs a certain amount of money.

Best regards, Rainer.

Okay, but the approach would have been to transmit the log values, thus saving time because you could then see the deviations from a standard loader.

Thanks for the tip about reconsidering the turbo (though).