LD 890mbar im Leerlauf & Solldruck wird nicht erreicht? | Posts 16+

dr_braun wrote:

I only installed this ECU last Thursday, and since the weekend (Sunday), the LD problem has been occurring.

It's not that something burst due to the increased boost pressure, or that a clamp came loose, causing the turbocharger to partially feed debris into the engine compartment – if that's the case, it probably won't last much longer!

-> Check for oil leaks on the pipes/hoses between the intercooler and the engine.

@Ulf:

'I've already inspected the printing system, and visually, there's nothing apparent. What's the best way to test it? Do I have a compressor available?'
Okay, let me summarize what we've identified so far: a pressure sensor, a leak in the pressure system, and the hose leading to the pressure sensor. Is there anything else that could be the issue?

stiff/jerky vintage [mechanism/device]
non-sealing AGR valve.

..as mentioned above, the VTG adjustment is fine, and the ARG is set to... permanently .


Best regards, Sebastian.

..so, I checked a few more things today. The turbocharger is working properly, the compressor is running smoothly. I tested the pressure system up to 3 bar relative pressure (4 bar absolute pressure), and a clamp started to leak slightly at around 3 bar. At 2 bar, it was completely sealed. The VTG rod can be moved with a screwdriver, and the hose to the control unit is also fine. Then, I connected the control unit to the compressor and set the pressure to 1 bar (according to the barometer on the compressor). The control unit always showed a lower value than the compressor. I'm not sure which one is incorrect now.
Okay, so I did the DZR test, and I got a time of around 4.8 seconds at 25°C on a flat surface, which is actually a great result. I've logged this data, and I was wondering if anyone could help me analyze this log file, considering the sampling rate.

http://www.mxbikes.de/Log-01.csv



Best regards, Sebastian.

Oops, do you have a barometer on your air pump? Mine uses a pressure gauge instead.

Okay, seriously: I'm not really trusting the pressure gauge on the compressor when it comes to accuracy! Trying to draw any conclusions from that would probably be wrong. Let's say the gauge has a 5% tolerance. In the worst case, if it shows a pressure of 1 bar, the actual pressure might be only 950 millibars. And if you see a reading of 940 millibars in VAG-COM...
Do you know what I mean?

'Yes, I know, sorry about the barometer. I'm completely confused. It's strange because when I disconnected the compressor, the actual pressure was equal to the ambient pressure (979 mbar). After connecting it to the pressure line and starting the engine, then turning the engine off, the pressure was again 890 mbar. Can anyone say anything about the duty cycle?'

Hello Dr. Braun,



How did you bleed the turbocharger system ?

Regards,

Dennis.

"I'm a bit surprised by the duty cycle! Even though the boost pressure differs by about 200 mbar, the duty cycle isn't at its maximum. I can't quite understand that. On the other hand, the measurement interval of six seconds isn't really long either. Perhaps the engine control unit (ECU) deliberately increases the boost pressure slowly in response to significant increases in engine speed (per unit of time) in order to definitely prevent over-revving."

Do you have the ability to create a log recording over a longer acceleration interval (4th or 5th gear, or uphill driving or with a large trailer)? I imagine that the LD (likely referring to a specific system or setting) might not be fully adjusted in that log.

Regards,
Guste.

..into the intake manifold, metal cans inserted into the compressor, then the clamps placed over them, then the hose disconnected from the engine control unit and connected to the compressor air gun, and then it can begin .

@Guste100:

Here are two more very recent logs, one for 5th gear and one for 4th gear (Log03). Unfortunately, it's difficult to test better in the city .
Sometimes it also jerks at 2000 RPM, and above 3500 RPM, you get the feeling that the power drops. It has never been like this before, I can already see that the vacation is over.


http://www.mxbikes.de/LOG02.csv


http://www.mxbikes.de/LOG03.csv

dr_braun wrote:

... once in 5th and 4th gear (Log03). Unfortunately, you can't test it any better here in the city ...

In the city in the fifth to >3000 You crazy But that's your business, to the actual topic:

Okay, there are a few things that seem strange to me. What kind of chip is this? It's surprising that the target boost pressure is already 2250 mbar at 1400 RPM.

Otherwise, I see (using Log2) that the boost pressure is well-regulated and maintained between 1950 and 2400 mbar, but then it starts to decrease gradually from 2500 RPM. The duty cycle decreases only slightly (<5%), which means the engine control unit (ECU) is hardly trying to compensate for the pressure drop (a high duty cycle indicates low pressure).

"In my opinion, the reasons why boost pressure decreases at higher RPMs with nearly the same duty cycle can only be attributed to a bottleneck in the airflow (on both the intake and exhaust sides) or decreasing injection volumes. Could you please perform a 5th gear log with injection volumes and group 11 data?"

"I also recall a very slight leak at the pressure sensor or the small hose *inside* the MSG (manifold), which might have caused the pressure sensor, or its hose (either in the MSG or the engine compartment), to be filled with oil. This could then lead to unusual effects. I think you'll need a mechanical LDA (linear boost actuator). Although I still believe that the MSG should react more strongly to the logged pressure deviations and apply counter-regulation. I'm not clear why it doesn't. Perhaps a different parameter wasn't adjusted on the chip (in addition to the two pressure control maps, there are also the values: boost pressure reporting value 1 and 2, and maximum boost pressure). Do you have the dataset so you can check this?"

You also wrote that the chip was only installed over the weekend. Have you contacted the chip programmer? Do you have a chance of getting the previous state restored (ideally, to a point before your vacation)?

Regards,
Guste.

Hello Guste,

First of all, thank you for your help. I installed the engine control unit (ECU) last Thursday, and everything was fine then. As I said, the problem started this weekend. I've checked the hose leading to the ECU, and it's perfectly sealed and not blocked or anything like that. I can log the fuel injection amounts again tomorrow.
Unfortunately, I don't have a way to get a different ECU or an original dataset, so I need to find a way to fix this. I even went to VW about it, as I used to work there and have a good relationship with the foreman and other employees, but unfortunately, their level of expertise is lower than here .

'Where did this sudden jerking at around 2000 RPM come from? It also occurred earlier during testing (in 5th gear). I'm really at a loss. Can I rule out a problem with the VTG (Variable Torque Geometry) based on the duty cycle? How likely is a pressure sensor defect? What's the best way to proceed now to find the fault?'

-edit- I will check the hose in the MSG tomorrow. Where is the vacuum coming from? -edit-

How old is the diesel filter, actually?

@Rainer K.:

...I replaced it after purchasing the car last fall, and it has been driven for approximately 12,000 kilometers since then.