Oil Consumption After Highway Driving

Vehicle: Skoda Octavia II Estate (Wagon), 2012, 103 kW / 140 hp, engine code CFHC.

Hello everyone!

"Recently, the oil level in my Octavia has been increasing. After some research, I thought it might be due to active diesel particulate filter regeneration. According to this, the oil level should decrease after a fast highway drive as fuel components are released (at least partially). So, I initially lowered the oil level by removing 0.3 liters to bring it to the maximum mark, and then I took a trip of about 50 km on the highway, driving as quickly as legally allowed and traffic conditions permitted. The oil temperature remained between 88 and 96 degrees Celsius. Then came the unpleasant surprise: there was again 0.2 liters too much oil. Therefore, it cannot be due to diesel particulate filter regeneration. Also, I mostly drive longer distances. Furthermore, the diesel particulate filter warning light illuminated once and eventually turned off on a short trip without any special regeneration driving. Otherwise, the engine runs perfectly fine."

Do you have any idea what might be causing this? Are there other ways to troubleshoot and narrow down the source of the problem?

Regards,
mcGregg

Wasn't there something about tandem pumps with leaks that caused this type of error?

Is the (CHFC) an EA 189 (which is a CR type)? If so, it shouldn't have a tandem pump or PD elements.

If there's an increase in oil pressure, especially a drastic one (although I'm not sure if you've checked the cold oil levels on the same horizontal surface before), it can only be caused by an injector that is constantly leaking.

Are there any measurements available?

matthiasTDI96 wrote:

The (CHFC) is an EA 189 (which is a CR), correct? Therefore, it should not have a tandem pump or PD elements. [...]

Absolutely correct.

Here are the measurements (hopefully they are correct).

I wouldn't necessarily consider the rail pressure calibration points as an indicator of a fault (my interpretation: they show the time at which specific rail pressures are reached during the injection cycle and are used to correct the injection durations).
The values for the variations in fuel injection amounts at idle would be just as informative, and perhaps also the control times/start times of each individual injection.
If a nozzle is not sealing properly, you can usually tell by looking at the appearance of the nozzle (specifically, the part that needs to be removed) in addition to checking the LL values.
hg
Herbert.

Hello Gregg,

If you compare the calibration values with those of other users (see here: https://community.dieselschrauber.org/en/viewtopic.php?t=28779),), then I would claim that your nozzles are leaking and dripping.

Does the exhaust smoke blue/black? It could also be due to modifications, especially if the fuel rail pressure was increased using a resistor.

Hello everyone!

Thank you for your insightful answers. If I understand correctly, excessive oil consumption in a CR diesel engine like the 189 can only occur due to extreme and frequent short trips (which is not the case for me) or defective injectors. Yesterday, I drained another 0.2 liters; at 102600 km, the level is just above the maximum mark. At 99300 km, the level was still at the maximum (without draining). Therefore, I have experienced an oil increase of 0.6 liters over a distance of 3300 km. I now suspect a defect.

The strange thing is that the engine runs perfectly fine, and I'm quite sensitive to any issues with it. I will now contact the seller; I still have a warranty. Thank you again for your help; now it will be harder for him to dismiss my concerns.

Regards,
mcGregg

Quote:

if you compare the calibration values with those of other users (see here: https://community.dieselschrauber.org/en/viewtopic.php?t=28779),), then I would claim that your nozzles are leaking and dripping.

Please enlighten us about what exactly you are basing this on. To me, the values seem to fall within the range reported for R4 engines in the link provided. I don't think we even have clarity regarding the measurement principle. For example, calibration point 2 sometimes appears before calibration point 1.
hg
Herbert.

Hello Herbert,

I'm afraid I have to agree with you. That was nonsense. I've just realized that.
that the calibration values are used much less for determining the actual quantity limits, but rather to smooth out pressure fluctuations in the system.

There is a doctoral thesis that I am unfortunately not allowed to publish here, which shows that the adjusted pulse duration achieved through calibration only corrects for pressure waves. In other words, it smooths out pressure waves.
This all happens within the range of 0.001 milliseconds.

For those who are interested: You can find information on this topic under the title "Injection Quantity Correction in Common Rail Systems Using Magnetoelastic Pressure Sensors."

According to my research, actuation times (from the control unit) of up to 1.4 ms are considered normal.
Corrections like the one mentioned above, such as an injector time of approximately 0.040 ms, would therefore not be dramatic.

My knowledge in pneumatics is not sufficient for validation; that's a more advanced subject.