When using VCDS for diagnostics, you might encounter discrepancies between “Specified” and “Actual” values in measuring blocks related to vacuum. For instance, at idle, a specified value of 1040 mbar and an actual value of 989 mbar are considered normal. This slight vacuum in the intake tract is expected and doesn’t indicate a problem.
This minor deviation (51 mbar) is insufficient to trigger the ECU’s closed-loop corrections, which typically activate around a 200 mbar difference. Essentially, the ECU doesn’t consider this small discrepancy significant, especially at low load and RPM.
Similarly, an actual value of 1200 mbar against a specified value of 1100 mbar during open-loop operation doesn’t warrant concern. The ECU isn’t making corrections in this range, as this operating region doesn’t demand extremely precise tolerances. Worrying about these minor differences without additional symptoms is unnecessary.
To thoroughly assess the actuator and overall turbo function, conduct a VCDS logging test with a partner while driving. Accelerate at full throttle from approximately 1500 RPM to 4000 RPM in 3rd gear.
Log Measuring Blocks Group 11 alongside Group 1 (for relative power reference) in VCDS. This data will provide crucial insights into the health of your turbocharger system.
The Basic Settings function in Group 11 primarily resets the baseline offset for diagnostics. While helpful after installing a new turbo or reflashing the ECU, it doesn’t offer detailed performance analysis like the logging test described above.
