After installing stiffer aftermarket engine mounts, vibrations between 750-800 RPM can be a nuisance. A common solution is to adjust the idle speed slightly higher using VCDS. This guide will walk you through the process of attempting a Vcds Idle Speed Adjustment and potential reasons why it might not be working.
Understanding VCDS and Idle Speed
VCDS (Vag-Com Diagnostic System) is a powerful diagnostic tool for Volkswagen, Audi, Seat, and Skoda vehicles. It allows users to access and modify various control module settings, including engine idle speed. Adjusting the idle speed can sometimes resolve vibration issues caused by aftermarket modifications.
Attempting a VCDS Idle Speed Adjustment
The typical procedure for adjusting idle speed with VCDS involves accessing the Engine control module (usually address 01), entering the security access code, and modifying the idle speed adaptation value. In this specific case, the user attempted to increase the idle speed from 770 to 820 RPM using security access code 27971. However, despite the code being accepted, the idle speed value (128) remained unchanged. Various attempts were made with the engine off, running, and warm, both with and without the security access code.
Potential Issues and Troubleshooting
Several factors can prevent a successful VCDS idle speed adjustment:
- Incorrect Security Access Code: While 27971 is a common code, it might not be the correct one for this specific vehicle and control module. Consulting the official Ross-Tech VCDS website or relevant forums for the correct code is recommended.
- Software or Hardware Incompatibility: An outdated version of VCDS software or an incompatible cable could hinder communication with the control module. Ensuring you have the latest VCDS version and a genuine Ross-Tech cable is crucial.
- Control Module Limitations: Some engine control modules might have limitations on adjusting idle speed, especially beyond a specific range. The vehicle’s service manual can provide information on adjustable parameters.
- Underlying Mechanical Issues: The root cause of the vibration might be a more significant mechanical issue unrelated to idle speed. A thorough inspection of the engine and related components is advised.
- Adaptation Limits: The engine control module might have learned adaptations that are preventing the idle speed from being adjusted. Performing a throttle body adaptation or resetting learned values might be necessary. This should be done with caution and only after consulting reliable sources.
Analyzing the VCDS System Check
The provided VCDS system check reveals several fault codes related to aftermarket components:
- Radio, Back-up Camera, and Audio Interface Communication Errors: These errors are likely due to the aftermarket radio and backup camera installations. They might not directly impact idle speed adjustment but indicate potential wiring or compatibility issues.
- Passenger Side Mirror Adjust Motor Fault: This fault is related to the aftermarket mirror and is also unlikely to affect idle speed.
- Back-up Camera System Not Calibrated: This error requires calibration of the aftermarket backup camera system.
- Speech/Telephone Audio Channel Faults: These are likely related to the aftermarket radio and indicate short circuits in the audio wiring.
Conclusion
While adjusting idle speed with VCDS can sometimes mitigate vibrations, it’s essential to ensure the correct procedure and address any underlying mechanical or compatibility issues. The unsuccessful adjustment in this case could be attributed to an incorrect security access code, software/hardware incompatibility, control module limitations, or the need for adaptation resets. Further troubleshooting and consultation with experienced VCDS users or automotive professionals are recommended. Addressing the existing fault codes related to the aftermarket components might also be beneficial in resolving the overall vehicle health.
