This article details the process of adjusting the camshaft timing on a TDI engine using VCDS (Vag-Com Diagnostic System) to achieve the correct torsion value. A significantly retarded camshaft was impacting performance, making the car feel underpowered. Through careful adjustments and monitoring with VCDS, the torsion value was brought within the optimal range, resulting in a noticeable improvement in engine response and drivability.
The initial VCDS reading showed a torsion value of -5.9 at idle and -6.4 while driving, indicating significant retardation. Since the camshaft rotates at half the speed of the crankshaft, a camshaft adjustment of approximately 3 degrees was calculated to correct the 6-7 degrees of retardation observed. A digital protractor was used to ensure precise adjustments.
The first adjustment of 3 degrees brought the camshaft bolt heads closer to the center of their slots. However, the VCDS reading still showed retardation.
Subsequent adjustments of 1 degree and then a fine-tuning of 0.25 degrees were made, using the digital level for accuracy. The final VCDS reading showed a torsion value of 0.5 at idle and 0.0 while driving, bringing it within the desired range marked on the timing belt cover.
After a test drive, the improvements were significant. The engine felt more responsive and powerful. While the long-term impact on fuel economy remains to be seen, the immediate improvement in drivability was substantial. The idle fuel consumption increased slightly, but this isn’t necessarily indicative of overall fuel economy changes. Further observation and fuel consumption calculations will be necessary to determine the long-term effects.
A question remains regarding the torsion value indicated on the timing belt cover: does this value represent the ideal torsion value at idle, or under a different operating condition? Additionally, an assessment of the Injection Quantity Deviation values is desired to further evaluate engine performance after the adjustments.
