[arunphilip]

Originally Posted by Acharya

Does it really work in this fashion? As far as I remember, manufacturers have certain quality standards, quality checks are defined on these standards. A unit either passes the tests or fails it. In fact, in sample testing whole lot is expected to be scrapped even if few units are found to be faulty.

It may not happen in the mechanical side of things, since the mechanicals of a DSG gearbox are tried and tested, and are pretty much a standard mechanical gearbox. It is definitely possible on the mechatronics side, specifically the electronics. And its the mechatronics unit that's been the most common failure point in the DSG/DQ200 gearboxes.

Companies like Intel, Nvidia, AMD all use product binning where chips with a limited number and specific pattern of flaws are sold as a fully-functional lower-end product, or chips that show instability at the extremes of testing are sold as a lower-end product. For instance, the most stable Intel i7 chips are what are unlocked for overclocking and given the K modifier, chips with flaws in the L3 cache are binned as i3.

Similarly, it is very possible that the electrical testing of the mechatronics unit will define a 'pass' if the behaviour is within specific tolerances. For an example, let's assume that the output voltage should be within ±5% variance when input voltage is 12V for the unit to be passed. Now, there's nothing that prevents VAG from specifying that units with ±1% variance goes to Audi/Porsche, ±1-3% to VW, and ±3-5% to Škoda.

All of these units are still 'passed' units, but its not a binary pass/fail, its 50 shades of gray .

Now, the original pass tolerance of ±5% would have been arrived at based on some factors which mean that those tolerances will never be approached or exceeded.

However, out in the field, how often are these systems pushed to the extremes is where these tolerances start making a difference. And that's where it appears that the DQ200 gearbox runs much closer to the edge than VAG intended - not only are the engines limited to the maximum torque the gearbox can handle (by design), but other factors like ambient temperature, etc. all reduced that inherent safety margin, to the point where variations in individual mechatronic units cause them to fail at a far higher rate than was intended.