Had the FD2 on TDI South's hub dyno on Tuesday for some changes to the map to improve fuel economy at part throttle. To cut a long story short, when the car was dynoed pre-mapping, it mysteriously seemed to be making a few horsepower less across the rev range than when it was mapped back in December, yet nothing else has changed.
A number of possible explanations were put to me, one of which was that if the car had been over revved, the timing chain might have slipped a tooth, putting the cam timing out, especially if the chain has stretched of the tensioner is not up to the job. However, since December to now, I haven't been aware of any power drop and although I have done a couple of mishifts, I don't think I've strayed over the rev limiter. Also, the chain is still quite fresh and I'm using an uprated Toda tensioner. Has anyone had experience of jumping a tooth on the timing chan and if so, was the loss of power noticeable?
Other explanations offered were that the engine is suffering premature wear but I doubt this as the engine only has 36,000 miles on the clock, is serviced religiously (oil change with 5-40 fully synthetic every 3,000 miles), has never been tracked, has never been allowed to run low on oil and is driven with plenty of mechanical sympathy. Any feedback or ideas would be much appreciated