Hi I have just purchased a 1.6 auto duke 64 plate and I am worried may have purchased a duff. The car so runs fine, but at around 30 mph there is a definite 'pinking' sound but only on acceleration. I have taken to mechanic who could not explain the source and suggested Nissan dealer. Nissan took car out, and say sound totally normal as is cvt gearbox. I just wonder if anyone could kindly confirm is this right.? Not sure how such a strange noise could be 'normal' thank you