Originally Posted by
daleWV
Modern automobile engines with manual transmissions are designed to hold the throttle open slightly and allow the engine speed to gradually decrease when shifting in an effort to keep vacuum from getting too high in the intake manifold which would happen with a fully closed throttle. High intake manifold vacuum tends to pull engine oil past the intake valve guides which then gets burnt in the combustion chamber causing increased engine exhaust emissions. This is part of the emission controls.
but it is not practical, what should I do, nothing?
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View my fuel log 2015 Mirage Intense 1.2 manual: 47.9 mpg (US) ... 20.4 km/L ... 4.9 L/100 km ... 57.6 mpg (Imp)