My vehicle has a manual transmission, and occasionally I'll accidentally lug the engine briefly, when shifting into 2nd gear a little too soon after taking off. When I do this, I hear a sound (seemingly from the passenger side of the engine) that sounds a lot like marbles being shaken inside a metal can.
As soon as I hear this, I immediately take my foot off the gas and down-shift back to first. But, isn't this the sort of thing that the knock sensors are supposed to detect? If so, why doesn't my check-engine light come on? (I have a bluetooth OBDII scanner, and there are no codes.)
UPDATE: I forgot to mention, my knock sensors sit in the intake valley of the engine. I've tried fooling the engine into thinking there is knock by hitting the intake manifold with a wrench, but nothing happened (no CEL, no change in engine noise indicating change of timing.)
Engine is a Toyota 5VZ.