need some info on knock sensors

[Matt82]

how is it they actually work? my car gets its timing noticably knocked back between 2-3krpm, i doubt it should be doing this at all.

can someone let me know what causes it (so that i may try to cure it)

and also, whats the principle behind a knock sensor, as i think i may have a pair of duff ones

 

[Matt82]

thats what i beleived too.

i had mine off today. there are two. the one on the gearbox side is easy to get to, the one on the off side is a mission. i had to get the alt off and belt tensioner. seeing as ive done the water pump before, it was an easy job.


i did some reading to see what else i could find out. the sensors need to be torqued to 20nm.

mine were miles tighter. took them off, cleaned them, reassembled to correct torque and took it for a run.

i think it may have been cured. it has a lot more urgency when it pulls, i hear there is no way to test them without a scope tho