knock sensor detects too much ?

[landybehr]

Hi,

I have knocksense on my Rover V8. I´ve gotten used to it detecting knock above 3000Rpm regularly - even though AFR and Advance are very similar to those of other users. So probably that is just noise. While the instructions recommend to turn the tune-resistor 15-20° away from that position that will provide a signal at idle, that 3000RPM signal will still be there when the resistor is turned 45-60°
? Is it common for engines to need the sensitivity being reduced that much ?

No problem - I tell MS not to listen to knock above 3000RPM. That´s operating condition that I rarely see anyway and I stick to known working map-values there.
But many times (not always I think) I have a signal at 2050RPM and around 80kPa. And a cold engine makes that worse, while it seems to not be present very often with hot engine. I have reduced the advance by 5°, even though I haven´t been very far off from values that work for other people. I do change the lower kPa bins a lot and go lean there. But THAT point where the knock occurs is not my tuning focus. And a very cold start causes a short flash of the knocksense LED, while hot start is ok. That could have sth to do with my cranking and ASE enrichments though.
? Does it make any sense or explain anything that knock is more present when the engine is cold ? Is there a likely explanation ? Like the sensitivity of the sensor still is too high. Or VE´s are too low (which may be right for cold running, but they are MLV-tuned and the car drives fine when cold)

I cannot hear knock. But that does prove nothing. The vehicle is very noisy (tyres, gearbox) while the engine bay has good sound proofing. And not sure I would notice knock if it were there.
? is there a way to prove the sensor detects knock correctly ? Like a certain save! engine load and RPM at which I could advance progressively ?

[zerofloat]

On a cold start (like 20F) my knocks sense sees a knock too and flashes. It's OK after warmup. I'm guessing it's caused by the clearances in the engine being different than when at operating temperature. It hasn't blown up yet anyway.

[landybehr]

Hi zerofloat,

thanks a lot - being grateful for every piece of input !