knock sensor detects too much ?
Posted: Sat Feb 21, 2009 1:17 pm
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 ?
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 ?