I was replaying my logs tonight on my newly turbo'd honda and notice that the knock sensor likes to shoot up to a value of 25 (saw 48 once!) when you release the throttle after a pull. What I noticed is that the ECU adds instant advance, jumping from about 16* to 38* when you release the throttle. Is this false knock or is there some merit to this issue? Last thing I want is a broken motor...

 

Thats false knock. You need to realize the knock sensor records all the noise from the motor and there are alot of things besides knock that get detected by the knock sensor. For example VTEC activating and the wastegate opening can cause knock spikes. I wouldn't pay attention to any knock detected that wasnt during heavy load.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">Thats false knock. You need to realize the knock sensor records all the noise from the motor and there are alot of things besides knock that get detected by the knock sensor. For example VTEC activating and the wastegate opening can cause knock spikes. I wouldn't pay attention to any knock detected that wasnt during heavy load.</TD></TR></TABLE>

I understand what you are saying, but Im still not sure if its false knock. Heres the scenario: Im going full throttle, and nearing redline, I completely release the gas pedal, causing the throttle plate to slam shut. The ECU responds to the quick change in manifold pressure by advancing the ignition timing from 16* to 34*! However, could there still be increased amounts of air in the combustion chamber, causing high cylinder pressures, which under a high amount of advance, lead to knock?

I guess what Im asking is does anyone have experience with the stock knock sensor on a STOCK motor giving false readings under certain conditions? If so, what conditions, etc.?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">For example VTEC activating and the wastegate opening can cause knock spikes. </TD></TR></TABLE>

Lol, well those were two examples, werent they! Good post, Im just playing the better safe than sorry position and want to be absolutely sure Im not knocking. Definitely no audible knock and the plugs look clean, but I havent been able to get a super clear cut answer on what exactly implies knock on a plug either...