When our Knock sensor registers knock how much timing does the ecu pull back? Will it go from positive advance to a negative degree? I was just studying my timing logs and was wondering as it is usually between 5 and 40 but has an instance about once every 50 trips where I will see a -2 or -4.

 

Anyone?

 

The stock PCM is usually pulling timing at all times, when viewed via the OBDII data list. How much it pulls is based on knock sensor feedback. There is no documented info from honda how the ignition timing logic operated, or what the advance/retard curves look like.

 

Thank you. I was just curious.

 

i have never seen timing retarded to the point where it is negative. I would think that the engine would be hard pressed to continue running if it was only starting the combustion process once the power stroke had already begun

 

The PCM pulls timing most all the time, so it is displayed as a -#.

If the timing map is supposed to be 20deg+, and the PCM pulls -deg from knock sensor feedbak, it's displayed on the OBDII datastream as -2.