Info on knock tables, knock conditions

[MagicMike]

Hi guys,

I have recently re-installed my engine (Z32 vg30dett), and something has gone skew with my knock sensor, giving a code 34 constantly.

I know for a fact that I am not knocking. My question is around what the ECU does with the code 34. I can see it accessing knock fuel and timing maps, but does it do anything else?

So knowing that my tune is safe, and not wanting to pull the engine again just yet just to fix knock sensor/wiring, if I copy the fuel and timing maps over the knock fuel and knock timing, will this effectively duplicate my normal operating conditions? Or is there something else the ECU does when it is seeing a 34?

I should ad, I have a knock sensor bypass plug coming (resistor in a plug), but in the meantime I want to get around the performance reduction.

[Matt]

When the ECU knock sensor fault code is active
- Fault code (34) raised
- Switches to knock maps
- In the flagged area of the timing map will retard knock (normally 5 degrees)

You can disable the knock flags in both timing maps to remove the retard

[MagicMike]

Great! Thanks Matt!

[UNISA JECS]

Hi Matt this same question raised by the OP, now what about on OBDII Type 4 board (B14 1M871 M/T) where the entire maps are highlighted IIRC you cannot disable the highlighted areas, how does it work for these ECU's and is there a way to actually disable the knock sensor all together via Nistune?

[Matt]

You are thinking the O2 flag is over the entire fuel map (value 128 = O2 feedback flag on these later model ECUs, anything higher it is just a normal fuel value with no feedback)

Timing maps on B14 only have knock cells set on the right end

1. Feedback switch 1: Knock analysis (untick)
2. Disable knock flags in timing map (K button)
3. Not possible to delete the knock sensor fault code in OBD-II compatible ECUs (this was removed by Nissan from 1995 onwards for OBD-II capable ECUs)