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View Full Version : Which knock count is right?


x-pride
07-30-2005, 02:16 PM
My super AFC 2 says I have a knock count of 14 while my MMCD software/pocket logger say I have 0 Knock at idle. So who do I beleive? This is on a 1g AWD with a 56 trim.:D

Kracka
07-30-2005, 02:38 PM
Listen to the logger software, the AFC2 knock thing isn't compatible with DSM's.

niterydr
07-30-2005, 03:17 PM
Listen to the logger software, the AFC2 knock thing isn't compatible with DSM's.
Well you can use it, but is a PITA to setup properly with the dsm's.
So like chris mentioned, always trust the logger over anything else for information.

LightningGSX
07-31-2005, 05:38 AM
1G knock sensors are a broadband type(basically a piezo microphone), with makes them totally worthless with the AFC, regardless of setup procedures(unless you want to add a bandpass filter, amp, gated integrator, etc).Further more, the voltages are so small, depending on the input impedance of the AFC, it could be interfering with the ECUs knock circuit, making even your logged knock sum from the ECU false.I would disconnect it immediately.

2Gs on the other hand used a resonant type knock sensor, which means the sensor itself is designed to resonate with the knock frequency of the engine, which adds a large amount of energy to the output at the engines knock frequency.This may be of some use to the AFC, but I doubt you'd be able to actually interpret knock without any empirical baselines.Again the unknown input impedance of the AFC could still lead to false readings at the ECU, but less likely than in the 1gs due the the higher voltages involved.