arran

Hi all,

Can anybody provide any feedback on how the DIY autotune knock sensor circuit here:
MS3 Knock Module Kit DIYAutoTune.com
works with the S5 89-91 RX7 factory knock sensor?

13bdarren

I have not trying the new module yet. I wish to in the future for idividual rotor knock. I am using this kit with the stock sensor and it seams to work excellent. I have it wired into the ms3 and it is setup and working good. Pull timings when it detects knock. Knock gauge for detonation sensor klopfsensor NEW | eBay

First gen man

iTrader: (24)

I am about to order it and try it out with the factory knock sensor, no one has tried it out before?

Aaron Cake

iTrader: (1)

It will work fine...however, the FC knock sensor is tuned to only detect knock in a specific RPM range as it's a resonant and not a full band sensor. As I recall (and this is from memory, so it may be a little off) the sensor is sensitive around the 3000 RPM region because that's where Mazda determined the engine most likely to knock. Above that range, there is too much other noise.

So upgrading to a better sensor would likely be the best bet. Then you can tune the filters in the MS3 to recognize knock on a sensor with a much wider range.

Or, tune to avoid knock.

First gen man

iTrader: (24)

You always gotta tune for a safe AFR and safe ignition, but I love setting up these "AFR safety" settings and "knock ignition retard."

So after market sensor it is? Anyone know the thread type on factory knock sensor?

rxspeed7

iTrader: (5)

The rx8 uses a nice full range sensor iirc.

Aaron Cake

iTrader: (1)

I think the thread is just M8 x 1.25. But really, it's whatever you tap it out to be.

Tuning knock isn't trivial though. Everything is critical including the position of the sensor. Find out where the sensor is located on the RX-8. If Mazda moved it, then there's a reason.