OK. Have done a search knock sensor and hit 217 pages of sensor stuff - looks like there is also a sensor forum I should look at. I am looking at doing an EDIS MegajoltE on a knock sensor equipped engine Subaru EA82T from the mid 80's L Series.
I have monitored the output of the knock sensor to know that it does work, just not very often which may be due to the fuel LPG rather than the driving and 12psi of boost
IT had only occurred to me that I would need to investigate the Megajolt regarding knock sensing before I dream any further for my turbo application anyway.
Can the Megajolt E be rigged to knock sensor one wire or two wire ?
What have others done to deal with knock sesnored engines ?
thanks
looking at EDIS on a flat four Subaru family EA81 and EA82
Don't seem to be many responses on here right now.
I guess Brent is busy?
Spam in the General Discussion area too! So not sure how active this place is anymore.
But perhaps I can help?
From what I know. Knock sensors feedback a voltage dependent on the amount of knock.
This a value 0-5v.
Megajolt can be configured to read 0-5v via the aux input.
I think you need to make a hardware change. It's in the 'manual'.
But with that done, you should be able to retard the ignition depending on the voltage value read.
The Megajolt can *receive* an input from a knock sensing system, if it can output a voltage proportional to the knock. See the auxiliary map table in the wiki for a way to override the ignition map - typically used to retard the ignition.
Look at the J&S Safeguard system for a universal system that can read engine knock.
Hope that helps, let us know if we can help further.
Brent Picasso
CEO and Founder, Autosport Labs Facebook | Twitter
Looking at the date, no wonder I didn't reply to this. I ended up in intensive care ward when pneumonia tried to finish me off , two weeks later.
Well this keen bean is back and getting closer to the install , possibly only using its factory knock circuit to indicate if I can.
It is 1985 Subaru EA82 turbo. The knock system has 5.0 V at IGN ON - engine off. Once running , it is at 1.7V, as this rises towards a max of 4.5V the KCM under the dash and the 4 pin module in the Hitachi dizzy , pull the timing back in steps. I run a Volt meter panel in-dash reading off the diagnostic wire of the factory system. If I hear a knock, I can see above 1.7 on the panel. Or, if squeezing it a bit , somewhere above 5000 - 6500 and feel like a fuel cut on the LPG, look down and see the volts have gone somewhere in the 3V plus range. Back off, things are fine. The fuel system is essentially Impco L and 200 mixer, capable of running a 351, but very common on 4.0 litre Falcon six in Oz. I run this on 1800cc just fine. Also run in- dash O2 reader gauge to monitor the story.
Looking forward to it all running smoothly once EDIS and MJ/E MK2 are running
