Autosport Labs

Is there a way of the mjl detecting a voltage signal? as in, supplying a voltage to it so that it effected the timing?
I know there no provision of a knock sensor yet, but i wonder how difficult it would be to fit a sensor and get it to control the mjl when know is detected?

From what ive read, knocking (pinking) has a frequency of about 5KHz. most of the knock sensors ive seen are piezoelectric (i guess this mean a voltage is produced at 5KHz?

is there a way of taking this voltage and feeding it into mjl and then getting the mjl to reduce the timing by a few degrees

could this be accomplished by an external unit? say something that receives the sensor signal and then tricks the mjl into thinking its supply too much advance and so the mjl would then reduce it to the advance thats in the table? (you could make it think its say 3 degrees too advance and so mjl would actually retard it by 3 degrees)

does this sound at all feasable?

thanks for any feedback!

With the current hardware and firmware, you could have an external signal switch the controller to the secondary map, which you could designate as the 'safe' map. If this was used to detect 'knock' then all you'd be able to do is detect 'knocking' or 'not knocking'. Additionally, an external sensor or unit would need a clean on/off output to activate the MJLJ's option switch.

That said, I think the above approach is so primitive that it wouldn't be worth doing.

An alternate approach would be to use the AUX input on the MJLJ board. this input is tied to one of the Analog - digital inputs on the processor. The popular GM knock sensor and necessary amplifier/detector module could be used to feed this input- likely with some signal conditioning to match the 0-5v input requirements of the processor.

It would also require firmware changes to implement the necessary algorithm to read the input and pull back timing when knock appears-- and restore timing when knock goes away. Not to difficult, in principal.

However, what complicates this is that the popular GM knock sensor is likely tuned to the engine it was designed to fit. Does the knocking of your engine sound like the knock from a pushrod V8?

Hope this helps.

I see what you mean Brent, thanks. i was just curious as to what could be done before the next generation of boards/ firmware was available (primarily to aid tuning of a forced induction motor).

Here in the UKmany Vauxhall/ GM and even Fords used knock sensors (and most of their engine are 4 cylinders) so they might be more compatible or more likely to work. maybe even a sensor from a couple of different types of engine so that you had more chance of detecting it.

thanks for your thoughts.