MoTeC Global Forum

Hello,

I have a M800 and have fitted a J&S safeguard unit .
This is a gated device using ECU triggers and has individual closed loop knock control .
I would have preferred the SKM to keep it all Motec but I could not justify the price.
Just want to protect my big $ engine against the unexpected.
I would really appreciate some help on setting up and data logging the output data signal from the J&S unit which is a maximum of 1.3vdc in 10 x 0.13v steps.
I can set up a user defined custom table 11 x 2 resolution starting at 0v for 0, 1 for 0.13v , 2 for 0.26v etc with a 200hz sampling rate.
Can I set it up in Adjust/sensor setup/input setup/other/knock voltage- input source AV4 with a custom table as above.
How do I activate it from here ...??
I want to data log this against O2, rpm ,TP, Boost, Ignition Advance etc so I can road tune it better and basically am a very eager amateur.

Any tips on setting this up would be greatly appreciated.

Mike

I see no outputs other than the ignition in to ignition out.
As the unit does its own control, maybe use that as is?

If it actually has an output, the you would need to get this into the ECU either as a single analogue voltage or if the individual cylinders then into n*analogue inputs... Looks like 8 inputs into the M800.

I've done this before, used an input with .001v resolution as the input channel to Knock Voltage. Its impossible to be able to discern individual ign channels, but at least you can tell what areas of the ign mapping need adjustment. There will be a small ground offset between the two units, so .13v per degree won't be exact, log the Knock Voltage when no activity is present, there will be a small -v or +v present, use this value to write a math in I2 to report Retard in Degrees. This can be overlayed in I2 against all your other channels to determine where adjustments are needed. While not as refined as an SKM you can get it to do what you want.

Holmz- The J&S unit has a single analog output for a gauge (LED display), this is what he is using as a Knock Voltage input. John has some info out on how to interpret the gauge signals.

Thanks for the suggestion, that's exactly what I want to do, now I just have to figure out how to set it up.
Steep learning curve.
Any more advice is most welcome and appreciated!!

Don't just concentrate the trimming on the main ign table, utilize the many comps available, like ign vs ground speed (and load), or ign vs gear, or ign vs AIT (and load).

Oh and another thing, with the J&S you will see false knock activity when in low gear under very high accel rates such as sudden loss and regain of traction or active TC/LC or drivetrain 'windup', don't worry about it, consider it a feature.

Thanks for all the good advice and tips.