Plex Knock Monitor Install

Hello Everyone. Hoping someone can offer some assistance . I am in the process of installing a Plex Knock Monitor Dual sensor on my Twin turbo Mustang.

I would like to wire the monitor to be able to detect knock per cylinder and am not sure how to get the number 1 cylinder reference. Ecu is a Bigstuff3 .Points wire from Bigstuff Ecu harness directly to Msd 7al 2 analog box. If it matters, this is a crank trigger setup and using the distributor as the cam sync. Any suggestions? Thanks in Advance

Need a little more detail on your setup Nelson, are you using the distributor just for cam sync, or does it distribute the spark to the cylinders too? A quick look at the documentation on an MSD 7AL 2 would make me thing you're just running the one coil and using the distributor to send the spark where its needed?

If that's the case, I'd try to see if you can get the BigStuff3 ECU to output a pulse on an IO pin that corresponds to cyl 1 firing, as there isn't a way to get the information out of your ignition system.

Do you have to stick with a distributor for race class rules or similar?

Thank you for the prompt reply. That is correct Zac. Using the one coil and distributor to distribute the spark to each cylinder. I was hoping I could get a signal from my ignition system but I guess that is not possible. I will look into picking up a reference point from the ecu. This is primarily a street car, so no class rules dictating my choice of trigger system . What did you have in mind?

Block off the top of the dizzy, but keep the sensor inside it in place for your cas pickup (have to make sure its locked, so no mech or vacuum advance), and go individual coil :-). I'm not too sure what the BigStuff3 ECU's are capable of though...

:) Had a feeling that would be your recommendation. It is an option with bs3 to upgrade to cop, but not something id like to entertain at this time. The distributor is currently locked out in this configuration. The cam sync signal informs the ecu of the position of the number 1 cylinder and provides a signal to the ecu once per 360 degrees of cam rotation. after the cam sync signal, the next input received by the ecu is the crank signal from the crank trigger. There is a 2 wire connector for both the cam sync and the crank trigger which connects to the bs3 wiring harness. Any Thoughts?

I'm not sure if the plex will be able to read the VR signal your dizzy will be outputting, I need to have a quick read of the documentation. Will have a look at lunch lunch. If it can, you might be able to get it working with your distributed setup after all!

Have my fingers crossed! Thanks for the help

Hmmm, the instruction manual, http://www.plex-tuning.com/instructions/KNOCK_Instructions_V2/Knock_Monitor_Instructions_Manual_V2.0.html doesnt list a vr sensor as being an option for the trigger input, but I'd give it a go anyway. Wire the red Trigger + wire to the +ve side of your VR sensor in the distributor, and the black Trigger - wire to the -ve side of the vr sensor in your distributor. Select 'falling' as the trigger edge option, and 8 as the number of coils (even though its really only one). Do you know when the cam sync pulse happens in relation to cyl 1 firing?

Thankyou. I will give that a shot. I know that the cam sync pulse happens roughly 15 degrees before the crank signal from the crank trigger