One thing I’ve been meaning to fix up is my apexi RSM since going single turbo and aftermarket ViPEC V88 ECU.
I used to splice the Apexi RSM RPM wire to the IGF wire on the stock loom as per the Apexi Manual, this gave me a RPM reading on the Apexi RSM without any issues.
The stock 2JZGTE ECU uses a IGT and IGF ignition signal – basically the IGT sends signals from ECU to igniter and IGF sends ignition verification signals from igniter to the ECU – to confirm ignition spark which allows the ECU to enter fail-safe or limp-mode if there is a problem. There is a good writeup here on how the whole system works for different Toyota ignition types for more technical info –http://www.autoshop101.com/forms/h23.pdf
The ViPEC (and most other EMU’s) don’t need the IGF wire function, so it’s not plugged into anything usually.
Now with the ViPEC in and no stock ECU I hooked the IGF wire directly to the Apexi RSM (Not plugged into ViPEC at all). I’m now getting an RPM signal on the Apexi RSM, so anyone wanting to use the signal for RPM can if their tacho device uses the stock IGF signal location.