G4X as data logger

[Eric S]

Is it at all possible to use G4X to data log factory ECU's behaviour? Specifically I'd like to log below signals;

• SGT and SGC (MX-5 NA6/8 CAS) signals - TRIG1, TRIG2
• Engine speed (rpm, deduced by G4X from CAS signal)
• Battery voltage (already logged by G4X)
• TPS (volts) - AV1
• ECT (volts) - AV2
• MAF (g/s) - AV3
• IAT (volts) - AV4
• Injector 1 duty cycle (ms) - DI1
• Idle air control valve duty cycle (%) & frequency (Hz) - DI2
• Ignition 1 trigger timing (ms) - DI3
• Link CAN Lambda

Makes me wonder if a buffer is needed between passthrough/breakout PCB and G4X in case the input impedance of G4X inputs affects the signal (ever so slightly) for factory ECU.

[Adamw]

All of that would be no drama except for ignition timing would not really be possible, no buffers needed. 

Not sure what you hope to gain from it though, the factory tune is designed to meet emission requirements with acceptable economy and many compromises to allow safe operation in a large range of environmental conditions and operating conditions.  When fitting an aftermarket ecu the goal is generally better performance, there are usually no emissions considerations, the environmental conditions are limited to your local area with fuel you know and the driver knows the operating conditions it will see.