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What are you working on exactly? Looking to change to a different tuning option? I need to do something to tune the DDIM besides slightly larger injectors on the stock ECM and some tightly crossed fingers.
THA and E2 are IAT and a ground. +B is power from the Circuit Opening relay, the other two are the airflow sensor signal. I think EVG is a ground reference for the signal and VG is the actual signal. There's a hard cap on the voltage it can output and therefore the mass of air it can read and that the stock ECM can understand. I think that's 271 grams from the troubleshooting for P0100. 1.1-1.5 volts at idle is a normal reading so whatever airflow correlates with that can give you a basis for what's possible knowing 271 is max. I'm not sure but I suspect the output is a 0-5 volt signal. Since the sensor is calibrated to output a voltage range in a specific pipe size and the ECM only understands that voltage to mean a specific amount of air there's not a way to really 'hack' this by say putting the sensor in a bigger tube (slower air since it's off center so less read that flowing) or swapping a MAF with a different calibration since the ECM is told that 5 volts is 271 grams. I'm not entirely sure how piggybacks get around this limitation, that's something I need to learn more about. I'd like to go MAF-less at some point with a piggyback or a parallel wired ECU. Same boat as you, got an automatic and need to keep the stock ECM for trans.
Tldr, power from relay, NOT ground switched.
THA and E2 are IAT and a ground. +B is power from the Circuit Opening relay, the other two are the airflow sensor signal. I think EVG is a ground reference for the signal and VG is the actual signal. There's a hard cap on the voltage it can output and therefore the mass of air it can read and that the stock ECM can understand. I think that's 271 grams from the troubleshooting for P0100. 1.1-1.5 volts at idle is a normal reading so whatever airflow correlates with that can give you a basis for what's possible knowing 271 is max. I'm not sure but I suspect the output is a 0-5 volt signal. Since the sensor is calibrated to output a voltage range in a specific pipe size and the ECM only understands that voltage to mean a specific amount of air there's not a way to really 'hack' this by say putting the sensor in a bigger tube (slower air since it's off center so less read that flowing) or swapping a MAF with a different calibration since the ECM is told that 5 volts is 271 grams. I'm not entirely sure how piggybacks get around this limitation, that's something I need to learn more about. I'd like to go MAF-less at some point with a piggyback or a parallel wired ECU. Same boat as you, got an automatic and need to keep the stock ECM for trans.
Tldr, power from relay, NOT ground switched.
Attachments
The piggyback will bypass the ecu for anything in regards to the running of the engine. Its hard to explain without showing the harness adapter.
So the main engine running wires do not even end up making it to the ecu as you can see above
2000 GTS Turbo
I won't derail the thread 
Sent from my SM-G892U using Tapatalk
Sent from my SM-G892U using Tapatalk
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