This isn't really a question, but I thought I would post this here for anyone who has similar problems or uses the search bar in the future (there should be enough key words in this so it pops up in search results, this will save me replying to other threads). My car was having a few issues: -Very high current draw when switched off (850milliamps/0.85amps). This was draining the battery very quickly (even my Optima deep cycle was struggling). I plugged my multimeter in series with the battery to measure current draw and started pulling relays/fuses. It turned out that the Ignition Coil Relay and EGI (ECCS) relay in the engine bay were constantly energised with ignition off (you could hear the relays click/energise as you removed/replaced them). With these relays pulled out the current draw with ignition off returned to a normal value (about 35milliamps). So while I was busy studying the wiring diagram trying to figure out what was wrong, I would just pull out these relays whenever I parked the car to avoid draining the battery. -Hard to start sometimes (I think this is related to the battery being discharged). Gradually a few more problems popped up. -Idle problems - car would idle for about 30-40secs then switch off. This was very repeatable (occurred almost all the time at traffic lights when the car was at operating temp. If I just stabbed the throttle as it was about to stall then it would idle for another 40secs then try to stall again. -Fuel pump running constantly when key was at ignition on with engine off (should only run for 1-2secs with engine off). I wasn't really sure what was causing the 3 other issues but I wanted to fix the current draw issue first because it was annoying having to pull out the relays all the time. So after studying the wiring diagram I could see that both relays shared a common trigger, pin 16 in the ECU. The ECU grounds this pin when you turn the key to ignition to energise the relays. So I either had a short in the harness or something in the ECU was causing a short to ground in pin 16. We tested continuity b/w the relay sockets and the harness connector at the ECU for pin 16 and found no issues in the harness (it was new OEM and I never had this problem on my old harness so we wanted to make sure there wasn't a short in the new Nissan part). Then we pulled pin 16 from the harness out of the ECU connector which stopped the current draw and de-energised the relays. So this pointed to the ECU being at fault, which we double checked by swapping to another ECU. It's also worth mentioning that the red light on the ECU was always on with ignition off, my understanding is that this light shouldn't be on unless the ignition is on. After swapping ECU's the light stays off with the ignition off. So finally I bought a replacement ECU off another member, had my tuner swap the Nistune board over, and installed it into the car. Turns out the idle issues and fuel pump running issues are now sorted too, not sure if there were other faults in the ECU that were causing these issues or if they are also related to the pin 16 short. My tuner also ran the car on the dyno to make sure everything was still ok and it's fixed a few little bumps/dips in the dyno graph too. I can't really say what caused the fault in the ECU, it has been in and out of the car a few times during tuning/socketing so it may have been due to that. I haven't checked the ECU circuitry yet with my multimeter, but there were no obvious burn marks on the board. Hopefully this will help someone else with similar issues and also encourage people to read the wiring diagrams. They look complicated but you are only dealing with a few wires at a time so it isn't as hard as you think it'll be.
