I have a 2005 G35 coupe with a VQ35DE and auto trans with a recently transplanted motor. Engine will start and idle like a champ. If I rev in park, under light throttle, no problem reaching limiter. WOT will rev to 3k and start misfiring, bogging down. Will drive down the road but is very sluggish and struggles to pull hills.

Noticed that the battery will not hold a charge. A fresh, new battery was killed in a matter of hours. Measured milliamp draw on system and it read .110, yes... .110. Also noticed there was a super faint (aaaaaaalmost unnoticeable to the untrained ear) ringing in the engine compartment.

Started pulling fuses and found it on the third fuse pull! WOW! Small fuse box in front of battery, 10 amp fuse supplying the ALT S circuit. Pulled it and draw dropped to 0. Did some digging and alternator cable sheathing was stripped by alternator wiring eyelet at alt. and entire power cable was grounded on engine bracket. Removed alternator and tested it at the parts store, D.O.A., and also noticed that somewhere down the line, someone had replaced the voltage regulator connector and simply twisted and taped the connections. Repaired both wiring issues properly (solder and heat shrink) and replaced alternator.

Retested milliamp draw. Down to .036 now. I had high hopes that the short was pulling so much voltage that it was causing the running issue. Not so much.

Vehicle still runs funny but alternator is charging 15 volts now.

HOWEVER, the faint ringing is still there (ignition off BTW). Got the stethoscope out and started poking around. Finally made it over to the alternator. It was emitting from it! It sounds like a mosquito flying in your ear. I pulled the 10 amp ALT S fuse again and it stops.


Pulled codes and JESUS HELP ME!


P1065 is ECM voltage issue apparently, so followed diagnostic flow chart in service manual from this forum. I have voltage supply to the ECM and code doesn't reappear after clearing.


P0223, P0122, and P0123 are all TPS codes. Apparently I don't have enough voltage to the TPS, and too much voltage going to the TPS all at the same time.


P0300 multiple cylinder misfire. I have replaced the plugs with factory plugs and Hitachi coils, which I understand were the factory choice. That is the extent of tracking this one down.


Also, I have successfully tested continuity on the cam sensor ground circuit and voltage supply to cam sensors. All normal. Sensors themselves ohm out according to service manual with no opens.


CURRENT QUESTIONS

1: Is a .036 milliamp draw on system normal?

2: Why does mosquito buzz disappear when the 10 amp ALT S fuse pulled?

3: Could the alternator power wire being grounded have fried the ECM?


Worth noting; Salvage motor from reputable source with 96k and 3yr warranty, new NGK plugs, Hitachi coils, crank sensor, water pump, alternator, battery and terminals, radiator and fan assembly,