Last spring the daughter’s 2k Max (164k miles) started not holding an idle and the hated code P0505. Pulled the TB/IACV off and checked the resistance, found 2 contacts 0. Replaced with a used Infinity assembly (32k miles) and all was fine. Monday, 8k miles later, the SEL came on and no idle. I hooked up the reader, P0505. Tuesday I started the car to take it to the back garage where I do all my work, and it immediately stalled and had to hold the throttle. Once in the garage, I disconnected the battery and removed the TB/IACV and checked all the values, and to my surprise, no problems. I then checked all the incoming voltage and all was fine. Scratched my head, then put everything back together, started the car and it held the cold high Idle. Took it for a ½ hour ride and it was fine. She has driven the car each day since and no problems.

Any 5G guru’s have any insight into this phenomenon?
Only explanation I could offer was that the battery was disconnect for a couple of hours, but have no experience with that theory.

 

a bad IACV 99.99% of the time fries the ECU (thanks to the wonderful Nissan Engineering). I don't know if its true the other way around (bad ECU shorting out a good IACV motor)
Get a used ECU from a junkyard. Make sure the numbers match. You would need to get the idle and the keys reprogrammed as well.
From the tests you conducted, it looks like your infinity IACV motor is still good.
At least thats what i and most owners went through.

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if the problem didn't reoccur then your ecu most likely didn't burn. Disconnecting the battery resets the ECU and the idle. I would still however recommend getting the idle relearn procedure done regardless..



Good LUCK!

 

Thanks for the reply. Never did have the idle relearn done, but the daughter just called from North Jersey about an hour or so away, and the car is still running great with with no problems. I erased the SEL code after reading the problem and it still hasn't come back on.
She won't be back until next week, so I'll wait and go from there.