Wavering Idle and Dropping Voltage

KingZee

Good to know, thanks

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Javier

https://www.youtube.com/watch?v=vYtyDX9RTWs

My 2009 370Z after the alternator crapped out, I have replaced it twice and battery twice. The problem persisted, after doing some research it turns out that the PCM (Power Control Module) gets confused about where the throttle valve positioning should be. Also the PCM controls the alternator and tell it when to and not to charge the battery. Most of the computers on the Z have capacitors, they store energy to keep the processors energized with small amounts of energy so they do not loose their memory. I searched YOUTUBE and found this video on how to give your Z and many other cars an enema. Accomplishing this video to the letter fixed my Z. The link above takes you directly the the video. Once you accomplish this and restart your car all the computers reset themselves and you will see the voltage drop and come back up at least once if not twice while the car re-calibrates itself. If by chance the link does not work the title to the video is : How To Reboot Your Car ~ Battery VooDoo.

SouthArk370Z

Or you could take one of the battery terminals loose and step on the brake pedal for a few seconds. Will work with any car that has functioning stop lights when the car is turned off (ie, all of them).

There IS a good reason to take the negative terminal off first - if your wrench shorts to ground, you won't have a dead short. Once the neg is loose, shorting the positive to ground won't hurt.

Putting a dead short (the jumper in the video) across charged capacitors is a bad idea. The rapid discharge can damage capacitors and other elements inside the ECM. Most are rugged enough to handle it but why take the chance? If you use the jumper-wire method, put a resistor in series.

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POS VETT

Can you scan for the DTC?

markesc

That's the plan, still looking at scanners on amazon at this point...

** ordered charging system tester and 3-in-1 tester/code reader/multi-meter; Figure whynot have both and have some redundancy. **

markesc

Well... not really sure what to say now...aka: dog chasing tail!

P0603 So this must be just from leaving the battery disconnected a few days which is what I've been doing out of fear that I have some parasitic draw or god knows what at this point.

As stated above, it wouldn't start after 3 days of sitting with avg temps in the 110-120 degree range outside (car is garaged).

Tester says the charging system: battery, starter draw, alternator are fine...

Here's my plan: Leave battery connected, test it each day, and go from there.

JSON

Bumping this back up. I've noticed my car didn't start after a week of no activity. The battery was about 9 months old, but I went to the shop and they recharged it. It then started up fine. It's been fine for a few weeks but just noticed that my voltage fluctuates from 12V to the normal 14.5V or whatever. I've never seen it dip that low. I noticed even while driving, it goes from 12 to 14, then stays at the normal 14.

Is my alternator going? Not charging the battery consistently? That doesn't seem quite correct either.... Thoughts?

Brxce

I’ve been having the same problem but maybe worse a couple days after doing pads and rotors. I can’t see how doing pads and rotors would cause this issue except if I may have installed the pads wrong and the wear sensor is in the wrong orientation? Anyways, my volts are dropping down to the 10s at points and most noticeably when it’s acting funny, when I go into 1st gear, the volts drop just below the line of 10v and the car sometimes sounds like it’s gonna die. Starting the think maybe voltage regulator, which IIRC is inside the alternator? Any help would be great