Wavering Idle and Dropping Voltage

Javier

The issue is permanently fixed and voltage steady as a rock at 14.5 like it was for the last 10 years. I did place a response and if you cannot find it follow this video to the letter.

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

Like I stated on my response the battery voltage my swing back onc or twice while the car re-calibrates itself.

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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Rusty

Nice job on finding that.

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Javier

As I had previously posted, I thought my problems where over when I discharged all the car capacitors. Wrong it cam back shortly after that, again the idle and the battery voltage fluctuating at idle. I found the true fix for this and you probably are going to think I'm nuts but here we go. When I replaced my original alternator that fried itself I followed the installation procedures in the manual under CHG (charging) in that section it tell you to go to EM (engine mechanical) to check tension. This is by checking the tensioner and making sure that it is between the lines as shown in EM-13. Here is where the fun begins, I found that my belt was at the last line which indicated it should be replaced. I had just replaced the belt 40k ago, then in EM-13 it says tension adjustment refer to : EM-139 DRIVE BELT. Wonderful, I go to that page and it states no adjustment needed self tensioning. I started my t/shooting again. I removed the serpentine belt. I found that the alternator stay item 6 on CHG-24 has the hole that attaches to the engine side elongated. It's not plug and play, I wedge a piece of wood between the alternator and the engine to force the alternator as far out as it could go. Then I torqued all the bolts, installed the serpentine belt and behold the tension was perfect in between the limits indicated by "B" on EM-13. I started the car and behold all perfect just like before my battery and alternator crapped out. No where does it tell you about the alternator stay adjustment. Now I do not know if a bushing or sleeve may have fallen out of my stay but from the pictures I have seen there are none. At idle the belt is hardly touching the pulley even with the tensioner in place. Its been a two weeks since I did this and all ok. So I loosened up the alternator stay and retorqued it without taking up the slack and the car started acting up again. So at least in my case I have confirmed the cause of my problems.3 batteries 3 alternators, 2 mass air flow sensors and numerous hours later it is fixed. Hope this helps some of you.

[IMG][/IMG]


http://www.the370z.com/members/javie...nator-stay.jpg

http://www.the370z.com/members/javie...-tensioner.jpg

markesc

Hello everyone!

Could GREATLY use help on this.

So as my above post mentions, I had the stock battery last for around 6 years / 60k miles. One day all of a sudden my bass amp (RF) just self destructed, and so did one of my JL Audio 10w3's. So bad, that the entire interior smelled like an electrical melt down! Pulled Sub box, and stopped using amp.

A month later, the stock battery would not start the car without a jump start. Took to dealership, had battery replaced. Everything was FINE.

Until about 2.5 weeks ago I stopped driving the car every day, and would let it sit in the garage for 2-3 days. Then one day it wouldn't start without a jump start. Then 2 days later, car starts on it's own just fine. Then a day after that, completely DEAD. Not a single light on the dash, nothing works at all. My tiny taclife jumpstart battery failed to work even after charging it to the max.

So called the insurance company, tow truck dude shows up with a giant jump start battery type (the blue one with the handle). Car turns over slowly and finally started after about 3-4 seconds.

Drive car straight to dealer - dealers tests battery and shows me a receipt tape like print out stating the battery they put in there 4 months ago is just fine.

Since then, I've been just disconnecting the negative terminal if I need to let the car sit for more than a few hours as I'm now working from home like everyone else.

One thing I've noticed, which is similar to others posts: the voltage meter.

Recently at stop lights, I notice the voltage drop to one tick below 14, and then if I'm driving for quite a while at 80+mph on the freeway, then it will slowly go back above to 14.1-3ish. In the past 6+ years of ownership, that battery voltage thing barely moved, and now it's moving around consistently, especially at stop lights. I've also had that strange idle rise/fall only once at a single stop light.

Other facts: 72,000 miles on the car now, serpentine belt has never been changed, stock alternator, battery replaced 4 months ago, and I did relocate to phoenix (hot as an oven) in January - The heat here kills just about everything, and I'm told by many that it's not uncommon to only get 18-24 months out of a typical battery. I did finally completely remove the dead RF amp that may have been doing some type of parasitic draw, but it does not seemed to have changed any behavior of the volt meter. Other than that, I'm running a 5 year old pioneer deck going to a 4 channel RF amp that was installed at a stereo shop. I did check to see if the amp that is working shuts off, and it does.

I'm open to suggestions on where to look next, and I may simply have to start with cheapest stuff first: serpentine belt ? (mine is about dead center per the diagram below)

Please advise if anyone has any ideas.

markesc

Well finally got a SES or " Service Engine Soon " light... will have to buy code reader and go from there.

Was hoping some people could chime in with ideas before the stealership tries to BK me! Will post again with update

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