Wavering Idle and Dropping Voltage

earwicker7

Unsrew the cover (there are three for each terminal). Get a tiny flashlight and point it towards the water. There are some straight lines below the surface of the water. There are two metal "prongs" (for lack of a better word) which should be touching the water; if there is enough water, the lines will "bend" in the area around them. If the lines look straight, you need to add DISTILLED water; I use a medicine dropper.

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2009 Magnetic Black 370Z with Touring, Sports and Navigation Packages--Fast Intentions CBE with 12" Resonators/Carbon Fiber Mufflers and LTH--Stillen G3 Cold Air Intakes, Underdrive Pulley and Grounding Kit--Uprev Tune

spearfish25

Just make sure you top the battery up with Nissan Ester Water.

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2013 Cadillac V-Wagon, RIP Z

SoCal 370Z

Rep pint & point for that pup!

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dad

Did you try what I posted, post #2?

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v8zracer260z

It is normal to see some fluctuation in the voltmeter depending on the condition of he battery and the loads on the system. Typically 13.0 to 14.5 is a normal range. Though low voltage indicates a non charging symptom ie alternator or regulator problem and over charging sytem can cause more problems. Over charging of more than 15-16 volts can blow out lights and fry computors leading to expensive repairs. In addition to checking the level of the fluid I would recommend checking the specific gravity of the battery acid with a hydrometer found at any local auto parts store. This is a better indicator of battery health. Water has a specific Gravity (SG) of 1.000 in a Sulfuric Acid battery A SG of 1.265 is ideal and it can be slightly higher or lower in each cell but if you have one or more cells showing close to 1.000 indicates a dead or shorted cell it's time to replace the battery. Also since you have a wavering idle that in itself may be causing your voltage to drop. Your alternator puts out very little charge if any at idle. Dropping below that rpm may cause a significant drop in charging voltage. You may not have anything wrong with the charging, but have an idle conrol issue. Just a little advice from a prior F/A 18 Avionics Tech Hope this helps you guys out.

earwicker7

Yeah, nothing like that. I think I was over-reacting to normal behavior that I had just never noticed.

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2009 Magnetic Black 370Z with Touring, Sports and Navigation Packages--Fast Intentions CBE with 12" Resonators/Carbon Fiber Mufflers and LTH--Stillen G3 Cold Air Intakes, Underdrive Pulley and Grounding Kit--Uprev Tune

earwicker7

Thanks! I used to have a hydrometer for my saltwater aquarium... wish I'd kept it.

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2009 Magnetic Black 370Z with Touring, Sports and Navigation Packages--Fast Intentions CBE with 12" Resonators/Carbon Fiber Mufflers and LTH--Stillen G3 Cold Air Intakes, Underdrive Pulley and Grounding Kit--Uprev Tune

aalqaedi

Guys,
Try this. Go to your MFA sensor. Turn your car off, unplug the MFA sensor. you will get check engine. plug the MFA sensor agine, and use any OBDII and erase the fault code. It will be fixed. I just figured it by luck.
One more thing, when your idle goes to 13's use the wiper, does the idle goes agine to 14's. mine does, that how i figured it.
good luck.

KingZee

I started having a weird issue today and wondering if it's the same as this issue...I was city driving all day in Hollywood and it's just crazy stop and go traffic. Normal ~190 oil temp. I have an '09 manual. When I come to a complete stop or car was in neutral, 7 times out of 10 I would say, idle would drop, car would shake a bit, then idle would go back to normal, after a few times of this happening I started to notice that every time it would happen the Voltage would drop and I'd always catch it on its way back to 14 as idle goes back to normal.

I was guessing voltage drop is due to car almost shutting off because of low idle/shake then when idle goes back to normal so does voltage but I don't know why the idle is acting weird? Could this have anything to do with my "recent" exhaust install/tune (or lack thereof)? Or is this pretty much exact same issue OP was experiencing and I should just check my battery and not worry about it?

Thanks as always for any input guys

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Focus ST

16valve

I had this same problem and in my case a new battery was the fix. After 52,000 miles and 3.5 years the crappy stock battery was done. The car would seem like it was going to stall out when stopping at an intersection. I read this thread and discovered about the maintenance Required battery. After adding 1 1/2 cups of distilled water to get my battery back to level, the idling problem was much better, but I could still see the volts fluctuating. I had the battery tested and it was done. I have a new Optima battery now and all is good.

KingZee

Good to know, thanks

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Focus ST

Javier

I've had my 'Z' for 11 years, I'm a avionics technician in the aviation business for 37 years. For those who do not know what a avionics technician is, I work on all of the electrical and navigation system of an aircraft. Battery voltage on my 2009 "Z" never fluctuated "NOT EVEN A TWICH", in 11 years. it stayed at 14.4 volts no matter what you turned on in the car. My problem started when my battery crapped out on march 2020, a week later the alternator went out and like I have never done before went to an auto parts store and replaced with one of there's. The battery voltage and idle drop started soon after. Returned the alternator to the auto parts store got another one, no joy. Returned the battery and got another one again no joy and problem persists. Purchased a brand new alternator from Nissan $650 dollars later no joy. Replaced battery with brand new high output gel battery $450 dollars later and still no joy. so for those that think its a battery, alternator, and yes by the way I did purchase two new MAS sensor from Nissan and still nothing. Its none of the above. The battery voltage drop should be so slight when operating normal that you will never even notice it ever. There aren't enough system draw in a car to overcome a 120 amp alternator. I have contacted Nissan and they are mute about this issue. If someone comes up with a fix please advise.

markesc

Same issue on my 2014... but it really cost me.

So it started doing the idle drop thing, but I thought that was because the transmission had been replaced and I honestly just decided since going through that whole process I'm not going back to a nissan dealer unless its an issue that prevents me from driving.

So one day on the way home from work, got food, got back in the car, and had this horrendous smell. Turns out my RF amp and sub both self destructed. I'd noticed lower voltage than normal on and off over the preceding few weeks, but it would go back to above 14v most of the time.

After the amp/sub both self destructed, and letting the car sit and air out from the fumes produced, the car wouldn't even start. It only sat for two days.

Got the 6 year old battery replaced and all has been perfect since then.

Moral: If you have an older battery and run a few subs, even professionally installed, there's an added risk. Better to get the battery replaced ahead of time or tested as soon as any symptoms show up... As much as RF says if in an under current or voltage scenario the amp will self protect, that's wonderful except in cases where it doesn't do it fast enough and destroys the sub.

So I was out:

a new battery
new amp <--- luckily I Have a new RF amp, a much bigger one sitting on standby
new sub <---- will likely just have a custom box done for the spare tire area since there are a lot of thugs/wanna be thugs in phoenix.


So: Don't be like me!! get the battery checked and replaced ahead of time, so this way you save yourself from other possible related issues. Mine had zero issues starting up each day, the only real symptom was as others have mentioned, the rolling into a complete stop and subsequent RPM drop.

This is the FIRST time in 30 years of aftermarket car stereo use I've ever had an amp or sub go bad on me, and had both installed professionally, and both are reputable brands: RF amp, JL 10w3 sub. Clipping is a killer, and so is my boneheaded move to not just get the battery replaced sooner as preventative maint.

markesc

Wow... now that's a nightmare!!

Any updates?

I'm now looking at toyota/lexus products...

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.