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.

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.

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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

earwicker7

So, I took it in again and the head mechanic said it's nothing to worry about, that it was probably always happening and I just never noticed it. He said that the battery is 12V, and the alternator adds the voltage on top of that. He said it is normal for the voltage to fluctuate between 13-14V when the car needs a little more electrical power. He said that the engine idles a little higher now and then to give the alternator some extra juice.

He did say that it is a problem if it goes lower than 13V; usually, mine only drops to about 13.5V.

Any comments on his verdict?

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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

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

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

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

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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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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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.

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.