*Sorry for the large pics. Not sure how to resize them*



Like the title says, for the past few months my G has had some very irregular volts. I first noticed it when I would come to a stop light. About a second after coming to a complete stop the car would sound like it was trying to stall. I noticed the RPM's dropping as well, maybe to 350. The car has not stalled as of yet. I took her into the dealer after Autozone tested and said the alternator was bad. The dealer performed a test




and said the alternator is good. They replaced the battery. Basically I was told there is nothing wrong with the car.


I can coast in neutral for a mile or 50 feet, but when I come to a stop about a second later my RPM's drop and the car almost stalls. I borrowed a buddies volt tester that plugs into a cig/12volt.




I then thought, what if this voltmeter is off. Here is my radar detector hardwired to the 12volt. (to be fair the meter and radar are measuring the same source, but I can move the voltmeter to the true 12 volt in the arm rest and still have the same volts)




And finally I remember the torque app can measure volts.



I can roll the windows up and the same does struggle a bit. My buddy said it could be fuel, but I have gassed at many different stations and usually use Shell, will sometimes us QT or Racetrac. Always use premium. I have tested the volt meter on my mother's evoque, my buddy's M5 and an Infiniti SUV from the dealer's loan car department, all with a steady voltage.




Synopsis: Car has low and highly fluctuating voltage. Car almost stalls when coming to stop. Help me figure out what it could be. Dealer is aware of the continued issue and is of no help, even though I have extended warranty.

 

Your battery could be on its way out and or your alternator. I'd start with a new battery since its probably cheaper than an alternator and easier to put in yourself. IF the symptoms persist have the alternator checked out. After that...start scrating your head. LoL. Good luck

 

Alternator.

 

There's absolutely no way, whatsoever, that it has anything to do with your fuel. So lets just get that out of the way.

Battery itself, or the alternator. My guess is the alternator, you should be getting around 14v when the car is running.

 

Well the dealership is reluctant to replace the alternator. "Infiniti never has bad alternators." and "I have never seen an alternator replaced since I started working here." *rolls eyes* You'd think with my AFTERMARKET WARRANTY, they would love to throw parts at the car.


Thanks for the input guys! Gives me some more ammo to fight the dealership with.

 

The dealership I took my car to swore that they'd never encountered a leaking rear timing gasket either and that mine must be an anomaly. Riiiiiiight...

Internal combustion requires fuel, air, and spark. It's not fuel or air related, it must be spark. Battery, alternator, and grounding are the components. You've swapped the battery. When voltage is low (14.1v) with the car running normally the alternator is often the culprit in my experience.

 

Just stand your ground and tell them you want a new alternator. I hate dealerships for this reason, they think they know best all the time. So what if they never have had to change on e before...you need YOURS changed. Its not like they are not getting paid for it. Be stern with them. My wife's starter was going on her Accord and they tried to ignore it and say it wasn't the starter. She threatened them...she said the car is still under warranty and I am telling you what the issue is. If it dies on me once its out of warranty we are going to have a problem. You will fix it either way and I am not paying for it. Needless to say we got a new starter. Just stand firm and tell them all signs point to a bad alternator and demand it get fixed. Good luck!

 

So these are the volts upon start up. Still think it's the alternator?

 

So you've got 14 volts at start up and then it drops to 12-13 as you continue to drive? That's an alternator.

 

Correct sir. I figured it was, I'll keep yall posted on what the outcome is

 

With voltage at the alternator at 13 or higher it may be getting weak but im not sure its bad. The car doesn't run off the alternator, its runs off the battery and the alternator charges the battery. As long as youre getting more than 12 volts into the battery then its doing its job of charging.

This sounds a lot more like a dirty MAF or other sensor. What exactly was it that put you onto the voltage trail of diagnosis? A dirty MAF is going to report incorrect air and cause a lean or rich state which could cause exactly what youre seeing with low idle rpms. Being stopped vs coasting is going to give less air and warmer temps when you stop causing the issue only at stopped idle vs coasting with cool higher pressure air.

Also the cars systems are always going to be around 12v. From the pics im not seeing wild fluctuations of any of the voltages and i would expect a margin of error of +-1v. The 14v you see at startup could just be a healthy system allowing higher voltage for the starter. Those things are major electricity hogs and need a ton of juice to run.

 

MAF is a part of the fuel system, not the electrical system. A MAF issue won't affect voltage.

You're right about the alternator charging the battery. That's why a running car typically runs at about 14v, if the alternator is performing properly it needs that voltage to charge the battery. A measurement of 12v while running is low. That should be battery voltage when off.

 

I hate to ask the obvious, but have you installed anything electrical recently? Aftermarket amp, hard wire charger, lights...?

 

Only thing electronic installed is my escort. Turning it off does not change the volts and leaving it off does not change the volts. And that's been installed for a while. I spiced I to the positive and negative 12v. And the positive from the escort is connected the positive of the 12v, and vise versa.

Turning my headlights on does drop the volts,

 

On the way home there is a very long 1/4 clover entrance ramp. Able to drive the car hard around the corner and keeping the rpms well above 4,500 for probably lyrics 30 seconds. After I came out of the turn I topped off the current gear. I checked the volts on my escort and I was at 13.9. I checked the the volts again a few seconds later and it was back down. To 13.1ish.

So it seems driving the car hard for a long period of time, the volts rise. Still think it is the alternator?