I have an aftermarket volt meter installed inside the cabin. It is wired directly to the primary ignition wire @ the ignition switch.
Every morning I would start the car and my meter would read 14.4v. As the vehicle warmed up the voltage would drop to 13.8v and pretty much stay there.

After replacing the alternator today I noticed my volt meter reading 13.7v at startup and after it warmed up it drops to 13.4v then goes a little bit up, then a little back down, then back up to 13.7v then back down etc etc..

I figured something was up with this alternator so I had it replaced.
Slapped alternator #2 on today and I'm getting the same readings..

Bc my voltage is bouncing around below 13.7v the vehicle is running not so smooth. Feel's like there's a massive current draw causing the voltage drop causing the vehicle to idle not so well..

The alternator and battery sit between 13.8v and 14.1v
With the vehicle off battery reads 12.5ish

I'd also like to mention that the cars been doing more sitting than driving past few weeks bc I had dropped the lower and upper oil pans along with the front and rear valve covers..
The intake manifold was removed to get to the valve covers. I also cleaned the IACV and EGR tube and EGR tube sensor.
Throttle body was removed to get to all the tiny vacuum lines.
Everything got a new gasket was re-installed like I found it
I also accidently removed the throttle position sensor. But the vehicle seems to idle at about 700 fully warmed up.

Somethings just not right here.

Any help much appreciated..

 

Have you checked and cleaned your grounds? AutoZone can also test your battery for the free

 

Going to go through all my grounds in the morning. Battery was purchased in July.

I have checked the voltage at the cigarette plug and its reading 13.8v but the ignition wire drops to 13.4v

 

Even if it's a new battery sometimes they have dead cells, if you had the intake manifold apart maybe it's got something to do with the grounds for the fuel rail but the body/engine grounds are usually pretty corroded at this point

 

If the battery had a dead cell, it wouldn't read 12.5 volts. It would read 10. something.

 

My car ran perfectly fine prior to the Upper oil pan, front & rear valve cover, cleaning of the IACV & EGR Tube.

I just don't understand what I'm missing here.

As of right now,

I'm getting 13.5v at the ignition switch after start up. Once I put in gear rpm drops to 500ish and volts drop to 13.2.
And the exhaust smell is super strong giving me a headache.
Plus there's excessive water build up in the muffler

 

With a new alternator from Nissan, i get 13.8-14.0v when first starting the car. It goes down to 13.4v after warmed up sometimes. This reading is through the cig lighter. When i had the Bosch unit, it would be in the mid 14s at first start and go down to the upper 13s sometimes after being driven for awhile.

 

My cigarette plug reads 13.8v
Ignition drops to 13.2v. Thats when the car starts running like crap.

 

Turn on everything while it's at idle....Everything is:
Headlights
foglights
rear defroster
a/c fan at full
caution lights
brake lights
Now see where you are hopefully over 12.8v

 

I am not sure that many or even any cars will be able to keep up with that much load at idle. i would expect to see some drain from the battery. But as i say, I am not sure.

 

His IACV, if both Throttle Position and CPS is connected, should compensate for the load on the engine and electrical system

 

I can't speak for other brands of cars, but the Maxima should and will. I would be worried if the voltage dropped below 13 volts. But if the voltage dropped to 12.8 like CMax03 said, you would still be in good shape.

 

Reason I'm concerned is bc I'm big into car audio. I'm constantly watching my voltage. Especially @ the ignition.
It's never dropped below 13.8v on me with all accessories off. Now I'm at 13.2 with all accessories off and in gear.
At cold start up everything is well. Voltage is above 13.8v. Once it warms up the voltage drops. Idle drops. Car feels like crap.
You can hear/feel stress on the motor and in the exhaust while its in park.. And the exhaust smells too rich..

So far I've traced all 97% of the wires to the ecu.. No broken wires or plugs.
Removed the entire EGR system and cleaned. Tested the egr valve, bpt valve and solenoid. All hoses replaced too
Tested IACV for movement switching key on/off.


Tonite I'll be testing the MAF and TPS.

 

If the idle is dropping when the engine warms up, Then this is the problem. The engine should idle at approx 650 to 700 rpm. The alternator has a certain minimum rpm, so if the idle is below spec, the alternator output will also be low.

Have you tried cleaning the throttle body and throttle plate?

 

pWell that's a load test whether you know it or not that will determine the state of your electrical systems output...Again anything over 12.8 volts you're in good shape! So I guess you don't run your a/c, radio, lights, nor use your brakes ever at the same time? Buy yourself a battery analyzer or a OB2 tester that has a the electrical system test feature....

 

Guys, is it possible my ecu needs to relearn everything since it's been unplugged for more than two weeks? And this is why I am having excessive power draw, idle problems and seems as though the vehicle is running too rich?

Could this all be bc the ecu has been cleared?

I'm starting to think this may be the case.

 

I could see how the ECU would need to relearn, but don't think it would be related to electrical draw since alternator is what supplies the voltage and ECU has no control over that. Are you sure it isn't an issue with an old battery or one that may have been discharged fully one too many times?

Heck, as long as your voltage isn't dipping into the low 12's, why not just drive the car and not worry?

 

Self induced problems....Your ECU won't have to relearn a thing..The motherboard/memory is there to stay....Maybe your voltmeter or it's wiring is thecause of that minute variation in your voltage reading...It's not a real problem Bro!

 

Did you every find your solution? I just did the alternator after i started to see my alternator slowly dip in voltage as it warmed up but it didnt fix my issue and my old alternator tested fine at AutoZone. It really started after i cleaned up my iacv and throttle body but i still am going crazy trying to find the solution. Even the fsm says there is an issue if there is an electrical load at 2000rpm and the alt reads less than 14.1v i believe. Please help before i go through the whole job again.