Still low voltage help

Soo new battery and alternator
2006 tacoma
2.7


Driving voltage 14.8 come to a stop it will drop to 13.0. What causes this and how I fis it. Is it cause low rpm? The only code is the speed sensor #2 works intermittently

 

13v isn't bad at idle, you have to remember the alternator is turning slower at idle so output will be lower.

If idle speed is a bit low you can clean the throttle body which may help improve it.

 

Loose or worn belt. Bad connection between the battery terminals and posts.

 

Yes but feel like it gonna die out. What about the maf

 

Noo. Belt has 90k on it bad connection? I just cleaned and changed out

 

I think you are fine.
Toyota doesn't want you to check the charging system at idle.
They spec it at 2,000 RPM

 

Cleaning the throttle body will likely fix the low idle, you can clean the MAF sensor if it's dirty but be very careful with it.

 

Well seem like it wasn't this bad before when I stop everytime feel rough idle and the truck wants to die out

 

At idle, does rapidly increasing electrical load have any discernable affect on things? My guess would be that the rough/low idle is causing you to have a slightly lower voltage and not the other way around. I'm no expert, but 13V should be just fine, and it's higher than what your battery would produce on its own, so it should be completely sufficient to drive any electrical system on your truck. If the amperage is insufficient, that could be another story... that's why I'm curious if adding/removing electrical load changes things at all.

 

That doesn't sound like a charging system issue.
Clean the MAF and TB as suggested above. See if that helps.

 

Will try today and let you know can you use throttle body cleaner on maf or gotta use separate cleaner

 

My 2010 had always idled around 13.0 at roughly 700 rpm. I can get it to drop to around 12.5 if I'm really blasting the stereo though; that said, mine isn't idling rough as you're mentioning.

 

Is that normal, even with headlight on and off.

 

In my almost 12 yrs of having the truck, yup. I got it 3 yrs old with under 7k miles.

FWIW mine is also a 4 cylinder regular cab, power nothing.

 

Cleaned both and drove for 5 min only look and sound good will see the ultimate test when I drive to work tomorrow. Voltage stayed when I stopped a couple time.

 

Ok did and look like fix problem no.voltage drop when i.step and hold.the.brake. when I come to a light no rough idle. Thank God fixed the problem.