2008 tacoma 2.7 rough idle/alternator related

Not new to the tacoma, just haven't had one in a while.

I picked up a 1 owner 2008 access cab 2.7 5 speed 4x4 with 138k and absolutely love the truck.

Not knowing much of the history i decided to make sure all maintenance was up to my standards.

Truck had a idle fluctuation operating temperature. Noticeable when coming to a stop.

I have a extensive background in vw repair and am pretty efficient at diagnosing electrical gremlins.

Being a new to me truck, i did a full tune up. (ngk plugs, coil boots, pcv valve, throttle body/maf cleaning, air filter, oil change, vacuum lines)

Running diagnostics with my scan tool showed 0 misfires across all 4 cylinders. But truck had autolite plugs and wanted a fresh start,


Battery is a newer interstate megatron and someone along the way swapped the alternator with a duralast from autozone. Voltage while running is 13.62

The truck when having a rough idle bounces between 600-800 rpm. If i unplug the voltage regulator on the alternator while it is doing this the idle smooths out instantly. (vw's have this issue when the one way bearing locks up on the pulley)

So is this a voltage regulator issue (magnetizing the alternator to quickly), or a pulley issue? wanting to see is anyone has changed one part or if my best bet is to just order a denso unit.

TIA

 

Ordered a denso alternator today. Will update once installed in case anyone else has this issue.

 

I'm trying to follow you here. If the voltage regulator is in the alternator, how do you unplug it and nothing else?

I believe autozone alternators have lifetime warranty; if you get the receipt from the original owner, you can get a new alternator from autozone.

 

The alternator has a plug and a charging stud. I am pulling the plug, which is having the vehicle run on the power of the battery. The plug on the alternator is the voltage regulator. The stud is the rectifier.

truck was purchased from a dealership so I don’t honestly know who the original owner was.