Hey everyone, I'm new to owning a twin and new to the forums here. I recently acquired a 2017 BRZ PP and I am loving it. The only thing that hasn't been very lovely has been an idle dip that started occurring a couple of days after I got the car. I had been doing a lot of research on the issue and it seems like this was a common problem for some of the earlier BRZ/FRS cars. However, I would think after the TSB that was released, this problem would not occur on the 2017+ cars (please correct me if I'm wrong).
Once the problem had been around for a couple of days, I decided to replace the battery (which was the original 2017 factory battery) because the voltmeter showed under 12v at times even with the car running. Once I replaced the problem was gone instantly and the voltmeter held steady. The idle did not drop anymore and the car idled like it should. However, about a week/200 miles after doing the battery change, the problem has resurfaced. Even with the lights on and the voltmeter at 14v, the car's idle will still dip and cause the car to shake roughly.
However, strangely this is not the case all of the time. Sometimes the car will idle perfectly fine, then just start doing this at the next stoplight and continue for the rest of the drive, then for some reason, when I pull into my driveway and sit, it won't dip. Other times it will dip at idle from departure to return. Sometimes it won't do it at all.
I've got a video of the idle dipping (you can even see the dash lights dim at times when it dips) and a perfectly normal idle.
Also, just to be thorough, the car has a little over 17,600 miles on the odometer.
I was very excited when I replaced the battery and thought I had fixed the issue. Now I'm bummed out because my new baby is acting strange again
Any insight is much appreciated.