996 Turbo CEL P0492 + Misfire Cyl 3 & 6

[mhariush]

Just picked up an 03 Turbo with Aero Kit and X50 package and when I started it up today it threw these codes. I have had it about a week and half and driven it a bit and this is the first issue.

Car has 146k miles (highway miles as it was a commuter car for the 2nd owner) and it has had a good amount of work done 3-4 years ago (a few thousand miles ago)

The codes are:
P0492
P0300 Misfire detection (total)
P0306 Misfire, Cylinder 6
P0303 Misfire Cylinder 3

According to the records, the car had plugs and coils (997) replaced less than 3k miles ago. But does not look like it had the spark plug wires replaced...

It seems a lot of people have had success changing plugs/coils/wires, and I guess I should start by trying the wires?

What is the P0492, that seems like a generic one but it says refer to service manual (using the foxwell reader).

The car seemed to run just fine, but every now and then there was a sound, coming from the right side (passenger side) that almost sounded like a motorcycle or car revving. I thought it was someone else a few times, but then I heard it when there was no one else around.

[mhariush]

So, little update on this. I was working on adjusting the driver side window yesterday because there was a gap by the mirror creating some annoying wind noise. I was not able to adjust the window correctly, I ended up making it worse, so I have to go back to it later. But while I was doing this, I managed to drain the battery and basically kill it. The car didn't want to start, threw a Failure alert with a red lighting bolt on the dash (forgot the actual phrasing). I tried to charge the battery over night but it only reached 25%. The battery is fairly new, 12/22 it says on it but it sounded like the car had been sitting for most of time the last few yers so I think it was on it's last legs and then I killed it.

I managed to start it with that 25% and the car did not like that! It started and ran, but really rough and then it died. So I went to AutoZone around the corner and picked up a new AGM battery, started the car up and it ran perfectly. Took it on a 100+ mile drive with mostly highway and some start and stop traffic and several stops with parking and starting and not a single issue. No CEL, no stuttering, no hesitation. It ran perfectly.

So it seems like it was just suffering from a dying battery.

[OldSharp997]

Be sure to check your charging system since the battery was relatively new to have died.