Ideas on t-shooting coil packs?

[Gearheadvr4]

I've got a random misfire code. Nothing specific to a cylinder. Ideas on how to narrow it down to which coil pack could be misfire?

I've swapped plugs with new iridium plugs, cleaned the throttle body, and purchased a new coil pack (not installed yet).

 

[Capote]

I had a bad coil pack a few months back, but I knew which one was bad because I got a code. What I did was swap the bad coil pack to the 1st cylinder and pull the wiring harness off of it, there was no change in engine noise. When I pulled the wiring wiring harness off of the good coil pack I put in the bad coil pack's place, the engine stuttered. That's how I tested it to verify that #4 was my bad coil pack. Maybe you could do something similar?
https://www.youtube.com/watch?v=JrYCrolDDkE&list=UUgSqSPctehpH-RhvqEfMx1g

 

[KNBlazer]

I've got a random misfire code. Nothing specific to a cylinder. Ideas on how to narrow it down to which coil pack could be misfire?

I've swapped plugs with new iridium plugs, cleaned the throttle body, and purchased a new coil pack (not installed yet).

Unplugging one connector at a time, then plugging it back in until you find the one where there's no change in idle...

 

[The_Roadie]

And P0300 codes often come from non-coil-triggered misfires, like low compression. Let's HOPE it's a coil, but there are more root causes possible.

 

[RayVoy]

And P0300 codes often come from non-coil-triggered misfires, like low compression.

Or, a vacuum leak

 

[Gearheadvr4]

I pulled each coil pack and all of them looked clean with no leaking oil except #3. Swapped out the coil on #3 and the engine smoothed out and check engine light went out after a short drive. So maybe found the issue?

What can I do to keep the oil leaking? Want to avoid this issue in the future. Maybe silicone around the gasket at the top?

 

[IllogicTC]

I pulled each coil pack and all of them looked clean with no leaking oil except #3. Swapped out the coil on #3 and the engine smoothed out and check engine light went out after a short drive. So maybe found the issue?

What can I do to keep the oil leaking? Want to avoid this issue in the future. Maybe silicone around the gasket at the top?

It's better to replace the gasket itself.

 

[Gearheadvr4]

I was afraid that was the answer. Any guides out there on how to replace the gasket. Seems pretty involved.

 

[Royalwapiti]

9 times out of 10 the #3 coil and plug go bad due to the water coming off the windshield and settling on top of the engine area. Some of the water always finds its way into #3 plug and coil. There's a TSB out there that describes this problem and a dealer fix. Why #3 and not #4 or #2 I dunno...but that plug will always be the most corroded.

Don't worry about changing any gaskets.

Use some electrical silicone goop in the coil and boot and put her back together. It usually gives a P0303 misfire, specific to the cylinder but apparently not all the time.