I have a 2005 Legacy 2.5i non-turbo. Starting yesterday the engine started hesitating a tiny bit on acceleration while my wife had the car. That evening she noticed the engine light went on and the cruise control light started flashing.

I went to a parts store today and they pulled a code - P0303. Misfire in cylinder 3. After hearing the cars issues, the parts person said most likely plugs, plug wires, or ignition coil issues.

The code is off now, but the car continues to hesitate when under load - more noticeable when accelerating in 1st gear. Idle is fine. Starting seems ok too.

I bought the car 6 months ago from a family member. It has 150,000 km. The head was redone (with new plugs) around 90,000 km - so 60,000 km ago. Not sure if plug wires were replaced but they look to be in ok condition.

I removed the #3 plug today. I've attached a few photos if someone could give their opinion. 

I'm thinking to buy new NGK OEM platinum plugs at around $9.99 CDN each. If that doesn't solve the issue perhaps I should replace the plug wires? 

A diagnostic seems to cost a few hundred bucks, so I thought why not replace the plugs before going that route?

Thanks for any / all advice!
 

Ah and here's one more photo .. rough gap measurement (didn't force anything in)

 

 

Plugs are cheap. Change it.

Sorry but our gap is measured in mathematical units, not blade bits. lol.

.044.

Move the wire from three to one.

If the code comes back on one, you know it's the wire.

Very seldom a coil with only one cylinder.

Pull the wire off the coil and see if either connection looks burnt or corroded.

Thanks guys. Spark plugs ordered. Wires next on list (will try ocei77 trick to test them, if needed). 

 

PS - how many blade bits is the gap supposed to be? Haha

try spraying a little water around the wires with the engine running esp. at night and see if there are any sparkly lights

had the same issue a few months ago on my 08 when it was exceptionally damp in my cold garage

ran rough and code issued

 it hasn't recurred.

2 hours ago, xocomil21 said:

PS - how many blade bits is the gap supposed to be? Haha

do you want metric or standard value?

2 hours ago, xocomil21 said:

PS - how many blade bits is the gap supposed to be? Haha

I don't remember having to change the gap on NGK plugs for our 95 and 97 RHD 2.2s.

So, you probably won't have to use the blade bits.