My wife has a 2001 Legacy L with 120K miles. For the last couple weeks when she has gone to accelerate the car has hesitated a bit. I was driving it earlier this week and I went to floor it to merge onto the highway and got a loud noise and a big hesitation. The car then drove normally. My wife said a couple days later the check engine light went on and off a few times. We took it to autozone and they said it had a cyl 2 misfire. I did the plugs at around 90K but didn't do the wires. At 102K we had the head gasket, and timing belt done. What is likely the cause of the misfire? From doing a search here it seems that plug wires might be the cause.

You need new ignition wires (spark plug wires). Use Subaru only, the only suitable substitute for aftermarket wires is Magnecor. After hearing a loud noise it might even be worth checking to make sure the wire didn't just detach itself or looking at hte engine and make sure nothing is flopping around or obviously wrong. But i'm guessing the loud noise was a backfire?

 

As a side note, this is only for Subaru EJ engines, not a "general" rule of thumb. The EJ motor (like the EJ25 you have in the 2001 Legacy) are not forgiving when it comes to ignition components, it is best to use OEM Subaru plugs and wires. The plugs, NGK, are available far cheaper at any auto parts stores than at Subaru.

 

Now there is a chance it is something else, but yo'ure at the mileage that the wires need to be addressed.

What brand/type plugs do you have in?

What brand/type plugs do you have in?

 

I thought I had used the NGK plugs but I did not. That was before my days on this site so I was uniformed. I had used Bosch Platinums. When I went to change them they were in pretty bad shape. It looked like there was a little rust around the base of the ceramic portion of the plug.

Since the change of the plugs and wires we have had 2 day of normal operation. The check engine light has also gone off.

When is the last time your front 02 sensor was replaced?