Hi All,

I've read quite a few threads from guys that had P0304 (cylinder 4 misfire) code with symptoms such as rough hesitation, rough idle, loss of power, poor cold start, limping.

In my case, my subie threw out the P0304 code under hard acceleration either in 1st or 2nd gear at around 5k/6k rpm. I can than feel the mis-fire, but when I slow down or resume "normal" driving, the car runs perfectly fine. None of the rough idle or loss or power symptoms. My subie has been running very reliably for a very long time.

Just to be sure, I wanted to see if I can duplicate the code, so I accelerated her hard to try to duplicate the code and its confirmed that its happening on 1st or 2nd gear under hard acceleration. And, if I were to drive normally, it ran normal.

So I'm wondering if anyone out here had that same problem and if it might just simply be replacing the spark plug. So far, i'll attempt to change out the spark plugs (as they're due to be replaced anyways). Just wanted to see if there are other suggestions or past expereince from others here.

Also, what plugs do you guys suggest?

I'm running a stage 4 UTEC setup, vf34 turbo with STi pink injectors, Uppie & DP, borla hush.

I would run the NGK Iridiums, One step colder.

Mike

Hey Mike,

This is Waiman, but, its been a while since I've last seen you (dyno day) due to my wedding last year. I definately got to stop by your shop.

Thanks for the recommendation (spark plugs), but do you know of other situations where the P0304 code is thrown, yet the car still runs fine?

Waiman

lighter flywheel i've heard that throws it not sur tho

I see that this is the latest thread about CEL codes.

I'm having two right now...P0304 and P0037.

I put a fix on the O2 sensor and had Time It Lube reset the codes. Once that happened, my car stalled twice while slowing down to make a turn and then backing up. Not sure why that happened.

I'm going to get new plugs and wires but while reading other threads, that isn't doing the trick. I need to change them anyway so I'm going to do it. Also, the P0037 code states O2 sensor Bank 1 Sensor 2 Heater Circuit Low. Don't know what that means??? Anyone know?

Thanks for the help. In the meantime, I'm going to install new plugs and plug wires to see if I can fix the misfiring in cyclinder #4.

DrV

You don't have spark plug wires.The P0037 usually occurs when you have removed the rear O2 sensor or its unplugged.

ngk copper model bkr7es are the 1 step colder plugs.