P0301 Misfire Detected in #1 Cylinder

Please forgive me as I can not type Chinese on the PC I am using.

Background:  About a year ago I replaced the 4 spark plugs for my 2012 Subaru Legacy. It took me a while to unscrew the old spark plugs and took them out but when I tightened the new spark plugs pretty soon I felt it was already tight and I did not go any further because I did not want to overtighten them.  Several days alter my check engine light was on and the code was P0301 Misfire Dected in #1 Cylinder. I tried to tighten the spark plug again but it was still pretty tight so I just erased the code and the car was running fine for about a year. 

recently the code P0301 came back again and if I erased it the check engine light will turn on again the next day. Now what can I do? I can bring the car to a dealership but just feel it is stupid if the problem is the spark plug is not tighten enough. Should I just try unscrewing the spark plug and tightening it again and see how it goes?  Or should i just let a mechanic to handle it?

 

Thanks!

Swap it with another see if you get the same code

最好用torque wrench按Spec上紧，但是你的问题不像是没上紧吧。

第一，Engine哆嗦吗

4缸车丢一个肯定要哆嗦，这个症状不大可能错过。

第二，说是第一缸，未必就是第一缸。所以每个缸的spark都要看看状况。

第三，Coil接线是否正常？coil是否还工作？需要测一下。

you mean swap spark plugs? for example switching 1 and 2?

no shaking or exessive vibration. Should I still check coil?

can the fuel line clogged causing not enough fuel?

换一下1和2的Coil看看；跑了多少迈了？可能Coil该换了

一年多没事，大概率不是松紧的问题，最忌火花塞拧过头；单缸失火有两个最大可能，火花塞和点火线圈, 找一个对照缸，分别调换

比如缸1缸2火花塞互换，消码，看看错码是否出现于缸2，如果是，就是火花塞的问题，如果仍是P0301, 那基本是线圈了，同理Coil点火线圈互换，看错码是否跟随

 

also got both P0301 and P0303 at one time

I forgot to mention once I got both P0301 and P0303 although most of the time it was just P0301. 

thanks, will do

focus on 301 first, 303 might be caused from it