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P0401 along with misfire code P0301

Discussion in '7G Lancer and older- General Information' started by SilentCool, Feb 18, 2014.

  1. SilentCool

    SilentCool Well-Known Member

    I believe my misfire is caused by my egr valve or somewhere in the system. I have been trying to rectify an egr problem for a couple months now - getting a P0401 egr flow insufficient code. I decided to tackle this issue myself by running a few tests referring to the service manual since none of my egr system vaccum lines were loose or disconnected. Everything checked out fine, I believe there was one more test for me to carry out but didn't get the opportunity to complete that test. Somehow, fiddling with all vaccum lines did the trick or at least I thought so. I ran the car for about 250 miles with no issue. Yesterday the car was bogging, almost dying below 1000 rpms. I pulled to a side street parked up and looked under the hood. Basically, I just did the general check up to see if anything was loose or out of place. Couldn't find the issue. After a few revs the issue disappeared and idle was back to normal, I put some injector cleaner in the gas tank, assuming it was a gas issue. The only thing I did right before this issue appeared was fill up at the pump. Last night into the early morning omw back from work after getting off the highway the issue returned, this time I got a CEL with a P0401, P0301 code which leads me to believe that my egr valve is complete toast and it is causing a misfire on cylinder 1. If anyone can shed some light, all help will be greatly appreciated.

    P.S. I have tried cleaning/removing carbon build up from the valve itself a few months before. My next step was to remove the intake manifold and try cleaning it out.
     
    Last edited: Feb 18, 2014
    SilentCool, Feb 18, 2014
    #1
  2. Metalsoft

    Metalsoft Member

    I would replace the EGR valve and both 02 sensors. That should fix your problem.
     
    Metalsoft, Feb 24, 2014
    #2
  3. SilentCool

    SilentCool Well-Known Member

    Thanks for the advice, any reason why you suggest the O2 sensors? My EGR valve came in the mail so I should be installing soon. Will report here with an update
     
    SilentCool, Feb 24, 2014
    #3
  4. Metalsoft

    Metalsoft Member

    Well this is my own theory I formed from experience. With a bad EGR valve that has been giving you problems for a few months, here is what I think happened. With that cylinder misfiring, it is dumping unburned gas through your system. This gives you a really bad carbon buildup, hence once you fix the EGR valve, I would highly suspect that the O2 sensors will start throwing a code. These cars are quite sensitive to the sensors. To me it would be more of a PM ( preventive maintenance type thing ).

    I also had o2 sensor problems and they are easy to change are only about $40 a piece. The front is plug and play, the second one up under the car, is a bit tricky. The one I bought did not come with the connector so I took out the old one and soldered in the new to the connector.

    These things kind of go hand and hand. If it was me this is what I would do..... EGR valve - front o2, rear o2, clean OR replace spark plugs.

    After that, she should idle and run like a dream.

    Good luck and let me know if you need any advice.
     
    Metalsoft, Feb 25, 2014
    #4
  5. SilentCool

    SilentCool Well-Known Member

    Got you! I understand & agree. Thanks again, I will definitely let you know how everything goes.
     
    SilentCool, Feb 25, 2014
    #5