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420A P0300 Please Help I've Done Everything/Seached

Posted by mitecl96, Oct 26, 2016

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  1. mitecl96

    mitecl96 Proven Member

    Joined Feb 20, 2012
    McMinnville, Tennessee
    96 Eclipse 420a Manual.

    Can skip to the bottom to see a list of what I replace without reading the story.

    I am going to post everything I've done this year. At the first of the year my car was having a randomly dying issue, would just shut off while driving and wouldn't fire up. It would crank but no fire. First thing I replaced was the ignition switch. That didn't fix it so went to the next common issue and replaced the Crankshaft Position Senor with no luck. I tired to figure out if I was losing spark or fuel but by the time I got help the car would start fine again and I never had any codes. I suspected spark and redone the ignition system. New plugs, wires, coil pack, and then Camshaft Position Sensor. Again had no luck so I decided the give the Crank Sensor another shot and still nothing. Well after all I did I went to the fuel system. New Fuel Pump, Filter, and pressure regulator. Nothing and at this point I would do anything. Next things I did was the temperature sensor both air and coolant, then got another known good ECU. Lastly I pulled the engine Harness and found some melted wires due to the egr tube. Redid a lot of the wires on the harness, and replaced connectors that I could get. Really felt like I had found my problem till it died again. My gut was telling me to try the crank sensor one more time and I'll be damned if that was the issue. 2 new bad crank sensors. (Sums up my luck)

    Well at this point I needed to get tags updated so I needed to run through emissions. Been running the car for a month to make sure I had fixed the problem. Then one night driving to my friends house an hour away (Which I have went to a million times that month) the check engine light came on with my least favorite code. P0300. Got to his house and next day we replaced plugs and wires with new and the coil pack with my old one. Cleared the code and later that night went back home. Well hell broke loose on that trip. #3 rod bearing spun and the my throw out bearing failed and took the clutch with it. (before you thing I drive like a mad man with this car I don't. I know the car is not fast, never will be, but I drive it like a regular daily driver. The car very rarely sees over 3,000 RPMs)

    Well decided that I already have to replace the clutch I might as well see if I can't find another motor. Went to a pull a part found a motor that spun free, checked the plugs and all seems good. Got the motor home and while it was on a engine stand I replaced the time and also replaced the rod bearing (I have bad luck when it comes to rod bearing). Got the car back together and it was running great but still was having that P0300 code. Drove it to my friends house the next day and as we left his parents house the timing failed. I wanted to cry. Decided I was going to warranty out the timing kit and use my head off my old motor.

    I pulled off my old head and replaced the valve seals and re-lapped the valves. Everything looked great so off to my friends house to get my car fixed. Talking about bad luck when I started to pull the timing apart I found out what happened. The Bolt that the tensionor idler bracket pivots on broke. Well got the head off and that made me sick. The motor I pulled from the junk yard was new. No oil staining anywhere on the head, not even carbon build up on the valves, combustion chamber, or pistons. All new.

    Got it running still had that p0300 code. Changed plugs again, switched back to my old ECU, even replaced the EGR valve and fuel injectors. Cleaned the throttle body still have the code. Checked fuel pressure and compression. All good and Compression was 150 on all 4 cylinders. Now that catches everyone up to the battle I have with my car this year.

    I can clear the code and drive all week in town (Max speed 50mph) and the code will never come on. Drive down a highway minimum of 60 mph and the code will pop up after a few miles. Only code I have gotten is P0300.

    Here is a list of everything I have replaced:
    - Spark Plugs
    Plug Wires
    Coil pack
    Crankshaft sensor (Mopar)
    Camshaft sensor (Mopar)
    Coolant Temp. Sensor
    Air Temp. Sensor
    Map Sensor
    Engine harness Redone
    Fuel Pump
    Fuel Filter
    Fuel Pressure Regulator
    Fuel injectors
    EGR Valve
    No Vacuum leaks
    New Catalytic Convertor (Replaced a year ago, Checked back pressure, tested Fine)
    150 Compression all 4 Cylinders
    Fuel Pressure 45
    Up and down stream Oxygen sensors (denso)
    Ignition Switch
    Timing checked dead on

    Street Build 806  4

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
  2. spyderdrifter

    spyderdrifter Freelancer

    Joined Jul 11, 2009
    Fountain, Colorado

    1K  2

    1996 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    1K  3

    1995 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM

    1K  5

    1999 Mitsubishi Eclipse N/T
    automatic · 2G DSM

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