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420a misfire and CEL

Posted by 95'RS-T, May 24, 2009

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  1. 95'RS-T

    95'RS-T Proven Member

    438
    0
    Joined Mar 10, 2009
    Germansville, Pennsylvania
    i have a misfire kinda like bucking and hesitation plugs are new as well as coil and wires the MIL light is on with 2 codes one is for the down stream o2 sensor and the other is p0412 i know its something with the AIR system Im just wondering if this would cause the misfire. any input would be great BTW the o2 sensor was taken out after my turbo down pipe was installed and still had the same problem before i went turbo thats why i replaced wires, plugs, and coil. o2 sensor was new as well
     

    376  0

    1995 Mitsubishi Eclipse GST
    · 2G DSM
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  2. bagged420a

    bagged420a Proven Member

    289
    3
    Joined Oct 7, 2008
    Huntsville, Alabama
    did you make sure to gap your plugs?
     

    617  0

    1995 Mitsubishi Eclipse N/T
    manual · 2G DSM
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  3. 95'RS-T

    95'RS-T Proven Member

    438
    0
    Joined Mar 10, 2009
    Germansville, Pennsylvania
    yes there gaped at 32
     

    376  0

    1995 Mitsubishi Eclipse GST
    · 2G DSM
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  4. 95'RS-T

    95'RS-T Proven Member

    438
    0
    Joined Mar 10, 2009
    Germansville, Pennsylvania
    bump
     

    376  0

    1995 Mitsubishi Eclipse GST
    · 2G DSM
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  5. dented_coffee

    dented_coffee Proven Member

    510
    12
    Joined May 14, 2009
    West Branch, Michigan
    P0412 Secondary Air Injection System Switching Valve A Circuit Malfunction. make shure your wires for the maf are not corroded and plugged in. if your using a maf translator for the gm maf it might be a bad maf or translator chip. i had this problem with my car misfiring and sputtring it was because the maf was messed up. also make shur your intake isnt cracked (take a can of eather aka starter fluid and spray arround and on the intake manifold. if the car get a higher rpm for a second or it sounds like it wants to bog down. you have a leak and its causing your engine to take in way to much air). O2 sensors shouldnt cause your car to misfire if there bad they just make your car burn unnessisary amounts of fuel causing your MPG's to go out the window. i have been working on mitsubishi eclipse's ever seens i was 7 years old and im in college at this time halfway threw my masters degree in all around automotive. remember trust the pros not the hoes.
     
  6. 95'RS-T

    95'RS-T Proven Member

    438
    0
    Joined Mar 10, 2009
    Germansville, Pennsylvania
    thats funny but i hate to tell you this but the 420a dont have a MAF
     

    376  0

    1995 Mitsubishi Eclipse GST
    · 2G DSM
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  7. skittlezfersur

    skittlezfersur Proven Member

    33
    0
    Joined Apr 29, 2014
    winchester, Virginia
    same issue with my car that code shows up when i hook up the obd it boggs like he said and then revs really high then shuts off I've been working on thiss car for about a year now that i got another motor n it does the same darn thing every sensor is new i thought the heater core was done so that was replaced but its been the issue with the air injection the hole time
     
  8. Tom Gibbons

    Tom Gibbons Proven Member

    45
    4
    Joined Mar 22, 2015
    Beecher, Illinois
    Make sure your plug wires are in the right firing order on the coil pack. 4123 from passenger side to drivers side
     

    Street Build 1K  0

    1999 Mitsubishi Eclipse GST
    manual · 2G DSM
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  9. ThunderChild

    ThunderChild Supporting VIP

    2,541
    710
    Joined Jan 5, 2012
    Rathdrum, Idaho
    check your map sensor on the IM, the port for it could be clogged. also check/replace your CKP (crank position sensor) as it deals directly with ignition timing and is prone to oil contamination (it is located on the back of the block, close to the oil filter location)

    after that, i might start looking at your injectors/fuel filter and pressure reg (should be returnless so the regulator setup is located on the tank)
     

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