2009 MS3 CEL P0303

Discussion in 'Mazdaspeed 3 Troubleshooting' started by ChadG, Feb 11, 2024.

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  1. ChadG

    ChadG Greenie N00B Member

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    Location:
    Moreno Valley
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    Year/Make/Model: 2009 mazda mazdaspeed3
    Mileage: 123800
    Location: Norco, CA
    Concern: Car is running fine but throwing a CEL for a cylinder 3 misfire
    DTC's: P0303
    Modifications: none
    ECU/Tuning Software: none
    Tuner: none
    Is the concern intermittent? No
    Can you duplicate the concern? Yes (CEL is consistently turning on, but car doesn't experience any drive ability concerns)
    Recent Repairs:
    checked gap on spark plugs (all are fine)
    Swapped plugs onto a dif cylinder
    Swapped coils onto dif cylinder (code stays on 3rd)
    Put on new vacuum runner solenoid valve
    Checked for leaks with soapy water
    Note: new fuel injectors were put on approx 6 months ago
    Correction: Please help!!!
     
    ChadG, via a mobile device, Feb 11, 2024
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  2. Raider

    Raider Administraider Administrator Platinum Member

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    0.026-0.028 gap, non Amazon sourced NGK plugs. Compression and leak down test time. Then look at the injector and also valve cleaning if not performed.
     
    Raider, via an iPhone, Feb 12, 2024
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  3. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    check the wiring to the coil pack and in particular make sure none of the pins are pushing out of the connectors
     
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  4. ChadG

    ChadG Greenie N00B Member

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    The current plugs are newer and gapped correctly and are not amazon sourced. I also swapped plugs to different cylinders and the problem stayed on cylinder 3. Did a compression test and the compression is within normal ranges on all cylinders. Check fuel pressure as well and they are all consistent and within normal ranges and they are new injectors. Still drawing a blank here

    Check the coils and nothing seems to be wrong. Also swapped the coil onto a different cylinder and the code stayed on #3. Just not sure what else to do
     
    Last edited by a moderator: Feb 19, 2024
    ChadG, via a mobile device, Feb 19, 2024
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  5. Awafrican

    Awafrican Moderator Gold Member

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    Leak down test time. What exactly were the compression numbers?
     
    Awafrican, via a mobile device, Feb 19, 2024
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