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Misfire code but not misfiring.

Discussion in '1st Gen Tundras (2000-2006)' started by Mytechguyri, Feb 17, 2020.

  1. Feb 17, 2020 at 9:24 AM

    Mytechguyri [OP] New Member

    Dec 6, 2018
    First Name:
    2004 Tundra 4x4 Access Cab step side
    My 2004 4.7l has been throwing P0300, P0305, P0308, only when first started in the morning.

    You'd think the truck would run crappy, but it purrs, and has plenty of power.

    Here's what I've done so far to fix this.

    1. Replaced all spark plugs with Denso OEM
    2. Swapped cylinder 5 and 8 coil packs to their adjacent cylinders... The misfire code did NOT move, so assuming the coil packs are good.
    3. Seafoamed intake
    4. Replaced bank 1 upstream and downstream 02 sensors and cat (cat confirmed tested bad)
    4. Compression checks out ok
    5. Cleaned MAF sensor w/spray maf sensor cleaner
    6. Replaced all 8 fuel injectors yesterday with remanufactured Denso injectors.... had a P0302 on initial startup after installing the injectors, cleared that and it hasn't come back, so no misfire codes the rest of the day, much more responsive acceleration... Figured great, got it.

    Nope.... This morning... Started right up, running smooth, but check engine light starts flashing... Sure enough... P0300, P0305, P0308

    My next step im thinking crank sensor? Outside of a bad ECU, I don't know what else it could be.

    Any advice/suggestions at this point is appreciated.... I love my truck, but chasing this problem is getting frustrating and expensive.
  2. Feb 18, 2020 at 6:34 AM

    N84434 In the Frozen Tundra

    Jan 22, 2020
    First Name:
    Milwaukee WI.
    2001 Limited TRD
    I'd check those plugs for signs of arcing from the coils. Make sure there's no pooling oil around the plugs as well. Have you had the intake off? Check for potential vacuum leaks too....

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