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Paulson's avatar
Paulson
Explorer
Sep 23, 2021

V10 misfire codes

We recently purchased a 2016 Fleetwood bounder with a Triton V10. On the way home on a 20 minute drive, the check engine light started flashing. Codes were P0300, P0302, and P0306. Since then on various test drives, it has popped all of the even numbered misfire codes 02 thru 10. It has never popped an odd numbered misfire code. Found out about a TSB, so took it to the Ford dealership to have the PCM software upgraded. However they informed me I already have the upgrade. We have replaced all 10 spark plugs and coils. I have checked the PCV valve hose for leaks. I have replaced the MAF. The check engine light will typically flash after having been under load, and then I back off on the Accelerator So after going up a hill, it will not flash until I take my foot off the gas, and then it will flash going down the hill. I am stumped, especially considering it only pops even numbered misfire codes. Any input would be appreciated!
Class A
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Sep 23, 2021
    You need a code reader that can access "live data". Shooting the parts cannon gets expensive quick.

    First thing to look for (besides the misfire) is short and long term fuel trim. I'll bet he side still misfiring has a large positive long term trim. This indicates an air leak. If only on one cylinder it could be a bad injector.

    Stop shooting from the hip !
  • path1's avatar
    path1
    Explorer
    Sep 23, 2021
    I have a little brother a 5.4 I had problems with mine throwing codes after chasing down all the stuff and getting injectors cleaned excetera excetera neighbor asked when last time I cleaned throttle body, found something on YouTube followed it and fixed the problem. Also I checked all electri connectors up near the throttle body maybe there's something to do with that also not sure
  • enblethen's avatar
    enblethen
    Nomad
    Sep 24, 2021
    P0302 and P0306 are cylinder 2 and 6. Probably coil packs
    P0300 is random miss fire. Commonly goes away when coil packs are replaced.
    What brand of coil packs did you install? Many are not worth much inclding factory ones from Ford.
  • theoldwizard1's avatar
    theoldwizard1
    Explorer II
    Sep 24, 2021
    enblethen wrote:
    P0302 and P0306 are cylinder 2 and 6. Probably coil packs
    P0300 is random miss fire. Commonly goes away when coil packs are replaced.
    What brand of coil packs did you install? Many are not worth much inclding factory ones from Ford.

    I would agree with stick with OEM (Motorcraft), but OP says they have been replaced.
  • zigzagrv's avatar
    zigzagrv
    Explorer
    Sep 24, 2021
    How is the chassis battery/connections? When my battery started going south, I would get random multiple misfire codes for a short time after startup. New battery solved that.
  • Dale_Traveling's avatar
    Dale_Traveling
    Explorer II
    Sep 27, 2021
    Do a vacuum leak check by spraying around the intake manifold and throttle body with carb cleaner. If you have a leak it will suck in the cleaner which will change the idle slightly.

    If you can find a leak and the fuel trims are wacky then swap O2 sensors and see if your P codes change to the other cylinder back.
  • way2roll's avatar
    way2roll
    Navigator II
    Sep 27, 2021
    Similar issues on my previous F150 with a 5.4. I ended up getting an ODBII reader with the torque app. It shows real time data. Misfire rates for the ford engines have thresholds that may/may not throw a code. But the torque app allows you to see that actual misfire rates and pinpoint the exact cylinder. Usually it's a coil pack. I actually started carrying extra in the truck and could swap it out in 5 minutes. One trick I did that seemed to stop the problem was a liberal amount of dialectic grease on on it before installing. The plug wells are deep on those engines and hold moisture which I think contributes to the fouling. After I started to do that, I never had the issue again.

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