code p0305

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Oct 11, 2020 | 08:21 PM

Jerry Kendall

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code p0305

I own a 2013 F 150 with a 5.0 litre engine. Recently a check engine light came on so I had a friend put his diagnostic tool to work and it showed a misfire on cylinder 5 at idle. He cleared it and after a couple of days it was back. My first thought was spark plugs. I had 139K miles on it and it looked as though the plugs had never been changed. I bought the truck used so I wasn't sure. I changed the plugs, nothing changed. I couldn't feel any hesitation or miss while driving but it idled a little rough. My next thought was the coil, I should have just swapped #5's for one of the others to see if the coil was bad but I just bought another coil and replaced it. Nothing changed. Ok, must be the fuel injector, nope, changed that nothing changed. any ideas where to go next?

Oct 11, 2020 | 11:40 PM

Johnny Paycheck

Fleet Mechanic

Joined: Jul 2019

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You need three things to avoid a misfire. Fuel, spark and compression. Check compression next.

Oct 12, 2020 | 09:52 AM

alloro

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Ditto on the compression check. If it checks out okay then you likely have a issue with the wires going to the injector or coil. As a last resort the ECM could be failing.