2013 F150 FX4 SCREW 4x4 5.0 MISFIRE ON COLD START
03-01-2016, 10:05 PM
#1
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2013 F150 FX4 SCREW 4x4 5.0 MISFIRE ON COLD START
Hi, I'm new to forum and hope I can get an answer. I have a 2013 FX4 SCREW
4x4 with 5.0. 158,000 highway miles on truck. Runs like new, quiet as a mouse with exception of misfire on cold start. Misfire disappears after engine warms up.
CEL indicating cold start misfire on cylinder 8. Ford dealer been working on different approaches for 3 weeks. Replaced all plugs with Motorcraft and gapped all to 0.045. Replaced all coils. Run a compression test--all good. Removed cylinder 8 side valve cover and video inspected. All good and very clean. Just had Terraclean Decarbonizing done and it is still doing this.
Any help would be greatly appreciated.
Thank you,
Bob
4x4 with 5.0. 158,000 highway miles on truck. Runs like new, quiet as a mouse with exception of misfire on cold start. Misfire disappears after engine warms up.
CEL indicating cold start misfire on cylinder 8. Ford dealer been working on different approaches for 3 weeks. Replaced all plugs with Motorcraft and gapped all to 0.045. Replaced all coils. Run a compression test--all good. Removed cylinder 8 side valve cover and video inspected. All good and very clean. Just had Terraclean Decarbonizing done and it is still doing this.
Any help would be greatly appreciated.
Thank you,
Bob
03-02-2016, 01:43 AM
#2
Senior Member
Intake gasket or other vacuum leak, is pretty common. Have them use a propane wand or carb cleaner around the number eight intake flange and the cylinder opposite in the firing order on a cold start and see if it goes away.
09-30-2016, 07:53 PM
#4
I always lean toward sensors first just because.
Temp sensors especially in cases where temperature is involved and everything else checks out. A bad temp sensor telling the engine that it is a temperature different than it truly is outside can tell the computer to enrich or lean out the fuel accordingly. If a temp sensor is bad, and telling the computer it's already hot, then it'll lean out the fuel. If it's telling the computer that it's cold when it's actually hot, it'll enrich the fuel and you'll notice a stronger gas smell at the exhaust. SOMETIMES. But it's a cheap place to start as far as troubleshooting.
Temp sensors especially in cases where temperature is involved and everything else checks out. A bad temp sensor telling the engine that it is a temperature different than it truly is outside can tell the computer to enrich or lean out the fuel accordingly. If a temp sensor is bad, and telling the computer it's already hot, then it'll lean out the fuel. If it's telling the computer that it's cold when it's actually hot, it'll enrich the fuel and you'll notice a stronger gas smell at the exhaust. SOMETIMES. But it's a cheap place to start as far as troubleshooting.
