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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23821
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I have a 2008 F-150 with a 4.6 liter engine. I have a OBD

Customer Question

I have a 2008 F-150 with a 4.6 liter engine. I have a OBD device and have cleared codes, drove vehicle about a 100 miles and now have Codes, in order, P0174B, P0300B, P0302, P0306, P0307. I know 300 is random cylinder misfire, 302, 306 and 307 are cylinders #2, #7 and #8 misfiring. Recently replaced all plugs, checked for vacuum leaks. What am I missing?
Submitted: 5 months ago.
Category: Ford
Expert:  Jared D replied 5 months ago.

From the codes you might have a couple of ignition coils failing. You could try swapping the coils on cylinders 2, 6 and 7 with other cylinders to see if the misfire codes move around. Do you have a scan tool capable of monitoring fuel trims?

Customer: replied 5 months ago.
I installed a new coil on #2 as well as fuel injector. Was running it yesterday and pulled plug off #2 coil and engine noticeably dropped idle. #7 and #8 didn't seem to do anything when doing same thing. Will do what you suggested, clear codes and see what happens.
Customer: replied 5 months ago.
I have a J1587/J1708 & J1939 Heavy Duty Standard. Global OBD II. Would you know if this would do what your asking. Borrowed it from a customer and not familiar with it.
Expert:  Jared D replied 5 months ago.

I would probably try a compression test and see if any of the cylinders are lower than others.

Also, what brand of plugs were used when you swapped them out?