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I have a 2006 ford f150 with 5.4 and 270000 miles and the other day I had a misfire on cyl 3, I changed all ign coils and spark plugs now I have a code po0353 and still rough idling, and poor power when driving, the code says cyl 3 and second circuit, what could be causing this
In determining the cause, it is important to note: The misfire DTC reporting is cleverly divided into two distinct categories by the PCM. The P035x series is 'electrical' oriented. ie: The PCM checks for current draw in the COP circuit and the reverse electrical 'kickback' that occurs in the primary circuit when the spark plug 'SPARKS'. In either case, the PCM was electrically unable to create a 'SPARK' and thus the cylinder could not have fired. Is that technically a misfire? On the other hand, the P030x series is reported when the first test is successful (meaning there was a 'SPARK' event detected), BUT the PCM failed to detect the slight acceleration in crankshaft rotation speed that is expected when the 'detonation' of fuel air is exposed to that 'SPARK'. This commands quiet a different diagnostic path. Such as fuel delivery, or fuel/air mixture, or compression, or valve timing ---- etc.
In your case, focus should be on the electrical sides inability to create a spark. Check COP plastic connector snap, continuity of secondary wire to PCM. Could even be a defective plug 'out of the box'. We have seen that here more than once.
A simple test is to remove the offending plug - install an old spare plug into the cylinder temporarily. Connect the COP primary and Insert the offending plug in the COP boot. Ground the plug cathode with a jumper. Start the engine and try to get it to spark like it is supposed to.
I have a 2006 ford f150 with 5.4 and 270000 miles and the other day I had a misfire on cyl 3, I changed all ign coils and spark plugs now I have a code po0353 and still rough idling, and poor power when driving, the code says cyl 3 and second circuit, what could be causing this
Coil #3 connector loose or broken.
Signed up in 2011, this is one of just 2 posts in 9 + years?
I went back and checked cool and some how the connection on the coil was broke replaced with one of the old coils and problem went away so another new coil to replace it with, thanks for the help guys
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