po303 what is it and what replace

[chuck ray]

po303 what is it and what replace

 

[RonD]

Ford P0300 is a general random misfire code

Ford P030X is a specific misfire code, the X is the cylinder number that is misfiring, so .....
P0303 would be misfire on cylinder #3

First thing I would ask is, Is the engine really missing?
Does it miss only at idle or only while driving, or only while driving up a hill(under load)?

Could just be a dirty or bad spark plug or faulty spark plug wire.
Could be a dirty fuel injector.
Could be coil problem.
Could even be a bad valve or head gasket.

I would first reset the computer, unhook battery's Black(-) cable for 5 minutes or use OBD II Reader to reset, then hook it back up and go for a drive, time how long it takes for P0303 to come back, check engine light comes back on.

 

[chuck ray]

Ok truck cooled down went outside cranked it up ran fine drove a couple miles engine running fine

 

[RonD]

Could have been a dirty injector.
Change the $10 fuel filter if it is the original one.
And put a can of Seafoam($8) in the gas tank, I do this once a year on all my fuel injected cars, you will notice a difference.

If miss comes back when engine is warm, it could be a spark plug, wire, or coil, all can be effected by heat.
You can swap spark plugs, i.e. #3 to #2, and see if code changes to P0302
Coils are harder to check

 

[chuck ray]

ok drove it 10 minutes no problem then it started missing again

 

[adsm08]

Coils are harder to check

No they aren't, just flip the wires from side to side on the coil.

For some reason that is beyond me usually only one tower of a coil will fail. If the coil is bad the miss will move.

 

[chuck ray]

New plugs and wires still misses when it gets hots