Hi all,

My Ford Fiesta 2007 16v recently had the engine management light come on.  I had noticed that the car had started to judder a bit a week or two before the light came on.  When I got home from work, I plugged in the ODBII reader and discovered this error:

P0304 Cylinder 4 Misfire Detected

I did a quick troubleshoot, inspected the spark plug and the HT Lead as well as the top of the ignition coil.  All seemed visually fine.  I also switched the spark plug from cylinder 4 into cylinder 1.  Ran the car and checked the OBDII reader again.  I got the same error code (P0304). I noticed this time however, that there was a code pending too.  When I checked it was P0301 Cylinder 1 Misfire Detected.  (This may have been there during my original test but I did not notice it).

I would love some advice from you more experienced folks:

1. Do Cylinders one and four work as a pair?
2. If so, and I am receiving faults for both, what does this suggest the problem may be?
3. Could it be the initiation coil at fault? If so, how would I check?

Thank you in advance for your help, I really appreciate it!

James

If you moved the spark plug from cylinder 4 to 1 and then the fault code also moved from cylinder 4 to 1, then surely that means the spark plug is faulty, unless I have missed something?

As above this would probably indicate a duff plug, for the sake of a tenner I would stick a new set of plugs in....  

2 hours ago, nashdm2 said:

If you moved the spark plug from cylinder 4 to 1 and then the fault code also moved from cylinder 4 to 1, then surely that means the spark plug is faulty, unless I have missed something?

Sorry, I'm not sure if I explained myself properly.  I did move the spark plug from cylinder 4 to 1 but I'm still getting the error on cylinder 4 as well as an error pending on cylinder 1 according to the OBD reader.

Did you definitely clear all fault codes when you changed spark plugs around before you restarted the engine?