I have a Ford 1.6 EcoBoost Turbo 150 HP petrol engine. The car started misfiring, and a diagnostic scan showed a random misfire as well as a misfire on cylinder 4. The spark plugs were replaced with new NGK spark plugs. However, after starting the engine, the check engine light came on, and when I turn on the A/C, the engine vibrates very badly.






After running another diagnostic scan, the misfire fault is now showing on cylinder 2 instead. I would like to mention that the ignition coils are installed correctly.

What could be causing this issue?

 

What year? And are you in the US/Canada?
Check my signature below.
And which exact scanner are you using?
So you have a check engine light AFTER you changed your spark plugs?

 

Did you replace the spark plugs one at a time or all at once doing the same bank?

Easy to mix up 2 wires that look right and yet may not be !