You can't expect plugs to be gapped correctly after 40,ooo miles. Electrodes wear down. Gaps get wider.Just thought I would let everyone know just in case. Check the plug gap before installing new plugs. I bought 4 new AC Delco plugs for my 2014 1.4L that were supposed to be pre-gapped at 0.028 They were not! All of them were wrong ranging from 0.022 to 0.024
A simple $1.50 tool was all I needed to confirm it and fix it.
Furthermore when I removed the stock plugs from the factory (car has 39800 miles) the gap was wrong as well. The car is running much better with the plugs gaped correctly. I wonder if the assembly line just slammed them in there without caring
It's called wear and tear.