pcdtmurray

Update - The problem continued to get worse so rather that just do boots & springs, I decided to replace all the coils. The original coils (3L3E-12A366-CA 7C 1452) had 105 K on them and were 9 years old. I replaced them with Denso 673-6003. These were listed as "OE" on the Rockauto website. Took about 90 minute. This solved the problem. I did notice 3 things while removing the original units. About half of them had some white oxidation on the end of the spring. The boots appeared to be in excellent condition. nearly all the springs just reached the end of the boot while the new coils had the spring extending 1/4"-1/2" beyond the end of the boot.


Thanks to all that offered advice!

F150Torqued

That oxidation is kinda' like the stuff that used to get on the terminals of the "AA" battery in our transistor radio and make it to quit working! And it is the type 'subtle' things that result in increased resistance to spark current and poor mechanical contact occasionally.


These engines run so lean - with lots of emissions EGR going on, everything has to be almost perfect.


Appreciate the update and glad for your success