i bought this truck last year at 154,000 miles. I've put 20,000 more on it with zero issues. Previous owner said had just done plugs and coils and injectors.

So today a plug ejects itself and break off the coil pack.

I got it back in and was on my way with no problems and no codes.

How often should plugs and coils be changed? How often should they be tightened?

thanks

 

What year is this EX?
Ford calls for plugs to be replaced at 100K mile interval, many DIY owners change them at 50K.
COPs (coils) only need to be replaced when proven to be bad, they either work or they don't. But again many folks choose some mileage point and change them out just for peace of mind, between 150 and 200K miles seems like a common range.
I don't have any info on any recommended torque recheck intervals, but with the earlier 3 thread heads giving them a recheck every 20K or so might be prudent.
It seems that those early heads benefit from running a higher than spec torque value to keep the plugs well seated over their lifetime. Do you happen to know what they were torqued to? 25/28 ft/lbs is the range that many owners have had good results with. What did you reset the blown plug to? Now that one has blown I know that I would be checking torque on them all very soon.

 

THanks,
The Excursion is a 2002. I haven't done anything yet except a road side repair.

I'll just tighten them up this weekend and call it good for a while. Truck runs too well to go looking for trouble,

 

Long story made short. Check that plug and make sure it is torqued to at least 25 ft/lbs. I know you'll be afraid of stripping the threads. If you can't get it to tighten its going to come out again. My Excursion is a 2002 also, and blew #9 with 210K on the original engine. The P.O. had the plugs replaced at 110K miles. When I investigated the trouble (on the roadside) I found bits and pieces of a coil that had blown before. This time the plug just got extremely loose. I didn't want to create a problem either, so I avoided "overtightening" that plug. I remember I tightened it to 15 ft/lbs. Big mistake, it blew again, this time it damaged the threads. I believe if I could have tightened that plug to 25/30 ft/lbs it would have survived. Notice I said "could have". I ended up replacing the engine with a new Ford long block with the long thread heads. The original engine ran extremely well also, but I decided with over 200K on the engine it was best to start over. Good luck.

 

Thats why i went with a fresh rebuild, and had them timesert all 10 during the build, it only cost me 4300 for a zero miles equivalent rebuild, including install, fluids, timeserting, engine painting to my specs, and even installing an all aluminum radiator i had drop shipped to the engine shop.

approaching 3500k miles on it and so far its been bulletproof

 

Install an insert that will never blow out again. TimeSert, CalVan/SnapOn, and Lock'nStitch are all excellent choices. Avoid all the HeliCoil, Dorman, and Save-a-thread cheap options.

Once repaired, re-torque all of the plugs, including the repaired cylinder, to 25-28 lb-ft instead of hte half-value that's in the books.