first, the **** poor design is the fact that dirt or other debris can fall into cylinders. i didnt say it was hard to change. second, i am not a novice mechanic, and yes i tried putting the old plugs back in, same thing. no i didnt blow out any spark plugs or strip any threads. as far as torgue, 12ftlbs. really isnt that much, so yes i would say they are torgued enough. no pistons hitting bottm of plugs, gauge shows great oil pressure, cam chains seem good. i only have 85000 miles on her, easy driven miles, mostly. i have opened her up to see potential a couple of times, but it has been years since any serious rpms. she has been in garage for about 2 months before i started t6o work on her. so with that out of the way, does any one else have any ideas as to what could be problem. one last bit of info. before it was parked, the idle problem only happened a couple of times, she ran great otherwise

 

I would always spray air around the plugs to clear out any debri before changing plugs.

anyway to get a video of it running?

 

The plugs gapped properly? even if the plugs are pre-gapped I always check them. Other than that sounds to me like what everyone else said, piston hitting or blown plug...

 

Well at first you should take some can air or a air hose and blow out any debris that may be there once COP is removed ,as for the design its no different then the GM LSx motors.
debris can fall in those spark plug hole as well. That goes for any "Hemi style" engines.Btw that can happen to ANY engine.



My guess if you didnt do this to start before ripping those plugs out something fell into spark plug hole and may have done damage.

If you put your old plugs back in and it still did the same thing and something fell in spark plug hole , the damage done may have been already and its too late.


GL

 

If you keep the engine clean there will be nothing to "fall in".

Sounds to me like we're not getting the whole story...

 

maybe you left a day laboring ese under your hood from your last visit across the border??

 

I'm thinking this could be the culprit. Improperly gapped (too big of a gap) sparkplug.

What were they gapped at OP, or did you check at all? It's a simple oversight but can cost you dearly.

 

I bet its carbon knock. Carbon built up on the valves and a chunk fell off and causes a knocking noise in the cylinder. This could be caused from higher rpm driving or a larger than usual spark. Thats my best guess. Try seafoaming the car to see if that helps at all.

This is caused by very gentle driving as well...so the grandma driving its been seeing might be the culprit.

 

Did you run the engine before changing the plugs, or change them after sitting for 2 months and then start it?