With 130K miles on the ticker (and a bit of a rough idle), it was time for plugs/wires/coils on the family truckster. Since RockAuto shipped everything here post-haste, I figured tonight was a good a time as any to dive in much to the chagrin of my bride.
I had replaced the OEM copper Champion plugs @ 30K miles with dual platinum plugs (they were burnt out to nearly 0.080" gaps !), but 100K miles is a lot of sparks even for platinum plugs, especially considering this engine fires wasted spark (for emissions). That means the plugs fire at every TDC versus just the compression stroke TDC.
You might not think replacing plugs/wires/coils would be a big deal, but we're talking a 2004 pre-MDS Hemi here with the 'brilliant' ignition system that has 16 plugs, 8 wires to run across to the opposite cylinder, and 8 coil-on-plug modules. I am not sure why they over complicated things with this setup, and subsequent Hemi engines have just 8 coil-on-plug modules that fire both plugs for each cylinder (no ignition wires)...
To add to the insanity, the packaging of the 5.7L in the Durango is pretty tight. I am over 6' tall and I was on my tippy toes reaching the hardware on cylinders 7 & 8. To get access to everything, you need to remove the intake zip-tube, resonator, crankcase breather hose, and EGR tube. Cylinders 7 & 8 are so far back under the cowl and jammed next to the refrigerant lines (pass. side) and brake booster (driver side) that you have to drop the plug socket, and two 2.5" extensions in one by one because there is no room. Just removing the coil modules requires a 1/4" drive ratchet and patience. Long sleeves and good mechanics gloves are a must to avoid cuts and scrapes. [Sorry, no SR20 midway through b/c I was focused on finishing without screwing anything up.]
The Dual Platinum plugs I removed were actually in decent shape. Relatively clean, and gapped at about 0.060", which isn't bad at all considering the mileage. I put in Dual Iridium plugs, so I think I am set for the rest of the useful life of the truck.
I fired up the Hemi for a quick functional check and all was good - no more choppy idle. Mission accomplished in just about 3 hours. Time for some adult beverages.
All of the stuff cost just over $300 from RockAuto - they had the best combined price of any of the sources I researched.