A block short of work, it seemed as if all cylinders were not firing and flashing CEL came on. After taking care of important stuff, I headed home. On return trip Track light came on and I could tell that I was getting 5/6 power and transmission was not getting into overdrive. Since I was about 140k on original plugs, I picked them up on the way home.

Hooked the scanner and it gave a code cylinder 4 was misfiring. When the engine cooled down, I replaced all 6 plugs. #4 tip was almost gone and only thick part of the electrode was left. I fired the RX up and could tell that one cylinder was not firing. Hooked up the scanner and now it said misfire on 5.

I undid 5 and checked the coil pack 5. No spark! Quickly ran over to dealership and picked up the part before they closed. Installed it and every thing is fine now except I have lost the screw for the cover hold-down. I will look for it later.

Now the thing that confuses me .. if coil pack 4 had gone out, it would have made more sense. Before some one suggests that I could have mixed up the coil packs .... I totally closed 2, 4, 6 before opening up 1,3,5.

Is it possible that the new plug (stronger spark) overloaded the weak coil-pack?

Salim

 

I don't have an answer. Just curious, how did you test #5 for spark? How many miles do you have on those plugs?

 

Pulled the coil-pack of #5 out and pulled the new plug out. Stuffed the plug in the coil-pack and placed on the engine head. When engine was cranked ... no spark. Pulled the coil pack of #6 (just because it was easy). Stuck the spark plug in and got good spark. Switched to coil-pack from 5, no spark. Conclusion, coil-pack #5 is bad.

A similar test was done when we had spark plug wires go directly to spark plugs. Now you have to insert the coil-pack in between.

The originals were almost at 140k.

Salim

 

Salim, it's possible to occur what you just mentioned. In fact, such an almost similar issue occurred not too long ago with my girlfriend's Expedition.