ok, quick summary to a very hard to find problem,

'96 X 302 with a hesitation/miss/stumble at low rpm and slight load on engine like a small incline.

i pulled out all my autolite plat plugs (fairly new) before a long trip this past weekend and found this: (NOTE TO SELF--pull plugs from both banks when checking plug condition!!!)

bank 1 (passenger side cylinders)
all 4 plugs looked great with slight wear, still gaped fine 0.052-0.054

bank 2 (driver side cylinders)
all 4 plugs showed MUCH more wear, gaps were opened to around 0.062, the inulators seemed to have a worn (maybe hot?) spot on each plug (looked like a single round worn spot on the insulator) also a small amount of chaulk like deposits on a few of these plugs' electrode side (the one you bend to gap).

so i cleaned and re-gapped. during our trip we noticed the problem (miss) went away. i couldn't make the miss come back. BUT then after a couple hundred miles, the miss is coming back, less, but still coming back.

SO...what do you guys think could cause the one bank of cylinders to cause advanced wear, white/gray chaulky deposits, etc. but not he other bank???

i know the coil packs are not divided by bank sides, but the O2 sensors are...i am getting no codes set, but wonder what can cause this condition??

 

Wow...that's weird. I'm sure there's more knowledgeable people out there than me, but here's some of my thoughts: At first I thought about head gasket leaking, but all four cylinders??? Unless you have a leak into the intake somewhere on that side, I would think that unlikely. Is antifreeze level normal? How about injectors? I have a caravan that had the same thing on one of it's plugs, but it was only on ONE cylinder. Injector cleaner fixed the problem. How about fault code's. Do you get the check engine light? I'm not familiar with your year of vehicle (my explorer is a 92) but if you have a pcv valve on the valve cover.. is it on that side? Does it check okay?
These are just some thoughts....not much help I'm afraid but I'll watch for a solution.

 

sjwoody,

thanks for the good suggestions, unfortunatly all of them check out ok...no codes, good seals, levels, etc.

this one has been stumping me for quite some time now. it is just recently that i found the uneven plug wear....this is a tough on.

the chances of just buying 4 bad plugs out of 8 is low, but then hitting that chance and installing them all on one bank?? not likely.

thanks again, any other ideas? a second look always helps!