Eating spark plugs

[MikeK]

My 99 XLT V6 (not OHC) has a problem I haven't seen posted anywhere, and I have had no luck with two shops to end the problem.

We purchased it used from a Ford dealer who claimed it "just had a tune-up." Shortly after, it began to run rough on start-up (could be hot or cold, no difference and always at random) that went away after about 10-15 seconds. As time goes on, the problem worsens, lasting longer and happening for frequently.

Eventually the check engine light comes on. Both shops, and myself after using the free tool at Checker/Schucks/Cragen tell me that the #3 cylinder has a miss. I have replaced the plug wires and the plugs, which correct the problem for awhile, but then it returns after a couple of months. I have also had the fuel injectors cleaned (using 2 cans of cleaner attached to the shrader valve on the fuel rail).

Every time, the #3 plug looks like it's been in there for about 250 thousand miles! I can keep replacing it, which fixes the problem, but would like to know if someone out there has seen this before and can help. Also, I feel dumb for asking, but which plug is the #3? I'm assuming its the (driver's) left rear?? Thanks.

 

[ExplorerDMB]

Driver side rear on a Ford is #6! Here is a chart:

First off, who did the tune-up....you or the shop? Be sure to check the gap on the plugs. Also, get a scanner and see if you are running rich. Possibly an O2 sensor is causing your problem. Just adding so much fuel that is pretty much covers the spark plug and won't fire right. I'm sure someone on here can give you more information or a direction onto where to go.

-Drew

 

[Billy177]

clean teh maf and try some seafoam, chances are it is pinging in that cylinder destroying the spark plug

 

[MikeK]

Thanks! I'll change the plug myself and at least be able to drive it for awhile again! I had two different shops do the work. I have worked on older stuff, but the combination of computer control and busy work kept me out from under the hood on this job!
-mk