#5 spark plug literally burnt a hole through. What's the cause?
1999 Jeep Grand Cherokee, 4.0 V6 (Laredo)
Did a tune up, replaced spark plug, spark plug rail and fuel injectors. Ran fine for about
60 miles and then check engine light came on, lost pressure.
Had the same problem with a 64 Saab 2-stroke - the spark plug literally burned a hole through the top of the piston. The plug was way too high heat range. For many years, I kept the piston with the spark plug sitting in the hole it had burned,
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