98 Expd 4.6L
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Mountain Pass
Joined: Jun 2003
Posts: 137
Likes: 11
98 Expd 4.6L
Need some assistance here. My 98 4.6L expedition has 88K, and up to this point been problem free. Starting about 3 months ago the dreaded "spark knock" started under acc and downshifts. At that time I wrote it off to fuel quality. Progressed since then to a more audible knock under the same conditions. Check engine light has not come on. Took the vehicle to my local friendly 
ford dealer. Diagnostics resulted in no error codes. They replaced the spark plugs ($280) and conducted the 3 step carbon blast/injection cleaner. No luck. Coming back from the great north yesterday I thought the engine was going to detenate, I had the A/C on and in cruise mode. Every incline when the tranny downshifted I thought "Houston we have a problem" ........ knock, knock, knock, and loud it was.
Knock sensor??????? Any ideas? 89 octane a little better but still present.
ford dealer. Diagnostics resulted in no error codes. They replaced the spark plugs ($280) and conducted the 3 step carbon blast/injection cleaner. No luck. Coming back from the great north yesterday I thought the engine was going to detenate, I had the A/C on and in cruise mode. Every incline when the tranny downshifted I thought "Houston we have a problem" ........ knock, knock, knock, and loud it was.Knock sensor??????? Any ideas? 89 octane a little better but still present.
