Have a 2000 Ranger 2wd 3.0L flex fuel w/ 40,000 mi. Recently started running and idling rough. Only time itruns smoothis in hard acceleration. On investigation I found that it had one spark plug not firing and judging by the lack of wear on the dead plug compared to the normal plugs, it had not fired for a long time. However the bad plug was clean with no deposits or fouling on it.
When I replaced the bad plug, I unfortunately detected no change in the engine. It still runs and idlesrough. Could I have a plugged converter from all the miles driven with one cylinder missfiring? Could any one please bail me out?

Thanks in advance,

Rancher

 

Or possibly a bad injector? you did say clean as in no fuel getting on it............

 

Thanks for the reply. I'm not sure if any fuel or not. I only meant no carbon build up and doesn't have the whitish look of having been hot.
New symptom I noticed today, it backfires while accelerating.

 

Does the mis-fire start at high rpm cold (4000 ish) and as the engine warms drop down to 3000 rpm range? Do you have what sounds like belt squeal that goes away as it warms and then returns at stops after traveling at highway speeds? These are some symptoms of a failing syncro (cam poistion sensor shaft), it is the remanents of the old distributor and is used to confirm spark and injection timing. However, the ECM does not monitor for fault codes over 2500 rpm. THe TSB test is to monitor EGR signal for cycling over 150 or 170 to its peak of 1050. I had a mis-fire show after installing new plugs and wires that no one could figure out until I got with a freind that had had a 3.0 Ranger with syncro issues. Syncro problems seem to vary with one exception sooner or later they seize, strip the gear and at that time oil pressure drops to zero. Like an old distributor the oil pump shaft is turned by the bottom of the syncro shaft.