My 3.0 Ranger misfires about 20 seconds after startup, and continues to misfire. We installed new plugs and a coil pack. After initial startup, you can verify spark on all 6 cylinders with a timing light. After about 20 seconds cylinders drop out, such as 2 and 6. Sometimes 1 will drop out as well. Anyone experienced this?

Like i said before there is no evidence of a miss right after startup, it is only about 20 seconds into the run time that it happens.

 

I'm interested in wondering what the problem is cause my truck does the same thing. Sometimes it also does it at about 3,000 rpms but will clear out whenever my motor gets at normal opporating temperature.

 

if it is run with a coil pack its bad. the controle moduel is biult into these and thats the only other thing that could drop spark

 

The syncro can also cause this problem particularly over 3000 rpms as the ECM does not register fault codes on cam sensor over 2500 Rpm. The syncro will also tend to give you a whine that sounds like a belt slipping when it is cold.