misfire codes need help '05 FX4
 

i was pulling my camper and the check engine light started flashing so i stopped and shut down the vehicle. it only did it when the OD was off. it was fine while the OD was on. so i got the codes read and they were misfires on cylinder 3,5,6. now i have a high pitched sound coming from the engine on acceleration. Anyone able to share some wisdom on this i'm sure this is common. thanks

Mileage ? and when was the last tune-up ??

Mileage is 169000 and I changed plugs at 158000. Also fuel filter and FPDM. I'm going to change the coil packs today. Oh ha I've done the O2 sensors too. O2 sensors were done within the last 3 months.

ok i changed my coil packs and all but one of the misfire codes are gone and now i have a code for bad downstream O2 sensor bank 1 P0171 and oil temperature sensor code P1184 and a P0420 code which is a clogged cat bank 1. I chnaged the spark plug cylinder 5 and am waiting for the new O2 sensor so i can replace it with a motorcraft i had put a bosch in there. hopefully it will be the problem. any suggestions would be great. I used a scanner to see if the cat was bad but it didn't say it was. going to to a temperature test this week.

The "high pitched" sound may be an air leak (vacuum?). Check any and all lines that run to the air intake for cracks or unplugged. This could be causing a lean condition (unmetered air), and a possibility for the codes too.

im having the same issue: code p0420.engine light came on/off all week.unsure what the actual cause is.when you find out for certain please post it.you and i may have the same problem.im still in the process of narrowing it down.

oh,high pitch sound prob vacuum leak or water pump going out? just a experiential guess