05 sports trac SOHC flex fuel, random misfires, misfire 1,2,3, etc

[Larry J Brown]

05 Explorer sports trac SOHC flex 4.0

Issue:

Parked it one evening and next morning went to start, thought I heard a small clunk or something, not sure now if i even heard anything lol. but engine light came on and truck ran very rough. Didnt drive it.

Code says random misfire, misfire in cylinder 1,2 and 3, 02 sensor bank 1, sensor 1 stuck burning rich.

My wrencher buddy and I changed out Coil pack, Wires and plugs. Re-set codes and truck ran smooth idled for 2 cigs. lol. Thought all was good and went to drive truck home (roughly 2 miles)about a mle in the light came back on and truck started running rougher like misfiring then it lost all acceleration, truck stayed running and if gas was pressed it felt as it wanted to go but couldn't (bogging). after about 10 or so seconds the speed picked right up as if nothing happened and was good for a few hundred feet then it would do same thing (Bogging).

Code reading showed all the same codes as 1st time. We thought maybe it was the no gap Bosch plugs so we replaced with some that we gaped (54-56), reset codes and let run again for roughly 20 minutes idled. Drove truck for about 5 miles, flat road and couple small hills and thought all was fine again but on the way home all the same symptoms came back.

I'm currently at lost on what to do next with budget in mind. I've had a few folks say timing chain, timing chain tension bolts, loose wires (all checked), all (3) 1,2,3 fuel injectors all went bad at same time ?

So any help here would be greatly appreciated.

 

[boominXplorer]

Take out the bosch plugs and install autolite double platinums, should fix the random misfire.

 

[Larry J Brown]

Take out the bosch plugs and install autolite double platinums, should fix the random misfire.

Thanks for the response. Those were the exact plugs we exchanged for the Bosch ones. Same result.

 

[boominXplorer]

Are you sure its an intermittent issue? If it runs smooth some times and some times falls on its face then its probably not timing chain related. I would be looking at the coil pack wiring to pcm and or the pcm.

 

[Trackerforsport]

It could be a clogged cat..just had the same issue min was a wire and coil pack....did you put any dielectric grease on the wires ?

 

[Larry J Brown]

Are you sure its an intermittent issue? If it runs smooth some times and some times falls on its face then its probably not timing chain related. I would be looking at the coil pack wiring to pcm and or the pcm.

It runs smooth at cold start up and after codes have been cleared, then the intermittent starts when it warms up. I'll check the wire to pcm and what s involved to checking the pcm ?

 

[Larry J Brown]

It could be a clogged cat..just had the same issue min was a wire and coil pack....did you put any dielectric grease on the wires ?

My wrench buddy put on some grease, I cant say for sure its that grease but would assume it is.Would the Cat glow red f its bad and would it show the codes that given if it was a cat issue?