Help with misfires!

[mj.heil]

Hey all,

Long time lurker first time poster. This forum has saved my butt so many times so hopefully it can now! To start I drive a 2010 sho non pp with 105k miles. Stock except for drilled rotors.

So I am experiencing a nasty misfire. It's always there on the highway if I try to accelerate, no codes usually. It's RPM related not speed related. Today right on start up the rpms surged at idle, low power, and flashing CEL. When I got to work (short drive) it smelled of unburnt gas. After work it took a long time of cranking to start. Then ran fine.

Codes are misfires on cylinders 4, 5, and 6. As well as a random misfire.

A few weeks ago it threw a code for o2 sensor bank 2 downstream. I replaced all 4 sensors and it got better for a short time now it's back. The code for O2 sensor has not returned.

I'm starting to really worry because now I know it's a misfire across a whole bank of cylinders.

Any help would be greatly appreciated!

 

[luigisho]

How old are the plugs and coils? I would start there. You can swap things around to see if the misfire follows. This might also be true of O2 sensors. A whole bank misfiring could be a few things. Bad O2 and a clogged cat comes to mind first, but this is not the sort of part you want to throw at it. Start with ignition and go from there. If you suspect a converter is bad you need to find a shop that can test it and won't declare it bad just because they want to sell you one.

 

[yaycandy]

A whole bank misfiring sorta makes it easier. I think i had those codes on my old engine from an acting up vvt solenoid, under the valve cover. Probably from oil gunkin it up. Could be anything down to the o2 sensor. Ford dealer could probably find and fix the problem quicker and possibly more expensiver. But quicker is better

 

[RoketRdr]

To add to what's already been stated...also check the connector that feeds power to all the coils. May just need to be reseated or cleaned.

 

[FiveLeeter918]

Pay $100 for the Ford diagnostic and see what it comes back with haha

 

[luigisho]

Pay $100 for the Ford diagnostic and see what it comes back with haha

I actually really like this idea with modern cars. If you can short cut diagnostic time and determine the best course of action, I would advocate for that after the easy stuff is off the table.

 

[mj.heil]

Thanks to everyone for the input, to start I did bite the bullet and took it to a very reputable local shop for a diagnostic service. Local ford dealer was booked through the weekend. I will post with what they say.

As for the plugs they are maybe 2 years old 30k miles. O2 sensors are all brand new so unless I got a junk one...

The vvt solenoid is actually something that came to my mind as well. I do have timing chain rattle on startup as well so there may be more to that theory.

 

[luigisho]

I would check plugs that are easy to access after 2 yrs on a boosted motor. Also I would swap ignition coils to seperate bank and see if the miss follows the coils. same for O2's if they are easy. If the miss moves to other cylinder(s) then you have your issue, if not then move to the next suspect. Eliminate the easy stuff before buying parts (coil move, inspect plug and plug gaps etc.)