Random misfire 2011-2014 Coyote - check this section of engine wiring harness

[stevbd]

I haven't seen a post on this: If you have random misfire problems, carefully check the engine wiring harness in the area of the lower right-hand front corner of the passenger side valve cover. On my 2011, there is a gray plastic fastener which attaches the harness to a metal tab on the bracket that holds the ECU, and then the next fastener is a xmas tree type push pin which goes into a cavity in the timing chain cover. There's no heat tape or other protection for the harness in this area and taken together, these two fasteners pull the harness up tight against the corner of the metal timing chain cover, sort of underneath the valve cover. On my car, about an inch of the black plastic sheath on the harness was completely worn away and three of the wires inside were worn through down to the metal wires.

Hope this might be helpful to someone.

 

[KazarS197]

I haven't seen a post on this: If you have random misfire problems, carefully check the engine wiring harness in the area of the lower right-hand front corner of the passenger side valve cover. On my 2011, there is a gray plastic fastener which attaches the harness to a metal tab on the right fender, and then the next fastener is a xmas tree type push pin which goes into a cavity in the timing chain cover. There's no heat tape or other protection for the harness in this area and taken together, these two fasteners pull the harness up tight against the corner of the metal timing chain cover, sort of underneath the valve cover. On my car, about an inch of the black plastic sheath on the harness was completely worn away and three of the wires inside were worn through down to the metal wires.

Hope this might be helpful to someone.

Great tip! Do you have a photo? I just proactively looked at my 2012 and can't see much from the top.

 

[stevbd]

Great tip! Do you have a photo? I just proactively looked at my 2012 and can't see much from the top.

This is the section that was rubbing against the timing chain cover, which is the curved metal piece in this pic. It wasn’t visible until I pulled the harness away and inspected it.

 

[KazarS197]

Stop at your local AutoZone or other car parts place and see what kind of hose cutoffs/ scraps they have sitting around. A couple years ago I picked up a whole box for something like 5 bucks. They guy said he couldn't just give away even though they will be thrown out so I told him charge me 5 bucks. Those 4-8 inch lengths come in handy for protecting stuff like that. Split ,zip tie and tape.

 

[stevbd]

Stop at your local AutoZone or other car parts place and see what kind of hose cutoffs/ scraps they have sitting around. A couple years ago I picked up a whole box for something like 5 bucks. They guy said he couldn't just give away even though they will be thrown out so I told him charge me 5 bucks. Those 4-8 inch lengths come in handy for protecting stuff like that. Split ,zip tie and tape.

Yeah it'd be so easy to protect it, I'm just annoyed I never found it until now. The harness looked okay to me but obviously I didn't inspect it carefully enough. I was more focused on loose or bad connections and wasn't thinking about chafing. I spent a bunch of time replacing connectors to the coil packs as well as throwing a whole bunch of other new parts at the car. I'm now in the process of installing a new engine harness and I will protect that area carefully.

I guess it's impossible to know but I am kind of wondering how many reports of a new harness fixing the random misfire problem are a result of this small but super annoying design defect. The grey connector positions the harness snug up against the corner of the engine and ensures chafing.

 

[KazarS197]

You found something that is extremely valuable info for others here that could save us loads of time and cash! There's quite a few threads that solved unsolvable issues on here. I definitely appreciate the thread. Gonna look at mine a bit closer. I know those found simple little things are life savers. I had an 04 Jeep Grand Cherokee that lost the front vents and stayed on defrost. I pulled everything apart and nothing wrong anywhere. A little searching and found a jeep forum post that lead me in the direction of a vacuum line under the battery. $2 piece of hose, a 1/2 hour and fixed. Who in their right mind is going to look under a battery for a climate control problem. I bet if I took to a repaired shop the would have started replacing everything, not been fixed costing a grand.... I keep throwing a code for O2 sensors and found an extension on the driver's side because of the long tubes. Removed it and repositioned the back harness for just enough length to connect without and fixed.

 

[stevbd]

@KazarS197 thanks for the kind words and encouragement. I will be very happy if this helps someone else. I also will be happy if it finally fixes this f*&%&*$ random misfire issue. I have loved this car and honestly it owes me nothing but this random misfire thing has been making me want to set it on fire lately.

EDIT - Another question just came to me, could the positioning of the engine harness and location of this chafing and shorting be related to all the reports of fuel starvation in left hand corners? Does the engine maybe shift a little to the right and short out the damaged harness in left hand corners, while shifting to the left and pulling away from the damaged harness in right hand corners so no misfires? The usual explanation has been fuel sloshing to the right side of the saddle tank and away from the pump in left hand corners, but people report these problems even with a mostly filled gas tank and 200tw tires which doesn't really make sense.

 

[KazarS197]

@KazarS197 thanks for the kind words and encouragement. I will be very happy if this helps someone else. I also will be happy if it finally fixes this f*&%&*$ random misfire issue. I have loved this car and honestly it owes me nothing but this random misfire thing has been making me want to set it on fire lately.

EDIT - Another question just came to me, could the positioning of the engine harness and location of this chafing and shorting be related to all the reports of fuel starvation in left hand corners? Does the engine maybe shift a little to the right and short out the damaged harness in left hand corners, while shifting to the left and pulling away from the damaged harness in right hand corners so no misfires? The usual explanation has been fuel sloshing to the right side of the saddle tank and away from the pump in left hand corners, but people report these problems even with a mostly filled gas tank and 200tw tires which doesn't really make sense.

You might be on to something. Now trace all of those bare wires and their functions . That gave me anxiety just thinking about it. . Ya that's not happening....

You've been here for a while. When you doing a vehicle profile and build thread?

I just remembered your other thread. If you find out that you found your misfire issue. Copy paste this thread to a reply in your initial one. That way both are linked together.

https://trackmustangsonline.com/threads/chasing-random-misfire-seeking-ford-performance-engine-harness.20814/

 

[stevbd]

Fair point, I've never done a profile I guess I'm kind of a slacker TMO-er. I will do one eventually but there's not a lot there.

I had the same thought process as you, by the way, "I wonder where these wires go" followed by, "nah."