had this flashing light yesterday for the first time in my ownership of just over a year...2007 S'Crew with 125K miles and the usual wounded 5.4 3V...

yesterday enroute to gas station I opened it up on the highway and received a flashing check engine light...using a buddy's scanner I got the P0302 code...#2 cylinder misfire

I had no gasoline smell
No backfire
No stuttering, stalling or drivability issues noted
the code cleared itself after getting off the gas but returned when I gave it the gas on the way home from the gas station
it has never shown the flashing engine light in the 6K miles/year plus of my ownership

from what I've read here and elsewhere I have planned to check the COPs, boots, springs, spark plugs etc. one at a time but if you have any advice I'm all ears...

I am not a mechanic and it has been a long time since I've worked on my own vehicle other than the easy filter changes, cleaning throttle body, intake and such...

I took over this vehicle at 119K miles from original owner and have spotty records on repairs...the plugs were changed less than 2 years ago and 20K miles but it is unknown if the dealership changed the boots and springs...the FPDM was replaced about 18K miles and 18 months ago...

any insight is appreciated...this is not my daily driver but I've done quite a bit to it to keep it from the scrap yard where it was headed in January 2019...

Thanks

Bill

 

when I get some time to look into this, my first intention is to swap the #2 COP with another to see if the misfire follows...I can inspect the condition of that COP too to see if it appears to have ever been replaced (if they would do that as a matter of course during a spark plug replacement at a dealership)...and hopefully I can inspect to see what plugs were put in by the dealership in mid 2018 as I believe they should have been the newest SP546

Bill

 

stop driving it if it gives you a flashing CEL..that means that you could do serious damage

 

Sounds like an ignition coil is failing

 

Id do your plan of swapping a coil (note: condition of boots, cleanliness of springs, and whether there is corrosion at spring/coil contact point).

If that doesn’t reveal issue, move on to swapping two plugs.

If still not revealed I’d then swap two injectors.

You could do two or all three of these swaps at the same time (to different cylinders) and/or guess and replace with new parts before id’ing culprit. But I’m a fan of trying to limit the changing of variables while diagnosing (and not spend money on parts until problem known). You probably know all of this - but maybe I’ll help somebody.

Fwiw, I replaced all my plugs as maint, then within about a year I was chasing a misfire one one cylinder). Didn’t think there was any way it’d be a plug, but it did prove to be a plug (I just replaced that one plug). ( The problem plug would only misfire under load.... but it’d idle all day and/or drive around low speed all day without misfiring).

 

Could be a fluke -if light goes off then you're all good to go!
Could have just been random and threw a code.

 

thanks for the feedback...when I realized what the flashing check engine light meant, I stopped driving it but the light went out which made me think it was no longer having the issue for which the flashing light was alerting me to...

further...the flashing light was only flashing when I was merging onto a 55 MPH zone and had the accelerator to the floor...it stopped soon after getting off the gas...

laterongc...I plan to try one at a time diagnostics because I don't need to drive the truck (not a daily driver) and I don't want to kill the truck...It may be awhile for me to get to this because of weather and my lack of mechanic skills but I'm willing to give it a try...

thanks for the help and anyone who still wants to pipe in with ideas, encouragement or critique is welcome to share...

Bill

 

so I had some time to look into this a bit more yesterday...and I hope not to jinx it but it seems to be solved/fixed...

after removing the connecting bolt I noticed there was very little tension where the boot connects to the spark plug (internal spring?)...I removed the #2 COP and inspected the boot, COP and spring...noted there was what appeared to be clean dielectric grease where the spring meets the spark plug...everything else, while dirty on the exterior appeared normal...

I reattached everything and took it for a test drive...at first all seemed fine but then under extended load while on the highway, there was the flashing Check Engine again...

once at home I looked locally for a replacement boot and spring to see if that might clear up the miss in #2...I located one at O'Reilly auto parts and went to pick it up...after viewing in person, I saw that Motorcraft does not supply the spring and O'Reilly Auto Parts did not carry that part separately...the man behind the counter did tell me that their Ultima Select version had the needed spring and after some thought ($5.49-Lifetime Warranty) I thought I could at least see if this clears up the issue before moving on if it did not so I bought it...

removed the OE COP...cleaned the exterior noting that all connections looked clean and unburned with no residue from dielectric grease or anything...installed the new boot and spring with dielectric grease at the connections and reinstalled...

although raining out, I took the truck on the highway run again and had several opportunities to put the engine under load, passing gear, etc...no flashing Check Engine light...

I had cleared the codes prior to the last run with the new boot and spring and upon my return and rescan, there was no #2 miss...I realize this doesn't mean I solved the problem until I can log some more miles but it looks to me like I may have this solved...I'd like to change out the boots and springs on the other cylinders and may make a Rock Auto order soon to get these...

For those looking, Motorcraft parts, at least the single I had in my hand didn't have the spring in the sealed pouch...I had read earlier that the AC Delco or Denso versions might be the same maker and DID include the springs but these were needed to be ordered from O'Reilly Auto Parts so I went with their house brand despite thinking they might not be the best choice...the one I did buy appeared to be the same as what I removed...

Good luck with your truck and thanks for the help everyone

Bill

 

on the fence over changing the other boots or leaving them alone as the truck seems to be running just fine...seems to be a nice little project to take on as it is much less than $50 to do all 8 (7 more for me since one is already new) and the wires appear not to have been changed with the plugs when original owner had it done 20K miles ago...

Bill

 

I know it has been a while but did that solve your issue? I am running into the same issue with my 2013