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Hello all. I am currently trying to solve an ongoing issue with my 2006 F-150 that has 200,000 miles on it. When I purchased the truck, it ran and drove great until I started having the misfires under load issue. Long story short I replaced all 8 coils, and put a set of 8 brand new spark plugs in at the same time (at the time of this posting both the new plugs and coils have less than 5,000 miles on them). I used MotorCraft OEM plugs and coils, and did not have any issues with them breaking when I did the work myself. For awhile the truck has been fine, until recently. I should also note I replaced both cats on the truck last year as well. If what I was told when I bought the truck was true, then the fuel filter has maybe 10,000 miles on it at this point.
The other day I was cruising at about 50mph when I lost all acceleration in the engine and experienced a very heavy degree of misfire, that's when the check engine light started flashing. The misfire, as well as the flashing engine light continued on for quite some time until I could find a place to pull over. When I stopped the engine light went off, and likely I had an obd scanner laying in the car and I pulled a pending cylinder 7 misfire code. What confused me was that I've never seen a flashing CEL on this truck, only a solid light. After some Googling I gave up on the try and solve it myself method, and took it to Ford. $150 diag fee later, they claimed it was loose spark plugs, tightened them up, sent me on my way. I will admit, it did run better, and the engine sounded better at idle.
Two weeks later, the issue is back. Same deal, driving at about 45mph, extreme misfire comes out of no where, blinking CEL, same cylinder 7 misfire code. The only difference this time is that I can notice that engine is not running right in any case, it's idling in a not normal rhythm, and just the way the engine sounds in general is not normal. Any speed I drive at the thing is skipping a beat, even just cruising. I should also note upon starting up, there is quite a lot of ticking sometimes that lasts a few seconds then goes away.
Anyone have any ideas about what could be causing this issue, suggestions or things I should try?
A flashing CEL is a indication of a mis-fire condition.. change #7 plug and proper torque..if you bought and replace COPs they most likely came with new boots and springs.. was dielectric grease applied properly to the boot ends ? This prevents moisture intrusion.. if replacement of #7 plug don’t work try swapping COPs with another cylinder and see if DTC follows.. the #7 plug may have gotten cracked during installation. If none of that works to clear the DTC then I would look at the #7 injector.
There have been enough guys here finding defective Motorcraft spark plugs 'out of the box' for us to start recommending "Buy 10 to make sure you get 8 good ones". I'll bet @techrep is right - but the OP may not have cracked it during installation.
I did use grease on the plugs, and did use new boots and springs as they were included.
I changed out the #7 coil, and even put on a new plug light is off - no pending codes either. However, still a decent amount misfire and now a pretty loud rattle has formed (not talking about the usual 5.4 ticking, talking about a real rattle, and it doesn't sound good normal).
I think the injector will be my next move. Out of curiosity, this plug has less than 5,000 miles on it. Should it look like this for that low of mileage on it? The last round of these I replaced (if I remember correctly) didn't look this bad.
To me --- there is evidence that plug was NOT torqued properly and exhaust gasses were escaping the threads. That opinion is based upon the evidence of exhaust carbon deposits on the white ceramic just below your thumb. That isn't the cause, but aggravates carbon deposits on the extended plug electrode. The platinum tip looks fine.
10-08-2017, 03:20 PM
Misfire and blinking CEL
