MHuston05

A new code recently came up on my 2005 f150 5.4 4x4, I have a bully dog programmer that reads the code as cylinder 7 misfire. I deffinitely think this is the issue because at times my truck will sputter, i have aftermarket exhaust and you can hear it plain as day. It doesnt do it constantly while driving tho, for example at and idle it runs fine and at low speeds fine, but when you try to accelerate quickly or at higher speeds it is very evident. Any ideas what may be causing this or any similar issues?

Prof

How long has it been since you changed out your COPS and plugs?

If you haven't that is your culprit. Happened the same way on mine, and when the COP fails, it is rather catastrophic - your truck will feel like something is really really wrong. Right now it sounds like it is telling you that failure is imminent - prepare to change that COP and plug out right away to avoid nasty limp mode, flashing engine light and rescue on the side of the road.

Search forum for plug and cop changing and you will read more than you ever wanted to know...

While you are in there, change them all out if you haven't, my experience, once one goes they start falling in rapid succession. YMMV.

MHuston05

I havent changed those out before. thanks so much ill try this and get back to you. any advice as to which brand of COPs and Plugs to go with?

Prof

Well, now this is a whole other question. Many (respected) folks here say, don't cheap on COPS, they will only let you down, go Motorcraft...but those COPS are 50-75 per x 8 cylinders, you get the picture. Others swear by the super cheap cops you can get on Amazon for like $70 bucks for the set of 8. I have a mid range but cheapo set, and apart from a single wandering misfire (no codes), that travels from one cylinder to the next and hasn't effected the engine at all that I can tell, they have worked well. Some folks love/hate the yellow Accel COPS...get on Amazon, plug in make and model and read the reviews.

Plugs, stay with new Motorcraft, 515's.

Now, this is a job you can do yourself. But, it is a PIA x2, no x3. Problem is, you take it to dealer, they will charge you through the hole to do it. Crazy.

If those plugs have never been changed, they are way over due IMHO, the myth of 100k plugs is BS. But you gotta read the threads on getting them out, it is involved, lengthy and fraught with danger...but definitely doable with patience and the right tools. Hell I am a teacher and I did it in my garage in the suburbs, very little prior wrench experience (but solid mechanical aptitude), I was patient, followed the instructions and had zero plug breakage (yes, that happens frequently I am told). Research is the key, YouTube videos are critical...go search this forum and YouTube for plug change, and you will see it...

Good luck!

yelbike

Previous post is exactly correct!
I bought OEM cops and 515s x16 for $300 off eBay. Did both my wife's '07 expy ( broke 2, no biggie) and my '07 mark Lt.