Hello guys. I'm about to pull my hair out with this problem I've had with this truck. The kid at Orielly eventually got a code he said was either spark plugs or coil packs but would start with spark plugs. He said the code kept bouncing around where a couple of the cylinders weren't firing.Well the vehicle is a 2007 lincoln mark Lt engine 5.4 4wd basically a ford. Boy was I in for a treat with those spark plugs. got 6 out of 8 without breaking them so ended up buying the lisyle tool which worked well getting the 2 broken ones out. now he sold me autolite spark plugs instead of motorcraft is that an oops? because that didnt help but the engine light went off. so i bought coil packs and same thing. runs rough. my question is are the coil packs all the same or is there a number on them somewhere where they need to go to a certain cylinder. also on the passenger side have an exhaust manifold leak. it has a crack on the manifold. any help be really appreaciated.
brian

 

Coil packs are not cylinder specific, and Autolites are fine. Exhaust manifold leak/crack is common, had mine replaced at 30K.

What is the code your getting?

 

Dont use autolites ONLY use Ford motorcraft plugs in a Ford, and only use motorcraft COP and change the rubber boot also. Use dielectric grease on the boots also

 

Also when was the last time plugs were changed, cop boots replaced?

 

I replaced the coil packs and boots with original Ford parts. I also used diolectric on the new boots. The guy at the part store never did give me the actual code number only that the handheld machine he was using indicated that there was a couple cylinders that weren't firing and that I should start with the spark plugs then the coil packs. After putting the Autolite plugs in, the engine light inside the dash panel went off but still ran rough so I ordered new ford coil packs and boots and still running rough. So I'm stumped, do I spend another $ 100 on motorcraft spark plugs? instead of the Autolite ones the part store sold me.

 

Just about everyone here agrees the Motorcraft plugs are superior, but new Autolite plugs shouldn't cause a misfire unless they are defective, which is unlikely. I've also read that Champion makes a one piece spark plug for the 3-valve engines that won't break, I don't know anything about how they perform otherwise.

I would suggest another opinion from someone with more experience, using better diagnostic equipment. Did he clear the code and did it return right away? Did you get a Check Engine Light? You don't say how many miles you have on the truck which may be a clue to other readers. The Ford Service manual suggests using a test lead that installs between the coil and plug and lets you see if the coil is generating enough voltage to create and arc a clear plastic tube. They aren't too expensive, or maybe your O'Reily's has one....

Even though the ignition systems may be very similar, especially for a 5.4. your Lincoln is more similar to the F-150's than Super Duty trucks so check that forum and search the "Modular V8 (4.6L, 5.4L)" forum under "Performance, Engines and Troubleshooting," you might find something that would help there....

 

 

Not sure how many miles on your 5.4 or when the last time the plugs were changed - just be really sure you want to do this

 

As a general troubleshooting tip, if you have misfires from multiple cylinders, coil packs are usually not the cause. Same with spark plugs. I guess it can happen, but the chances of multiple coils or multiple plugs suddenly failing at once is pretty remote.

 

Out of all the 5.4's Ive had i have only had multiple coils go out at the same time once. I've had them go out a week or two after I changed one, but like you said, rarely at the same time.

 

They didn't clear the code . The engine has 171,000 miles without changing the spark plugs. They were the original spark plugs and needed changed. There was so much gap and not much of an eloctrode left. After I put in the spark plugs and started the engine, the engine light on the dash went out but still ran rough. They said without the engine light on, they can't rediagnose it.

 

The reason most 5.4 owners don't change the plugs is due to the picture I posted above. Do you know if they broke any plugs?

 

your pics didn't come through but I changed the plugs and only 2 of the plugs broke. but they did need replaced as the were in bad condition. I bought the lisysle tool and removed the 2 broken plugs with no problem except the cost of the tool. i don't understand why the misfire after replacing with new plugs and coil packs.

 

I would go to somewhere like harbor freight and buy a code reader, they're usually less that $100. I would look to see what codes are there, which cylinders are misfiring, Then I'd clear the codes swap your COPS with other cylinders and see if the misfires move.
If they do move, then more than likely you have bad boots or COPS.
If they don't then the new plugs could be bad. or you have bad signal to the COPS.
If everything is good, then you could start by swapping a couple of injectors around to see if it makes the misfire move, if it doesn't then you'd need to check the pulse signal going to the injectors.
If all that looks good but it's still misfiring, it could be mechanical, like an intake valve not closing all the way, after all it does have high miles on it so nothing is out of the question. Did you do any compression test when the plugs were out?
Good luck

 

You mentioned COPs. What are those? When the engine was running, I would take off one of the electrical connectors to the fuel injectors to see if I could hear a difference but I couldn't. I didn't do it to all of them just one.