At 100,000 miles I had the spark plugs changed in my 2006 F150 . I did not at the time replace the coils. Shortly after that I had a cylinder misfiring, the plug had failed. I replaced the plug and used the opportunity to replace all coils. Within 5,000 miles I had another, different cylinder misfiring. I pulled the plug and found it to be heavily corroded. I replaced that plug. Now, again, I had another cylinder misfiring and that plug had also failed. I asked the local mechanic if there was ANYTHING I could do to prevent this from happening again. He said he knew of no solution and that the engine has a poorly designed ignition system that is prone to failures. He said that even if I replaced the engine he could not guarantee this would not happen again. I asked if he would replace or rebuild the heads and he refused to believe this would make any difference.

What can can be causing this problem? Why did it start after replacement of spark plugs and never happened before? I am willing to do whatever is necessary to make this a reliable vehicle again.

I am new to this forum and apologize if this has been covered before. I greatly appreciate any help.

Thank you

 

I am new to the forum, but I do know that the engine is 5.4l. Typo in my post...

 

What brand of spark plug are you using? Can you post a pic of one of the damaged spark plug?

 

Thank you for the response. I don't have the vehicle or plug with me and won't for the next 3 days. When I do, I will send a photo of the plug. I think the plug is an Autolite, but not sure.

 

In short....no, so very wrong, it is a very reliable and high discharge capacity system 1st used by porsche dating back to the 80's (IIRR).....

Run MC plugs & COPS (if you're not- as that is typically the issue) and you should be fine.

 

Thanks for the response. I am not sure who made the coils that I bought. The problem happened both before and after the coils were replaced. Can I somehow test the coils to see if the new ones are up to spec and also test the original ones that I removed. I could then decide to either keep the new coils in place or exchange them out for the originals. It sounds like if I replace all plugs with Motocraft plugs and test the coils, I should have this fixed....

 

As requested, I am including photos of the most recent spark plug to fail. It is a Motocraft plug.

 

And, these are the coils that I used after the first spark plug failure and I had the bright idea to change out the coils when I replaced that plug.

Part #: WREPF504614ATP

AUTOTRUST PLATINUM COIL IGNITION COILS

AUTOTRUST PLATINUM products are guaranteed to meet the original manufacturer's standards and quality;
Backed by a 5-year unlimited warranty; If the part breaks or is damaged anytime with Ignition Coil F-150
AutoTrust Platinum

 

Your right as far the mis-fire goes.....from what I see in the pic (and it can be deceiving), there appears to be a "ring" at the shoulder of the plug indicating a leak or where combustion gases slipped by.......also looking at the plug in general, the burn residual pattern is very unusual......ie, something is not right. I'm wondering if (and this is a swag)...

1. the shoulder where the plug meets the cylinder head is not fully flush creating a sealing issue

2. Because of the previous ignition miss, there is excessive carbon buildup on the valves creating combustion chamber issues, detonation, etc.

 

That right there is detonation . Might be something wrong with your timing components.

 

What should I do to check timing components?

 

Well, detonation typically leaves arc welder type burn marks/deposits on the electrodes...I don't see any of that....but improper fuel delivery would create "unique" burn patterns that you see as well.....meaning possible a bad/clogged injector or a bad COP

 

Thats what happened with my avatar when I had detonation, you are right thou, most likely a COP having a weak spark or a bad connection on the injector or COP.

 

Thank you all for our input and suggestions. I have not yet replaced all spark plugs and coils. In the meantime, the engine has again started misfiring. It has been "hesitating when under load and then runs better with overdrive turned off. Now it started hesitating under low load situations and the check engine light came on and stayed on (always on, not blinking). Then after resting the engine, the check engine light was off and the engine was running well. I used my OBC reader when there was no activated check engine light and there was a stored code that said "misfire cylinder #4". That is the same cylinder that just got a brand new coil and spark plug by a local mechanic. So, after replacing the coil and plug, the engine continues to misfire on that cylinder.

Cylinder #4 is the most difficult spark plug to access and do not want to pull that plug and see what is going on.

What I am looking for is a suggestion on what I should tell my mechanic to do to fix this and make it never happen again. I am not looking to do the bare minimum. I am willing to invest real money into fixing this instead of buying a new vehicle.

I have heard it could be fuel mixture. How can I check and fix that?
It could be related to COPs and plugs. I know I can replace them, but that was done on a cylinder that is now failing again......
Could it be timing or valve related?

I keep thinking that I should just replace the heads and be done with this....

 

it is possible to get a bad part do not over think this. remember the kiss method keep it stupid simple.
do not jump to replacing the head start simple and cheap and go from there