Spark Plugs Causing Engine Jerk?

[metaldrgn]

In general, people tend to blame spark plugs for issues too often. Most problems usually come from cops or sensors. Plugs don't usually fail suddenly and start causing problems.

They do usually just start going bad one day or at least it seems that way. I've had multiple cars and that's what happened on more than one not to mention all the forums with this issue. I don't know why ford cops have such a high fail rate, but spark plugs should not be overlooked.

 

[My07EL]

Update as promised. Just changed the plugs at 90500. Stutter at cruising speeds went away. Used a makita cordless impact driver and 0 broke. I did have to break 7 of them free 1/4 turn with a ratchet but used the impact before and after.

 

[valenrandy]

If you dont mind me asking, which plugs did you replace them with? I'm currently looking to replace mine with MC SP515 or the MC SP509. Just trying to figure out the best/proper/correct ones to use.

Thanks

 

[metaldrgn]

Nice! Thanks for the update and I'm glad it's working good again.

 

[My07EL]

They were the 515's

 

[FireTractor]

Thank you for all the replies. I had the plugs changed yesterday, and none broke! They also found a bad coil, so the problem seems to have been resolved.

 

[wadesdad]

Congratulations! Happy motoring Kyle. I don't think the COPS or plugs are a "problem" if you consider how often we used to have to change wires and plugs. You got your plugs at the right time. COPS turn south at 120k plus miles and are EASY to install.

 

[Barjrob1972]

2007 Expy EL EB. Mine had the same problem. At lower rpm's it felt like the truck was missing when I gave it gas and then on a long trip, I went to pass and it starting missing at higher rpm speeds.
A plug change fixed my issues, too.
Factory plugs at 108k miles.

 

[Nightsun]

Had this same issue with jerking/hesitation. Dealer told me all COPS were bad except for #5. They changed these out on warranty. They suggested replacing the plugs too but at $400 bucks I am going to do it myself this weekend using an impact and some pb blaster. Anyhow, the jerking issues went away completely by just replacing the cops. My 07 5.4 has 128k miles on it now. Need to research to see what plugs are best to replace the stockers with.

 

[toms89]

In general, people tend to blame spark plugs for issues too often. Most problems usually come from cops or sensors. Plugs don't usually fail suddenly and start causing problems.

I realize this thread has just be revived but....

I believe the opposite to be true. With the internet and forums like these people tend to blame the cops first when plugs are a wear item, the gap grows over time and they can and will misfire or foul. In fact as the gap grows it puts more load on the cop and increases its chances for failure. The spark is always looking for the path of least resistance. Whether its across the plug gap, through insulator to ground or coil to ground. The higher the load on the motor the higher the resistance to fire across the gap as well. That's why boosted vehicles use much smaller plug gaps.


I personally have never had a cop fail yet. Spark plugs yes...

What's interesting to me is I rarely see cop failures mentioned on lightning forums. Sparks plugs all the time. But then they push the motors much harder but at the same time run significantly smaller gaps decreasing the likely hood of misfire and the demand on the cops.