[Expy2017]

I have a 2017 Expedition 3.5 Ecoboost with 94k miles and I’m having an unusual issue I’m hoping someone might be familiar with.

Plugs and coils were changed about 3500 miles ago and the truck was running butter smooth. I used motorcraft plugs and Napa in house brand coils (Echlin).

This past weekend the truck threw a CEL and wife said “it didn’t want to go.” Went to pick her up and it was idling fine but due to her description of what sounded like a trans issue I ended up having it towed. It was a misfire on cylinder 6 causing a bad mis. Coil was moved to cylinder 1 by the mechanic and the misfire moved it with, easy enough diagnoses for a bad coil. Coil was replaced free by Napa and changed. CEL gone.

Now the idle is no longer butter smooth. It seems to “tick” up and down about 50-100 rpm both cold and warm. The tach shows a sudden movement and the idle feels rougher than it was for sure although I don’t know if I would classify it as really rough yet.

Second issue is the truck feels slightly down on power. Not jarring but noticeable.

Any idea what to look for before throwing more ignition parts in the mix? Obviously I need to pull codes again but I don’t have a CEL and the truck seems drivable but something is clearly off. I am wondering if a vacuum leak is a possibility. I visually checked the hoses I can see but I don’t see anything clearly off. Thinking of idling the truck and spraying some carb or brake cleaner in there to see if it bogs down. Any ideas? Help greatly appreciated.

 

[Justinjs]

Well, I'll be the first... Use only genuine motorcraft parts, aftermarket stuff is sketchy at best, especially electronics. I went through 3 or 4 CV axles (car quest gold w/lifetime warranty), before I got a refund and spent 3x as much for motorcraft ones. The car quest ones would click right out of the box, sand in castings or idk... complete garbage though. Aftermarket t stat, also junk.

Spraying any cleaner is not advised at all in these engines.. seafoam, carb cleaner, ect. Something about heating up the turbos and cooking the bearings, could be an old wives tail though.

Do you still have the old coils?

 

[snakebitten]

I'll second the motion.
The 3.5 Ecoboost doesn't like aftermarket coils. I'm no expert and can't tell you why, but someone who has a ton of credibility (Ford Techmacoloco) makes an argument that the OEM coil is unmatched by the aftermarket.

 

[Expy2017]

Good thought on the old coils. Unfortunately they were badly stuck/seized to the plugs. The darn things literally would not come off with out crumbling like crazy and sticking to the plugs.

Napa is going to take the echlins back under warranty so at least they stand by their stuff. He mentioned they have the Denso coils which are listed in their system as OE.

Does Denso make the Motorcraft coils for Ford? At this point I’m skeptical enough to give it a second thought.

 

[Justinjs]

That I don't know. Someone else might have that info. Worth a shot to try it, just return it if it doesn't work.

Everyone hates paying for OEM prices, but they just work. For some odd reason, every aftermarket part I've put on has failed or fit poorly.

 

[Expy2017]

Well rockauto currently has these for $57 which is $2 more than the chepos I bought from Napa. I need to double check but this should be the part I need.

Im going to order these and attempt a return of the Napa ones. I’ll update the thread if there is an improvement to hopefully help others avoid the issue.

 

[Dghal]

I would agree. Not sure who makes the Motocraft coil but ford uses it for a reason.