- Ive got a 2016 F150 3.5 Ecoboost. Bought used from dealership. 124000 km on it now. In the last few months ive changed the spark plugs 3 times. Last change was last month and my engine ran fine, no misfires. But now its doing what it used to do. Misfires when i accelerate fast. I really have no clue what else to do about. The boots and coils are fine, and the spark plugs are a month old. Any suggestions? It doesn't idle rough. It just struggles to fire when I accelerate fast
Hook up a scanner, Mode 6 data, cylinder misfire counter, and you'll see which cylinder is acting up.
Then it's just the normal drill. Pull that spark plug, put on your reading glasses, and inspect its condition. Look at the electrode, the gap. Make sure it's clean. Check for carbon tracking on the insulator. Do the same with the coil boot.
If everything looks good, put that same plug back in but swap the coil with one of the good cylinders.
Then take it for a drive and check the misfire counter again. If the misfires move to the cylinder that you swapped coils with, replace that coil. If it stays on the same cylinder, replace the spark plug.
You have to use OEM plugs and coils on that engine.
My friends and old Ford tech. He just installed the Ford Motorcraft spark plugs in there and he inspected the boots and coil are good. It's misfires 3 times in the past few months and everytime I just swapped all spark plugs. I don't know much about engines but I am now assuming maybe it's carbon build up that's wearing them out? I'm running some injector cleaner in my fuel and I ordered a oil catch can. You think it's worth looking into getting a professional engine carbon clean from a shop?
Understand that coils aren't always Good or Bad. Sometimes one will sporadically act up. Especially when under load
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Same goes for spark plugs. (that's why these issues take a little extra effort to nail down)
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Check the misfire counters and at least narrow the problem down to an individual cylinder
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Your friend, when he was a Ford Tech, probably used a Power Balance test during a test drive which is a much better way than looking at the misfire counters but I doubt he took the Ford Dealer Scanner home with him when he retired. So the Mode 6 misfire counters will be good enough
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Here's what I think may be happening here. You have an intermittent misfire in one cylinder and the computer is tolerating it
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But when you mash down on the accelerator, that misfire isn't intermittent anymore. It's frequent enough for the computer to shutdown the fuel injector to that cylinder to protect the catalytic converter.
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Now you're trying to accelerate with 1 completely dead cylinder and that severely affects driveability
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When you let up off the accelerator, the parameters change, and the computer returns to providing fuel to that cylinder
Yeah that does make a lot of sense and summarizes what I've been experiencing. Gonna go get it scanned in next few days and I'll try and swap the coil with a different cylinder and go from there. Thanks! Appreciate it!
When did last change the fuel filter? Any codes?
I haven't changed it. I was just doing research on it all I'll look into replacing it. I just ordered a oil catch can too because I read the ecoboosts are notorious for carbon build up in the engine. But I'll definitely look into replacing fuel filter
Sometimes the check engine light will flash for a while and then go off. And sometimes it'll just stay on. Right now it's staying on. Haven't had time to go get the code read but in the past 3 times it's always been a random cylinder