Changed Spark Plugs.Then, "Check Engine" light appears and rough idle

[Atlanta Ford Fiesta 2018]

1) Changed/Replaced Sparks to Motorcraft SP-525's (Ford OEM approved brand pre-gapped)
2) Did not lubricate sparks plugs
3) Replaced one at a time, and wires are in-order.
4) After initial trouble, I put the original spark plugs back in.
As a result, I still have a check engine light on, but better idle and acceleration.

Autozone checked System, and plugs and coils were the results. Do damage to coils. No extra-tightening. The cover to my wire casing popped-of.lol! I do not know why that was so easy to just separate.

Putting in sparks should not be that difficult, or the CPU System that sensitive. :Artificial Intelligence".

Now, it won't pass emissions with that light on/error report

Your help, advice, and scolding is much appreciated..

I have to go to work, and I will check at lunch.

 

[Handy Andy]

No not scolding - but a good phone camera might help...

Ever try to see if you have "arcing" along the spark plug wires?

Good way to check this is simply drive the car, warm it up - put it in the garage with the lights off, at night - and DO NOT CLOSE THE GARAGE DOOR - don't get crazy about this idea...

Open the hood, be careful - do this with care so you don't place you, or the phone on moving hot parts - but then turn on the "camera" in your phone with the engine running in the dark room, Light off, no flashlight - set for MOVIE and low-light nighttime setting no flash - start recording - being careful - you can "Vid" the top of the engine block along the "spine" of the Spark Plug wires - slowly - and look for blue arcs or lightning along the path.

Some "cheap" plugs - their insulator can crack in two - in the ceramic casing - causing a open line to the outdoors from the center electrode to the side or nut/knurl of the plug. When the engine runs and if the insulator is compromised - the crack is now an air gap and the arc can easily shoot across - you'll see it as a "halo" or blue or cyan lightning color flashing as the plug attempts to fire,

• IF you decide to change plugs, look down in the bore of where that plug rests, look for rust and or oil - that may provide the reasons you might have a rough running motor.
• There are times that water and or dirty oil can soak the plug boot, making it less of an insulator - you can inspect the boot and look for worn or perforated sections of where the boot itself has burned thru from arcing.
• Loose spark wires that separate from the Boot - common cause of many a mis-fire and rough idle.

So this is caused the the compression stroke of the motor - having compressed air and fuel - it makes the arc in the gap harder to jump or form across to ignite the fuel mixture - instead it finds an easier path and jumps across the air gap outside the engine in the air gap of the insulator and jumps to ground at the nut instead - you see this "loss" as the arc forming to drain the energy away. IF your phones camera is sensitive enough, it can see this and it records the trip along the spine...

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Had several bout's with shops about Platinum plugs from Bosch - not getting shipped well, and arriving with chipped or cracked isolators ruining them - worse than buying a Heirloom glass vase from eBay and it getting smashed along the way - and you wind up with a box of broke shards - similar to this with spark plugs and cracks in their insulators.

If the plug wires are OEM and you have not upgraded changed them since - never - then you can also see how the wires can show a loss in the cracks forming in the old insulation - breaking down allowing gaps to form and allowing the electrical charge to arc ACROSS to other wires - losing power in the process.

This "discharge" is similar to "St. Elmos' Fire"

Neat and "Kewl" to watch - but don't play with it - it can hurt - even kill.​

Work along the entire spine - even to the transmission / battery side - when you see "arcs" jumping - there's your answer -- tells you, it will need new cables or module.

 

[scotman]

Plug wire sets should be replaced at the same time as the plugs. As the cables age they lose conductivity. I noticed that the fuel economy had been less. So replaced the plugs and wires. Problem solved.

 

[econoboxrocks]

Pre gapped plugs are in the ballpark, but not always. I'd check the gap, anyway. If it's perfect, you know that's not the issue. I'd then try new wires, like scotman said. They might look fine, but if they're old, they may be less conducive.