Changed spark plugs now engine idles rough and knocks when in reverse

2016 JEEP COMPASS
10,000 MILES • 2.4L • 4 CYL • 4WD • AUTOMATIC
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TOXICWRATH26
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I changed my spark plugs from NGK zfr5f-11 to Champion 318cc (RC12MC4) and before I got the wrong size they did not fit but some how it got stuck in their spark plug hole. I had to fish it out with needle nose pliers not much of a problem then went and got the proper plugs and everything went in the way it is supposed to, but when I start the vehicle the engine shakes like crazy and when I put it in reverse it has a pretty loud knocking sound. I know it is December 23, but I need help ASAP. Please someone help!
Dec 23, 2017 at 7:29 PM
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HARRY P
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The NGK plugs are Nickel core plugs. The Champion ones are Copper core plugs. That's probably your issue right there. Nickel core plugs give a hotter spark than copper core plugs do.

When you changed the plugs, did you pull all of them out at the same time? Or did you pull 1, replace it, put the wire/coil back into place, and then move to the next plug? If you did it the first way, then I bet you accidentally switched 2 of the wires/coils around. This is a very common mistake that people make, and it's why you should always do your plugs one at a time.

Also, make absolutely sure that the coils are properly connected to the plugs, and that their connectors are snugly connected as well.

Let us know and we'll go from there.
Dec 24, 2017 at 4:00 AM
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ASEMASTER6371
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Good morning.

Just to add to the last tech make sure the plugs you installed were gaped properly. If one was dropped and closed the gap, it would explain the miss.

Roy
Dec 24, 2017 at 4:07 AM
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TOXICWRATH26
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Does that really make that much of a difference when I looked online it said it was compatible but ill give that a shot

The wires are only long enough to for the coil to goin the proper hole of the spark plug and i did check it several times
Dec 24, 2017 at 4:09 AM
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HARRY P
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Yeah I looked it up and I do see what you're saying about the coils. And yes, spark strength is basically everything. I always only use the stock plugs in my cars. In this sense, manufacturers generally know what's best for their cars. Also, as ASE suggested, the gap can make a difference too. I always check the gap of the plugs before installing them, even if they're supposed to be pre-gapped.
Dec 24, 2017 at 4:13 AM
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TOXICWRATH26
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Ok well i will be trying that in the morning for sure i thought my coil might have gone or something ....would that cause a knocking when I put it in reverse
Dec 24, 2017 at 4:16 AM
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HARRY P
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Delayed ignition due to weak sparks will cause that noise when you put the engine under a load ie putting it in gear. Your issues all seem to circle back to the plugs. I highly suggest going back to the OEM plugs. If there was something wrong with them, get new ones. Just my opinion.
Dec 24, 2017 at 4:22 AM
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TOXICWRATH26
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Yeah Im absolutely going to do that I will let you know
Dec 24, 2017 at 4:24 AM
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TOXICWRATH26
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Okay that did nothing at all. i also changed the ignition coil for the number one cylinder and that has not done anything either. not knocking when i reverse but still shakes and no check engine light comes on.
Dec 24, 2017 at 12:11 PM
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HARRY P
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Let me ask you this: What was the original reason for changing the plugs? Was it running roughly or burning a lot of fuel? If so, being a 2016, is it not under warranty?

And you really cannot say that it did nothing when the knocking sound went away.
Dec 24, 2017 at 7:32 PM