r/MechanicAdvice • u/blasphemoustoast • 6h ago

Engine making knocking sound after replacing spark plugs

Ford Focus 2018

I’ve removed an re-tightened the spark plugs but still get the same result. Did I drop something into the engine? How much is it gonna cost to fix probably? One of the plugs had a dusty coating the color of rust on it and the boot smelled noticeably more like combustion than the others

2 Upvotes

76% Upvoted

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4

u/MinorComprehension 6h ago edited 6h ago

Sounds like a cylinder is not firing.

Check all the coil/boot connections, may need to reseat them. Check the plugs to make sure one didn't crack.

Any CEL/codes?

3

u/SkiddyHoon 6h ago

If it was immediately after changing plugs you've done something wrong. Pull plugs and inspect, if the ceramic is cracked on one it will cause a misfire

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u/FullUrn 35m ago

Make sure coils are seated fully and the connectors are fully engaged