How do you tell if a spark plug is bad?

+1 vote
asked Jan 26, 2018 in Other-Cars/Transportation by rajeeves (220 points)
How do you tell if a spark plug is bad?

How can you tell if you have a bad spark plug or bad spark plugs in your car?

1 Answer

0 votes
answered Jan 29, 2018 by Mechanic21 (29,150 points)
If you notice rough idling or hesitation when you accelerate then you likely have some faulty spark plugs.

You should pull one of the spark plugs out and check to see if it's fouling out or the gap is getting bigger.

If the spark plug is fouling or the gap is getting bigger then it's time for new spark plugs.

Spark plugs usually can be bought for around $20.00 to $30.00 per set so I would replace them if you have any doubt about them being bad.

You'll recoup that money you spent on spark plugs through your gas mileage savings.

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