Ford Focus 2000 LX used the wrong spark plug

2000 FORD FOCUS
97,000 MILES
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JESSICALAUREN
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A few days ago, I replaced the spark plug on my Ford Focus 2000 LX in a hurry. I accidentally used the wrong spark plug - I used a Motorcraft SP 478 instead of the SP 504. However, the descriptions on these two spark plug are identical. Would using the wrong plug be causing my engine to misfire?
Mar 19, 2012 at 3:34 PM
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RIVERMIKERAT
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It could. What about the specs on the 2 plugs? Heat range, etc.
Mar 19, 2012 at 5:27 PM
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RASMATAZ
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Yes, Big Time
Mar 19, 2012 at 5:28 PM
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KHLOW2008
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Yes, if spark plugs specifications are not what is recommended, it can cause misfirings as the gapping and heat range could be different.
Mar 19, 2012 at 5:29 PM
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