Ford Focus 2000 LX used the wrong spark plug

Tiny
JESSICALAUREN
  • MEMBER
  • 2000 FORD FOCUS
  • 97,000 MILES
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?
Monday, March 19th, 2012 AT 3:34 PM

3 Replies

Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
It could. What about the specs on the 2 plugs? Heat range, etc.
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Monday, March 19th, 2012 AT 5:27 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Yes, Big Time
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Monday, March 19th, 2012 AT 5:28 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Yes, if spark plugs specifications are not what is recommended, it can cause misfirings as the gapping and heat range could be different.
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Monday, March 19th, 2012 AT 5:29 PM

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