OBD code 0304 (misfire)

204,000 MILES
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ATOMICDR
  • MEMBER
  • 49 POSTS
The misfire is in hole 4 (if that's the one closest to the tranny). I did have a code 0420 (catalyst...) but it never returned after clearing the codes the first time....(old code?). I pulled the #4 plug and inspected. It appears fine. Looked in the piston hole... looks normal. After sitting all night it started right up and ran on all cylinders. Shortly thereafter..
less than 10 minutes running time it started again with the misfire... running on only 3 cylinders. I'm thinking this may be a heat-related issue with some component of the ecm or other electrical issue.... where now?
Dec 31, 2011 at 1:49 PM
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FIXITMR
  • ✓Experienced Mechanic
  • 9,989 POSTS
maybe ignition coil.
Dec 31, 2011 at 2:40 PM
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FIXITMR
  • ✓Experienced Mechanic
  • 9,989 POSTS
watch spark on that cylinder on cold start and watch again when has miss. use spare plug and maybe widen gap.
Dec 31, 2011 at 2:41 PM
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