Recurring misfire with code P1131

Tiny
TFABE
  • MEMBER
  • 1999 FORD CROWN VICTORIA
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 270,000 MILES
Had cylinder misfire when purchased car. Replaced spark plugs and coils, ran great for couple days, started running rough. Trouble code said misfire #4 and 5. Cleaned plugs, ran good for couple days then rough again trouble code said misfire #3 and 4, clean plugs and MAF. Ran good couple days, then rough again. Trouble code said misfire #4 and 5, cleaned, re-gapped plugs, reset PCM. Ran good for about 4 days now rough. Trouble code now says misfire #1 and 3, also new trouble code P1131. What do I check or repair/replace next?
Sunday, May 16th, 2021 AT 9:02 AM

2 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

I would check the compression to be sure it is not an internal engine issue.

https://www.2carpros.com/articles/how-to-test-engine-compression

I would also check the fuel pressure to be sure there is good pressure. Low fuel pressure will cause this issue.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Roy
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Sunday, May 16th, 2021 AT 12:44 PM
Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Also if you bought aftermarket coils, they could be the issue. You might try sticking a few of the old ones back in if you still have them. In particular cylinders 1, 3, 4, and 5.
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Sunday, May 16th, 2021 AT 6:54 PM

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