LOOPES AND BACKFIRING WHILE IDLE

  • Tiny
  • tmaj9447
  • 2002 Ford F-150
  • 308,000 miles

Hears the deal; this all started when I changed the spark plugs. Truck ran fine I was just doing pms. Changing the plugs ended up with having to rethread one of the coil pack bolt holes in the intake. One that was repaired I installed new upper and lower intake gaskets, torqured everything to specs, installed 2 new coil packs (broke 2 getting them out), replaced all 8 plugs with ngk oem replacements, buttoned everything up and to my suprise this lopeing and sounds like intake backfiring. Please help! Engine is a tritron 4.6

Thursday, May 24th, 2012 AT 9:53 PM

7 Answers

  • Tiny
  • rasmataz
  • Member

Go to this link: http://www.2carpros.com/articles/engine-backfires-while-running

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Thursday, May 24th, 2012 AT 10:05 PM
  • Tiny
  • tmaj9447
  • Member

Checked fuel pressure at rail 40 psi

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Thursday, May 24th, 2012 AT 11:33 PM
  • Tiny
  • tmaj9447
  • Member

If this helps rpm goes from 700 to 1500 radically.

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Thursday, May 24th, 2012 AT 11:34 PM
  • Tiny
  • rasmataz
  • Member

Check for vacuum leak and clean the idle air control valve and see what happens

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Friday, May 25th, 2012 AT 1:00 AM
  • Tiny
  • tmaj9447
  • Member

Okay still no change, I took the 4 spark plugs on the rightside out and they are sooted and dry. Should I check the injectors, seems like it is not getting fuel to the cylinders. Not sure

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Friday, May 25th, 2012 AT 12:24 PM
  • Tiny
  • tmaj9447
  • Member

Lower intake gasket, replaced and runs as expected. Vacuum issue solved. Thanks!

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Friday, May 25th, 2012 AT 7:05 PM
  • Tiny
  • rivermikerat
  • Expert
  • 6,174 posts

Or pleasure. Happy to help.

Closing thread.

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Friday, June 1st, 2012 AT 2:17 AM

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