misfiring bog down

1999 FORD CONTOUR
137,000 MILES
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KELLYGHORMLEY
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  • 1 POST
Ran diagnostic test came back with 2 codes 3 cylinder misfire and back lean. Replaced plugs and wires with new ones. Ran another diagnostic test. Came back with 3&4 cylinder misfire and back lean. Replaced coil pack with new one. Also replaced thermostat because got stuck same day. The car still missing and when overdrive is on it runs worse what else could be causing this? Was running normal until 5 days ago this started. My check engine, light was staying on till replaced coil pack now it flashes periodically.
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May 11, 2013 at 12:27 PM
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HMAC300
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 48,601 POSTS
check fuel pressure low fp causes misfires
May 11, 2013 at 1:23 PM
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JERRYWEB
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I had the same thing, and after I replaced the plugs wires and coil pack, I replaced the fuel regulator. THEN... I noticed that the large O-ring that seats the cold air intake to the throttle body had dropped off the canister and was sitting on the back of the engine. Air was entering the throttle body causing extremely lean conditions, misfiring, hesitation during acceleration. I beat my self up trying to find the problem, turns out it was a $.30 o-ring! Once I seat the canister to the throttle body on the o-ring, all the trouble stopped!
Nov 18, 2014 at 12:46 PM