1995 Mercedes Benz S420 MISS FIRING

1995 MERCEDES BENZ S420
130,000 MILES • V8 • 2WD • AUTOMATIC
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SLOUIS123514
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i DID PUT NEW SPARKPLUG, NEW ROTOR, NEW ROTOR CAP AND NEW IGNITION CABLES. HOWEVER THE ENGINE STILL MISS FIRE, ALSO SOME SPARK PLUG WHEN REMOVED WERE WET OF GAZ. AND SOME ARE HVE BLACK CORBON ON. CAN YOU HELP?
Jul 8, 2009 at 10:25 PM
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2CARPRO JACK
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I have forwarded your question to our M/B tech. He will be with you shortly, thank you for your patience
Jul 9, 2009 at 7:58 AM
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GFIMOTORCARS
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  • 673 POSTS
  • ASE Certified Mechanic
This vehicle model is known to have issues with the fuel pressure regulator. In most cases the regulator leaks internally causing unregulated fuel to enter the combustion chamber creating a rich running condition (wet and carbon fouled plugs can be caused by this). This will then result in a misfire conditioon with poor idle quality.
Jul 14, 2009 at 11:49 AM
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