97 e 420 rough idle

Tiny
SEVENTHUNDERS
  • MEMBER
  • 1997 MERCEDES BENZ E420
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
97 e420 runs and starts great but has rough idle always
Sunday, December 12th, 2010 AT 1:47 AM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Engine running rough or misfiring can be cause by the following:

1. Defective spark plug.
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. Vacuum leak
5. Fautly fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.
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Sunday, December 12th, 2010 AT 1:51 AM

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