91 318is (M42 engine) Idles and runs rough

1991 BMW 318
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DMSSEYJ
  • MEMBER
  • 2 POSTS
235k mis. 5sp.
Idles rough and runs rough till about 2500 rpm then runs just fine unless dips below 2500 rpm again. Am pretty sure it is one cylinder not firing but not sure what to do about it.
Jun 18, 2007 at 6:12 PM
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BRUCE HUNT
  • ✓ASE Certified Mechanic
  • 3,754 POSTS
  • ASE Certified Mechanic
Pull of the plug wires one at a time until one of them being pulled off makes little or no difference in the running of the engine. When you find the one start with replacing the plug. If there is no spark there however from the plug wire, replace the wires on the vehicle.
Jun 18, 2007 at 11:06 PM
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