# '71 Volvo rough idle



## ukrkoz (Dec 31, 2010)

Go here:
http://www.rotaryeng.net/Spark-plugs/Spark-plugs.html
Scroll down to color chart, find your plugs, and read what it means.
Wanted to say - you run lean on those 2 plugs, ha-ha, indeed:
_A clean, white insulator firing tip and/or excessive electrode erosion indicates this spark plug condition. k This is often caused by over advanced ignition, timing, poor engine cooling system efficiency (scale, stoppages, low level), a* very lean air/fuel mixture,* or a leaking intake manifold. When these conditions prevail, even a plug of the correct heat range will overheat._
Clean fuel injectors.
http://www.youtube.com/watch?v=7aT4S1lIBAY


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## msmith5554 (Apr 13, 2012)

Sounds like you have a vacuum leak. With the engine idling, spray mist of water around the engine area. The engine will start to die or run rough if the leaking area gets sprayed


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