Hi all. I have a '71 Volvo 1800 that has a strange idling problem. When I first start it up, it idles fine, but then all of a sudden, around 30 seconds or so into idling, it drops down significantly. It's a 4 cylinder engine and 2 of the spark plugs have white tips, but all of the injectors are "squirting" appropriately. Does anyone have any idea why this might be happening? Thanks!
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.