tire 10 Report post Posted June 25, 2008 (edited) I took the spark plugs out of an M10 (not the M10 in my car). Some questions. 1. They are W8DC. Yet Bentley says the E30 318i takes a WR9DS. What is the difference between these 2 plugs? 2. Do spark plugs all get replaced at the same time? Because I noticed 3 of them had a reasonably clean thread but on the 4th the thread was noticeably more blackened. All 4 Had good normal electrodes no excessive carbon deposits or oil fouling. 3. Hot does one decipher spark plug codes? Cheers Edit, spelling Edited June 25, 2008 by tastic Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 25, 2008 Bosch bible says W8DC or WR78-4PK Dont worry about black threads. It probably wasnt tightened properly Quote Share this post Link to post Share on other sites
tire 10 Report post Posted June 25, 2008 Bosch bible says W8DC or WR78-4PK Dont worry about black threads. It probably wasnt tightened properly Cheers Glenn. Why would the bentley manual be saying WR9DS? Does the electrode gap decrease with the size / power of the engine, generally? I notice bentley recommends .8mm for 318i vs 0.7mm for 325 hence the curiosity. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted June 25, 2008 .8 is fine The different gaps are given in Bently just to confuse Yanks Quote Share this post Link to post Share on other sites
sp8s 1 Report post Posted June 26, 2008 .8 is fine The different gaps are given in Bently just to confuse Yanks :D Quote Share this post Link to post Share on other sites
