After replacing spark plugs and tightening to the specified torque, started the car and it started as expected. When I tried starting again after it was sitting idle for two weeks or so, it will not start. Went through many forums without any help. Some mentioned about defective plugs although new. Never experienced defective new plugs before but decided to put the old plugs back to see if it will start. To my surprise, the new plugs came out without any effort, although they were tightened to 2 3 ± 3 N m ( 1 8 ± 2 f t - l b ). Replaced #1 plug and hand tightened using 6 inch ratchet and re-tightened the remaining 5 the same way. Stared the car and it stared without hesitation. Replaced the #1 plug with new plug and problem solved.
Because I had visited many forums for help, I wanted to share my findings with the DIYers.
I'm sorry but I'm unclear as to your solution: did you remove ALL 6 of the new plugs and reinstall the 6 old plugs, or did you have to simply replace ONE of the new plugs?
2007 530i sport (Montreal Blue w/ gray interior)
2008 550i sport (Alpine White w/ black interior)
Sorry for such a late response.
What I found out was that the spark plugs were not tight enough to create required compression. To troubleshoot the issue, I just replaced the spark plug in #1 cylinder with the old plug but in the process of doing so I realized how essay it was to unscrew the new spark plugs which were installed about two weeks back.
In a nut shell, the problem was with plugs not torqued enough to create required compression in the cylinders. It is very likely that I did not set the torque meter to the correct value.
Interesting thread. The only thing that comes to mind other than incorrect torque setting is if the old plugs were hard to take out maybe the threads were a little resistant to accepting the new spark plugs and they felt like they seated all the way. When applying the torque wrench the resistance enabled the torque setting to be reached. Just a guess. I agree with the seat plugs and then 1/4 to 1/2 turn thereafter. I have been turning wrenches for so long there are plenty of bolts and nuts I do not torque, but go by feel.
Yeah, but a partially threaded spark plug would not relieve compression appreciably. Something else must have been wrong, like perhaps improperly connected coils.
Bookmarks