Re: Help!!! Changed spark plugs, Now rough idle (archive)

Make sure you didn't transpose the wires, put 4 where 3 should be, because it sounds like a classic miss. The problem has to be in the wires or their connection. One more thing to check is that the new plugs aren't cracked, shut off the lights in the garage and start the car with the hood up and look for spark jumping. Just be sure you do this with your garage door open! Carbon monoxide fumes build rapidly and are deadly! Hope this sheds some light on the problem.
Jr
'89 535iA
Sharked&Cleared

I changed the OEM Bosch spark plugs that had 60,000 miles on them with Bosch Platinum +4 (Part# 4417) plugs . Now the engine seems to idle rough. It does not seem to run as smooth as it did with the old spark plugs. When I started the car this morning the car sputtered and was rough starting. Normally the car starts up very smoothly and runs smooth after warm up. The car seems to also have a slight tapping as if a valve was tapping but it could be my imagination. The plugs where the same physical size and where easy to install. What might be the problem? was I given the wrong parts? Did i mess something up? Any and all help would be greatly appreciated.
Thank You
John W. List
1995 525 iA
166K miles

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