Replacing the spark plugs on your BMW E90 is part of routine maintenance. BMW recommends replacing the spark plugs on E90 normally-aspirated models every 100,000 miles and turbocharged models every 45,000 miles. With all the major engine design changes over the years, spark plugs now last up to three times as long as they did in years past. This is good and bad. It means you save money and time not having to service them so frequently, but run the risk of a spark plug seizing in the cylinder head. I suggest replacing your spark plugs every three years regardless of mileage. If the last time they were serviced is unknown, replace them right away.
BMW E90 models utilize an individual ignition coil for each spark plug, referred to as coil over plug. (green arrows) The coil is a new design used in late model E46 and all E90 models, referred to as pencil ignition coils. This style coil no longer uses fasteners to hold it down in cylinder head, instead using a friction fit.
When servicing your spark plugs, be sure the engine is cool and leave yourself about an hour to do the job. Be careful not to drop a spark plug, if you do, replace it. The spark plug insulator can crack and can lead to an engine misfire.
Remove engine cover on cylinder head. See our tech article on engine cover removing.
Remove ignition coil from cylinder head by pulling straight up. If coil resists, twist when pulling up to break free from spark plug. The ignition coil rubber boot can become stuck to spark plug over time.
You can also use a flathead screwdriver to lever coil up and out of cylinder head. Be very careful using this method as coil is made of plastic and easily damages.
If you find engine oil has contaminated the ignition coil boot you will have to repair the oil leak and replace ignition coil. The source of the oil leak will likely be the valve cover gasket.
Using a 5/8 thin-wall spark plug socket on a 12” extension, remove spark plug from cylinder head.
If your spark plug does not fit into spark plug hole, you can remove the ignition coil insulator from valve cover. Use 90° tip snap ring pliers to grab insulator holes and squeeze, then pull insulator up and out of cylinder head. This is for vehicles with plastic valve covers only.
Turbo-charged models require a special spark plug socket. The spark plug requires a 12 point socket available through Pelican Parts, part# XXXXX (BMW part# 83 30 0 495 560)
Lightly lubricate new spark plugs with copper based anti-seize. Thread spark plugs into cylinder head by hand, this will prevent accidental cross-threading. Torque spark plugs to 23 Nm (18 ft-lb). Reinstall ignition coils and reconnect electrical connectors. Be sure to route wiring harness as it was before and connect ignition coil grounds. Install engine covers and check your work.
Comments: FWIW - I purchased a set of Bosch coils from the local BMW dealer today at the commercial parts counter where I am pretty tight with the crew knew a few guys from other jobs over the years. They report BMW appears to be switching to the Delphi coils, and noted it must be a product quality issue as that's when they normally witness migrations between suppliers. Bosch is still available, but BMW recommends moving to the Delphi where possible. Price is equivocally the same in the system for either type.
August 18, 2014
Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
Comments: To Beefeater & Pelican. I've a 2006 325i, and I've replaced all the ignition coils with the OEM Bosch coils grey color and NGK plugs. I also noticed the problem you've describe, looks like it is not making a tight contact with the plugs electrodes. The original ones snapped in the plugs with solid contact. Just wondering if there is an updated version of the spark plugs for these coils?
August 12, 2014
Followup from the Pelican Staff: I do not believe there is an update. - Nick at Pelican Parts
Comments: I did not see springs inside the coils and I have submitted my question to Delphi. I will update you.
August 7, 2014
Followup from the Pelican Staff: Thanks, keep me posted. Would like to know what you find. - Nick at Pelican Parts
Comments: I have new Bosch R6 plugs and new Delphi coils. I notice that there is an air gap of about 1mm between the coil electrode and the plug electrode i.e. with the plug seated in the coil, the plug can be pushed in until the electrodes touch, and when released, the plug resettles with an air gap. So, in operation, does the spark jump from the coil to the plug? Or should they be in contact with no air gap? Many thanks.
August 6, 2014
Followup from the Pelican Staff: Inside the coil should have a spring that makes contact with the spark plug. Is this not the case with your vehicle? - Nick at Pelican Parts
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