Purpose and Design
One step colder spark plugs is a common practice on tuned vehicles to safeguard any chances of preignition or knock in the engine. Since tuned engines provide a higher volume of air to the cylinder, this air is often hotter and faster than before. Accordingly, the spark plugs themselves must have a colder heat range to avoid any preignition in the cylinder before the desired time. This can cause a world of problems like engine knock or even blowing a hole through the engine block in extreme cases. One step colder essentially means to close the gap of the two electrodes in all of the spark plugs manually by a small degree. In this scenario, I changed the gap from 0.026 inches to roughly 0.024 inches using a simple feeler gauge. The performance ignition coil packs were used to provide a faster more reliable current to the spark plugs along with a more robust reliable design than traditional OEM coil packs.
Removal of Inlet Pipes, Engine Bay Bars, and Cabin Filters
Although you can see a few coil packs in this picture, being an inline 6 many cylinders are tucket away deep into the engine bay. To access these comes a grueling process of removing many bars, plastic covers, and pipes in the engine bay. First, the blue arrow points to an inlet pipe that must be removed to expose a cylinder 3 and 4 underneath it, then the pipe pointed to by the green arrow must be removed to completely expose this section. The yellow arrow points to a vaccume tube that must be carefully removed from the second inlet pipe to fully release it from the engine. This pipe is often very brittle and easy to crack so care must be taken. Finally, the white and red arrows point to all of the coverings on the end of the engine that will expose cylinders 5 & 6, allowing the job to be started.
Finally, it will look like the picture on the right, exposed and many extra cylinders open(this picture is not how it looks when opened, the red is the aftermarket coil packs already installed).
Coil packs and Spark Plugs
Next, I had to remove the coil packs and spark plugs themselves. The coil packs(on the left) come out easily, after the removal of the wiring that provides the voltage for the spark plug, the coil pack can simply be pulled upwards with a satisfying "pop" to signify it pulled out cleanly. It can be inspected afterward for water damage, corrosion, or any other signs of further damage. Next, using a special spark plug socket specific to BMWs, a long socket wrench must be carefully lowered into the cylinder head and placed on the spark plug. After removal, the spark plug should also be checked for corrosion or water damage, specifically on the electrode, which could signify more serious issues. I bought NGK laser iridium spark plugs to provide more performance capability, longer lasting design, and lowered chances of misfires. After gapping spark plugs correctly(left bottom picture), as explained above, they may be installed the same method they were removed, along with the coil packs afterward. The picture shown is 3 of the 6 red performance coil packs installed.
Image from FCP Euro of socket wrench
in spark plug chamber
