Forester STI – Spark Plug Change

Time for some new spark plugs and while I’m at it an upgrade to a cooler running plug in preparation for more boost, more on that another time. From what I read, the spark plug to go for is the NGK ILFR7H.

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This is more of a job than with most other cars due to the engine being a flat/boxer arrangement. Limited space either side of the heads is the problem but it’s still doable without too much trouble, it’ll just take longer than a simple inline 4 or 6 might.

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Starting on the left side. Air box needs to come out.

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Two bolts to remove the air box.

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Here you can see the coil packs.

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Two variations of extensions or adapters to get just the right length.

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One side done, on to the two the other side.

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Battery and washer bottle removed. Then this is the same as the other side but with it being more awkward to remove and refit the coil packs.

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Job done. Ready for more boost now but there are some other things to do first to get the most out of the engine come remap time.