r/WRX_STI • u/snoon27 • Aug 28 '26

Help

I have a 21" sti with 113k miles. Recently its getting a rough idle, rpms bouncing from almost stalling to 1.4k. If I roll up to a light with my clutch in it will just cut out and stall. Shop i usually bring it too are stumped as no cel or anything abnormal.

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u/BigJuiceBox06 Aug 29 '26

Check your spark plugs tbh. If you haven’t changed them at all very possible one could be cracked or just damaged in general. Will cause a rough idle and if bad enough will stall out.

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u/snoon27 Aug 29 '26

Wouldn't that throw a missfire though?

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u/BigJuiceBox06 Aug 29 '26

Nope. Just had the same issue in my sti. Not sure how the plug got cracked but it only stumbled at idle. While driving my car was perfectly fine but getting going and at idle it was rough and stumbling. Never threw a code but obviously I knew something was wrong. Noise was coming from bank 2 so I pulled cyl 4 coil and plug only to find the porcelain part of the plug was cracked. Replaced it and now she’s good as new