Why is my Subaru Impreza idling so low and dying, sitting or even when driving and I put the clutch in... She will die! What's wrong ?


Asked by Nov 06, 2015 at 09:31 AM about the 2005 Subaru Impreza 2.5 RS

Question type: Maintenance & Repair

Cylinder 1 misfire, I've replaced the wires,
coil pack, and MAF and air filter moving on
to spark plugs. The car was running fine until
I replaced the coil pack. And I replaced it
anyways because I didn't want the problem
to progress. Thought it might be the wires so
I replaced them too, didn't help. Replaced
the MAF and it still idles low and dies if I
leave it alone. I also changed the air filter
because it looked pretty bad. I just bought
this car and two days later this happen.
What do y'all think?
Subaru Impreza 2005 2.5 non turbo, I believe
a single cam.

1 Answer


MsAx, Nice Subie! '02-'07 Imps are fabulous handling, albeit a bit brash and noisy. I'm going to guess that the very fine gap between the throttle body butterfly plate and its bore is gummed up over time. Pretty easy service: remove the air hose/plenum in the rear, then spray liberally the inlet with carb cleaner, wiping clean with paper towel; THEN, IMPORTANTLY, stick your fingers in there and force the butterfly open and try to hold it horizontally in place while you spray the inner bore both top and bottom, wiping the sludge out as best you can; repeat until you think it's pretty clean. Note that restarting will be tough (and possibly smoky...sorry!), as the motor chokes on all the cleaner, but after a couple of minutes you'll probably have a much smoother idle. The problem isn't that the gunk was CAUSING the rough idle, but that it was blocking the small amount of air needed for the idle circuitry (its sensor plugged in there) to maintain a smooth idle. he gunk was acting to "choke" off the air supply. This is a pretty good service to perform every 5-6 years, and costs nothing. Do try to avoid breathing the spray carb cleaner. If you have a CEL be sure the problem isn't just a water temp sensor; as I recall these $15 sensors (which incidentally sit just below the TB where you're working) can screw up low speed running too, as the ECU doesn't know whether you're warmed up or not, and messes up idle stability. If I remember this sensor throws a CEL if bad. Have fun, and wear rubber gloves. Ern

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