Dealer suggest injector flush for low compression

I have a 2005 GT turbo w/ manual trans. Now has 117K miles. Car has always consumed oil - about a quart per month since I've owned it, going on 2 years now.
Recently it started misfiring. CEL on, cruise light flashing.
Diagnostics returned low compression on #1 (60psi) and #2 (90psi), and plugs fouled, but mechanic says the leak-down test was "good" (no numbers). Cylinders 3 & 4 are around 130 psi each.

Naturally the warranty expired a couple months ago.

So the dealer (not a Subaru dealer) suggests replacing spark plugs and doing injector flush based on recommendation from a long-time Subie mechanic.

Obviously this is much cheaper than tearing into the engine to check valves and rings. They did not say whether they checked where the compression is being lost, i.e., crankcase or manifold.

So I'm skeptical. Does this have any chance of being a solution, or is it a waste of time & money?

If the compression is low and leadown didn't show any huge leaks, your looking at probably a ring problem. and there is no flush or anything that's gunna build the rings back up.

Waste of $ yes, they need to tear it apart and see what's wrong. Spark plug isn't a waste of $ though as you will need new ones

Burned valve and/or ring issue probably, so $$$.

Good luck and don't let the dealer do the work, just take it to a independent place that works on subarus or a tuning shop or something

The flashing CC light is normal with any CEL.

Like they said, change the plugs, drive it and start saving your money.

Your looking at around $6000 by the time your all done.

You'll need a clutch, FW and TSK3 kit too.

A Qt a month is may be not that bad, keep it topped off. How many miles is that ? For me that's over 2000 miles.

Thanks for the input everyone. Figured the injector flush job was a waste of $ - basically just flushing money out of my pocket.
@Max Capacity: It's OK to drive it after changing plugs? One mechanic said that it could send unburned fuel out the exhaust, to be consumed in the catalytic converter, thus leading to pre-mature failure and possible fire. I suppose good plugs will mitigate the unburned fuel issue.
Also: Why new clutch, FW and whatever a TSK3 kit is ?
Yes we put over 2000 miles per month on this car.

Since the engine is mostly trashed, would a little mechanic-in-a-can hurt anything? Might bring the compression back up a bit.

Before I replaced the short block in my wagon and the turbo the year before, I had used a couple of cans of Seafoam, a cleaner from the auto parts stores.

The old engine would use about a qt or more every 1000 miles. I never had a miss fire code.

I highly doubt your lossing that much fuel in the exhaust system. If you are losing fuel at that rate the miss fire will be very obvious. If the car runs much better, keep an eye on the performance for a while, see if it drops off.

I say change the plugs and drive it. You can't do much more damage.

Tell them you want to see the old plugs, look for oil fouling. Tell them to keep the plugs numbered so you know where they came from.

Guy's have also pulled the injectors and had them cleaned.



You have 117K miles, the OEM clutch is on it's last legs. The TSK3 kit is a thorw out bearing kit developed to replace the POS oem unit, that has been known to hang up and cause problems.

@Max Capacity: Oh the misfire was definitely noticeable - crappy idle, low power. Who knows, the compression could've been bad the day I bought the car. Maybe that's why the previous owner traded it.
Anyway, thanks for the info on this and the clutch & throw-out bearing.

Your welcome, read around here, you'll find lots of miss-fire threads.