MY 06 EJ252 (Hesitates/Sputters)

[Black Sub]

My Liberty 2.5i hiccups and sputters on a light throttle opening. It's worst when it's cold. If I drive it long enough
30-45 minutes the problem becomes almost non existent. Occasionally (after 30- 45 minutes) there's a very brief reluctance off idle.
After 30- 45 minutes if I give it a large accelerator command it goes as good as ever.

There's no check engine light and I've plugged my (cheap) OBD II reader into the car and there's no codes.

The no code diagnostics in the factory manual list 8 or 9 possible components that will produce the symptoms
I've described, but I cant find anything in the manual that gives information on checking the health of those
8 or 9 components/systems.

Has anybody got an idea of the most probable cause??? or even know of a decent Subaru Tech/Mech? I'm well West of the Melbourne CBD. So a Tech West or North of the Westgate bridge would be good, as the traffic on the Westgate is hideous these days... its bad enough getting across on my bike let alone driving across

Cheers,

Alan.

[Ric]

Just an educated guess, one or more injectors may be getting a bit sticky, and not opening effectively for very short pulses.
Whatever is gumming it up might soften as it gets hotter.
A bottle of injector cleaner may help.

[Black Sub]

Thanks Ric. I added a bottle of injector cleaner about a week ago... I'm about a third the way through the tank of fuel that the cleaner is in and no change at all yet.

Regards,

Alan

[Yowie]

Do the symptoms occur when the car is under load or at "no load" too?

(if "always under load" we'll discuss farked knock sensors)

[bigBADbenny]

I can help out in Melbourne, we have a 320kkm preFL 2.5i and they’re easy enough to get sorted by addressing a few fundamentals.

We cleaned the pcv valve and used Subaru upper engine cleaner and injector cleaner, cleaned the throttlebody: opened with the throttle, not manually, upgraded the plenum to throttlebody clamps with Norma screw clamps, ensured no inlet tract leaks/inlet pressure test, replaced the engine oil cap oring and the dipstick handle oring, and replaced the dead fuel flap with a matching flap from an H6.

This last mod ensures everyone fills up with 98 meaning no more pinging ever

I guess after all that I performed an idle relearn for good measure.

Outlier issues include intake manifold gaskets, injector seat seals, fuel purge valve etc. most of this you can confirm with inlet pressure testing.

The mighty 2.5i is Subarus doomsday chariot, n00bz who are underwhelmed with them must be lacking in other departments, or theirs were driven for so long with basic issues they’re self destructing.

If you’re pushing through what feels like limp mode, no cel/dtc, then check your brake lamps, a dead bulb will hobble the engine amazingly.

They just need sympathetic fettling as above and new shocks and refurb GT brakes.