very rough idle MY05 GT

[LibertyGT2]

I reported this to the dealer on at least 10 occassions and they changes O2 sensors a few times and cleaned the injectors and still the issue would come and go as well as intermittent CELs (O2 sensor)

The issue instantly disappeared after I had my computer retuned in Melbourne at STi.

Tim

[teflon]

Mine has had this problem for about 3-4 weeks but the engine light hasn't come on yet. It's starting to annoy me but most of the dealers i've spoken to said it's better to wait for the engine light to come on before getting it checked out...

[gt2nv]

does any1 know how you can tell the difference if its the 02 sensor, fuel injectors or just a re tune that is needed to fix the rough idle when in park and neutral?

[LibertyGT2]

does any1 know how you can tell the difference if its the 02 sensor, fuel injectors or just a re tune that is needed to fix the rough idle when in park and neutral?

If you have a Check Engine Light (CEL) on, you need to have the computer read to diagnose.

If no CEL, it could be any or all of the above. Does it idle rough with your A/C turned off? or only when it's on?

[gt2nv]

when the a/c is off i went to my mechanic he said he thinks it could be the spark plugs or a coil but i had the major service done only 3 months ago ???

[Breeze91]

I had this problem. The car would idle ok when cold but as soon as it warmed up it would have a slight continual stumble, many people just expect that with a subaru motor and say it is particular to the motor. All my older subarus did it and it is one of the reasons I moved away from subaru.

These new ones can hold an almost perfect idle and I knew it was achievable so I kept at it.

The other time it was REALLY noticable was at about 60km/hr in 4th or 5th, or any gear at low revs. Slight surging. Basically it was a sticking injector which wouldn't open well at low duty cycle.

Fortunately I owned two identical legacy GTs at the time. So I started a process of elimination from easy to hard.

1 Swapped the MAFs - no change
2 Swapped the wide band o2 sensor (the top one) - no change
3 Put in new plugs - no change
4 Swapped the coil packs - no change
5 Swapped the injectors - instant fix and the other car then had the problems

Tried getting the injectors cleaned professionally and they still did it. In the end bought 1 new injector and with a process of elimination found the bad one. Getting at the injector is a pain (especially on a hot motor).

Now my other one started getting poor fuel consumption and surging also at low speed and the ECU light would not come on and it was my wideband O2 sensor. Replaced that and it was perfect again. Keep at it you will be so pleased when it is running right again.

[jslayz]

My 05 GT BP5 used to have a little surging on very light throttle and sometimes when idling it would really shudder as the a/c came on.
So I thought 'injector?' and ran 2 tanks with the Nulon injector cleaner/octane booster $15 a bottle.
Now it's a lot smoother and seems to spool up faster, definitely something blocked before!

Maybe give that a go before spending $$$'s

good luck with tracking it down.

J

[SPOOL UP]

05 lgt The same issue, everything is ok idles fine 15 minutes after warmed up, my tach stuck on 700 rpm, but its body shakes like crazy, No check engine light comes on, At cruising speed runs smooth, I dont understand ?????? .

[Boost]

mines got similar idling symptoms Andrew.
I bought the car only a few days ago at a used dealer (part of the Sutton's group) so I'm taking it back there tomorrow under the 3 months warranty the car comes with. I hope they don't come back to me saying the part is not covered under the warranty as this will really pee me off. Lets see what they say.