Rough Idle

**Spenc13** · #1: 01-21-2013, 09:56 AM

Hello,
I have a 2006 Subaru Legacy 2.5GT with 129,000 miles on it and it has been idling extremely rough when I put in the car in drive and will even stall out sometimes when the temperature is around 20 degrees or below. Any ideas on what the problem could be?

**DOHCstunr** · #2: 01-21-2013, 10:31 AM

Any codes?
I would start by checking your spark plugs and testing your coil packs.

**06silvarubiLGT** · #3: 01-21-2013, 10:40 AM

Intake manifold O-rings... Spray some carb cleaner around the TGVs when at idle and see if it changes

**Mr. Sinister** · #4: 01-21-2013, 11:28 AM

^ If it's only happening when cold, yup.

**Spenc13** · #5: 01-29-2013, 08:42 AM

Spark plugs have been replaced within a year. I sprayed around the TGVs when at idle with carb cleaner and nothing happened. The car still continues to idle rough when in drive if it doesn't stall completely. It seems to be getting worse as it was only about 48 outside when it stalled the other day. Any other ideas of what could possibly be wrong?

**Spenc13** · #6: 01-29-2013, 08:44 AM

DOHCstunr --->> No check engine light or codes.

**Mr. Sinister** · #7: 01-29-2013, 08:56 AM

Quote:

Originally Posted by Spenc13

I sprayed around the TGVs when at idle with carb cleaner and nothing happened.

Did you spray around the areas where the intake manifold mates to the head? The intake manifold o-rings are one common leak, the TGVs are another (less IMO).

Also, have you done the usual checks for vacuum leaks?

**Max Capacity** · #8: 01-29-2013, 10:54 AM

The o rings are a known problem area on these cars when its cold outside.

**fysics** · #9: 01-29-2013, 03:12 PM

here's the thread on the o-rings if it's an only when it's cold kinda thing.
http://legacygt.com/forums/showthrea...09-155325.html

the deal with mine was idle was rough until the engine was up to temp with about 20minutes of driving, not just until the blue engine temp light shut off. I had the rough idle plenty of times with no CEL, then that finally came on a few times. was enough to get me going on the fix.

I just did this myself and it's looking like it's cleared up my idle issues!

**joshcwang** · #**10:** 01-30-2013, 12:37 AM

seafoam through my bpv line always cleared out any rough idling and gives me better mpg

or it could be the o rings...but nevertheless...never hurts to seafoam your car every 12-15k miles just to get rid of all the burnt up crap in your motor and to clean your injectors. I always do it right before a tune to make sure everything's perfect

and try not to inhale the smoke