2008 Subaru Legacy Rough Idle

RYNOBLASTER30

MEMBER
2008 SUBARU LEGACY
4 CYL
AWD
AUTOMATIC
20,000 MILES

Have what I consider to be a "rough idle." When cold starting the vehicle, it can be warm or cold outisde, the rpm's race to 1600/m. This lasts for 1-2 minutes before the car winds down. Durng this time there is a flood of exhaust. The dealer was made aware of the problems and they said they could not find anything wrong. Does this seem right? What bothers me more is the fast or rough idle.

5 Replies

SCOTTY DEE

MECHANIC
592 POSTS

Hey Rynoblaster! Has it always done that? This could explain part of it.
When the engine coolant temperature is approximately 158 °F or below, the ignition timing map in the ECU (Engine Control Unit) is changed to retard the engine timing. This timing change is done in order to quickly heat up the exhaust catalyst to reduce emission gases. This change causes part of the combustion process to occur as the exhaust valves are opening in the cylinder head.

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Wednesday, February 24th, 2010 AT 9:01 AM

LEGITIMATE007

MECHANIC
5,121 POSTS

What color is the smoke? Also I would like you to clean the throttlebody, really well, and clean the throttle plate too. You may also want to lubricate the throttle cable, I suspect the plate or cable is sticking, is there a check engine light on?

Was this

answer

helpful?

Yes

No

Wednesday, February 24th, 2010 AT 9:06 AM

RYNOBLASTER30

MEMBER
3 POSTS

White colored smoke with a strong exhaust odor. No check engine light comes on.

Was this

answer

helpful?

Yes

No

Wednesday, February 24th, 2010 AT 10:56 AM

LEGITIMATE007

MECHANIC
5,121 POSTS

Just as I suspected, I suspect you have a blown head gasket, it may be small at this point but before you know it it will get bigger, and you wont be able to drive at all

Was this

answer

helpful?

Yes

No

Wednesday, February 24th, 2010 AT 11:51 AM

LEGITIMATE007