2008 Subaru Legacy Rough Idle

Tiny
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.
Wednesday, February 24th, 2010 AT 8:51 AM

5 Replies

Tiny
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.
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Wednesday, February 24th, 2010 AT 9:01 AM
Tiny
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?
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Wednesday, February 24th, 2010 AT 9:06 AM
Tiny
RYNOBLASTER30
  • MEMBER
  • 3 POSTS
White colored smoke with a strong exhaust odor. No check engine light comes on.
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Wednesday, February 24th, 2010 AT 10:56 AM
Tiny
LEGITIMATE007
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  • 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
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Wednesday, February 24th, 2010 AT 11:51 AM
Tiny
LEGITIMATE007
  • MECHANIC
  • 5,121 POSTS
I suspect you have blown head gasket witch will need repair, very soon.
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Wednesday, February 24th, 2010 AT 12:11 PM

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