Cold idle problem

[mikeyd90]

Got a 97 legacy outback, but a subaru mechanic swapped out the 2.5L engine with the 2.2L before i bought it. It's driven almost 9,000 miles since then seamlessly, but now I think i have a problem with the choke. When i start it up when it's real cold out, it'll start right up and go to a normal cold temp start RPM, but when i let the clutch out and take off in first and shift to second, when i let off the gas and hit the clutch, the engine revs up and stays around 4000 rpm until i let the clutch out and the clutch pulls the rpms back down. It does this until the engine's warm, then it runs perfectly normal. Any ideas?

 

Thanks

[Fairtax4me]

Sounds like the idle control motor might be gummed up and is sticking. A good cleaning should help that.

 

Theres a hose that runs from the idle control valve, which is mounted to the backside of the intake manifold on the passenger side, to the bottom of the intake tube. Pop that hose off the intake (easier said than done), wrap a piece of duct tape around the opening on the intake tube to keep it from sucking in air, start the engine and block the throttle open slightly so the engine speed is up around 1500 rpm. This will help prevent the engine from stalling while you pour cleaner down the hose that goes to the IAC. You can either use Seafoam, or a spray can of Intake system/throttle body cleaner.

Seafoam: Slowly (over the course of a minute or so) pour about half of the can into the hose.

With a spray cleaner, just press the button and shoot the cleaner in.

If the engine RPM gets too low or stalls, stop adding cleaner and let it smooth out for a second. Then you can start pouring/spraying again.

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And in the event that does not work you can remove it and spray a whole can of carb cleaner in the IAC That cured my idle dip on a warm engine.. No more Start > 1,000> 400>1000> 650 rpms now when warm

 

Might of been overkill...

 

If do remove the IAC remember to get a new gasket!