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2010 FXT Auto4
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409 Posts
Discussion Starter · #1 ·
The engine shakes at idle(~600rpms),also if you rev it will drop down in rpms below 500rpms almost stall.Also i'm getting some surging at lower rpms and slowers speeds. Are these things normal or is there a problem I sould be addressing? Thanks for your input.
 

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04 Forester X, MT
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1,039 Posts
with no CEL codes, maybe time to clean IAC valve and throttle body?
 

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2010 FXT Auto4
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409 Posts
Discussion Starter · #4 ·
No CEL codes. What is a IACV and it's location? How to clean it? Could a fuel filter cause these problems or bad fuel pump?
 

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04 Forester X, MT
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1,039 Posts
IACV = idle air control valve. Affects the idle rpms. Sits atop the throttle body where the coolant lines go in and out.

Cleaning And Reattaching The IACV (Idle Air Control Valve) - NASIOC

MMm fuel pump could be too.. my boss' Chrysler had to have his pump changed twice to fix similar symptoms.
Most (all?) Foresters don't have the IAC in the coolant system. The IAC is mounted in a similar place on the throttle body, but has a blue sticker. I think it is really the same for 98-04?

99 00-04 Impreza Legacy Forester Idle Air Control Valve : eBay Motors (item 160364684948 end time Feb-20-10 10:43:03 PST)

BTW I wouldn't pay that much for a used one.
 

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2014 Forester XT Touring CVT
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799 Posts
yes mine is doin this too... i was hopin it would go away once i cleaned the throttle body..

but on the IACV.. we have this? i didnt think we did since there were a lot of posts sayin the newer DBW models dont have this..

n now readin Woodys post.. how would you clean the IAC? or do you just have to replace it?
 

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04 Forester X, MT
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ultimately for a long lasting repair i think you have to bite the bullet and spend the big bucks to replace, but periodic cleaning of throttle body is important regardless of any problems.

i used spray carburetor cleaner on mine with gentle wiping or brushing action on the part that is inside the throttle body with the brownish gunk on it. it seemed to help a lot but then i wasn't having severe symptoms to begin with.

i picked up a known good used one for about $40 to swap out and see if it makes much difference. i have a hard time paying more than 10-15% cost of a new one for a part like this.

edit
the newer ones are DBW, not sure exactly where they started. I have seen the IAC 98-04.
 

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Ah crap.. I'm back with my 05 XS
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2010 FXT Auto4
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409 Posts
Discussion Starter · #10 ·
My 04FXT does not have one these IACV.It has a sensor similar to MAF sensor.
 

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2014 Forester XT Touring CVT
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No XT or dbw vehicle has an IACV. It's all computer controlled now.
ok.. so, what other than a dirty throttle body or vacuum leak can cause a minor rough idle n surging? could spark plugs do it? cause im due for a change in ~500 miles haha

ps.. sorry for jackin this thread
 
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