('03-'05) idle troubles - Subaru Forester Owners Forum
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post #1 of 6 (permalink) Old 11-07-2012, 10:49 PM Thread Starter
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Join Date: Jan 2011
Location: melbourne australia
Posts: 25
Car Year: 2000
Car Model: forester
Feedback Score: 0 reviews
idle troubles

so ive been having some idle troubles,
o2 was bad so replaced it and fixed exhaust leak
still however sometimes when i go to start it
it starts then stalls straight away, or idles really low or idles at 2000rpm -.-

spark plugs are due have replaced the passenger side as they were easy to get to today.
I have 2 amps one powering hte sub the other the front speakers i also noted that my main ground line from the engine is a aqua colour will be upgrading this soon but in the mean time i added another ground from the battery to the body

i have hids but the idle issue still occurs when there not on.
when i turn the a/c off the revs raise about 150rpm and when i turn my stereo off the idle increases very minimally

the other things im thinking might be the issue

PCV valve?
spark plug leads?
the drivers side spark plugs?

i should note that theres no CEL on and i have checked it with the obd reader.

after changing the 2 plugs today it seems a bit calmer
idles around 500rpm except after moving if i put it into neutral or i put the clutch in before i take off again the revs rise to 1500 then drop slowly
does this sound like a neutral switch?

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post #2 of 6 (permalink) Old 11-07-2012, 11:07 PM Thread Starter
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Join Date: Jan 2011
Location: melbourne australia
Posts: 25
Car Year: 2000
Car Model: forester
Feedback Score: 0 reviews
oh i also cleaned the IACV ive done 180k kms should it be replaced?

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post #3 of 6 (permalink) Old 11-19-2012, 08:30 PM Thread Starter
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Location: melbourne australia
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Car Year: 2000
Car Model: forester
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post #4 of 6 (permalink) Old 11-19-2012, 09:15 PM
Taking a Walk in the Outback
Join Date: Jul 2012
Location: Hickagain.... (Mi)
Posts: 917
Car Year: '03
Car Model: Fozzy
Transmission: Eat A Taco
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finish the plugs and wires first...

When did the problem start, after you did something or just out of the blue...
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post #5 of 6 (permalink) Old 11-20-2012, 07:54 AM
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Location: Ohio
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Car Year: 2000
Car Model: Forester S
Transmission: AT
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Temporarily disconnect the amps. See if issue goes away.
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post #6 of 6 (permalink) Old 11-25-2012, 04:38 PM
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Join Date: Oct 2012
Location: Vancouver
Posts: 60
Car Year: 2003
Car Model: Mercedes C320
Transmission: Manual
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This was my tune up i performed on a rough running forester xs with a rough idle, it now runs like a dream!

  • One bottle of Seafoam in the fuel tank, with a full tank of petrol.
  • One can of Seafoam spray, used through the throttle body, used half then blew the smoke show then gave the car a run and then i did the process again with the remaining half.
  • One third of a bottle of Seafoam in the oil, and ran it for 100km, my oil got noticeably thicker with all the crap it was taking out of the engine so be careful.
  • Castrol 5w30 Synthetic Edge oil change ( Sounds and runs smoother, is no longer burning excessive oil, better mpg, )
  • NGK Iridium IX sparkplugs ( My old plugs were well worn and the new ones made a massive difference )
  • NGK plug leads fitted with dielectric grease ( Made the car idle much more smoothly )
  • New PCV valve ( Not burning as much oil and the car idles smoother )
  • K&N Airfilter and custom DIY ganzflow style CAI keeping the torque box in place ( The old filter was dirty, but wow this made a noticeable performance difference )
  • New grounding kit fitted with dielectric grease to compliment the old corroded OEM grounding kit. (smoother idle, internal and external lights no longer dim when other electrical things in the car turn on anymore, perhaps a marginal increase in MPG)
  • New Front upflow oxygen sensor, from what i understand these things deteriorate over time even if you don't get a CEL and by the looks of other things in the car i made the call to replace it. The result was much improved fuel economy.
  • New Fuel filter, i tried blowing through the old one and there was twice as much air resistance than the new one so deffo worth changing out.
  • Throttle body cleaning, removed the throttle body and replace gasket. (improved idle, the clean helped and the gasket was shot and causing a possible tiny air leak)

Anyways this is what i did and it cost me in the region of $400 for all parts and fluids etc, i got nearly everything on ebay as part prices in Canada suck, elbow grease is free though...

Also I know its contrary to a lot of members beliefs but i have been starting to use premium fuel and the car no longer pings/knocks at low revs. the owners manual said at least octane 87 and Ive been using 91. For the difference of 5 cents per liter i am happy and the performance IS noticeable.

You also want to check all of your Vacuum lines, any leaks will cause a bad idle. I had a bad throttle body gasket that happened to be causing mine, but check all the lines too. If you spray carb cleaner at the vaccum lines and gaskets you can tell you have a leak if the engine note changes as its inhaling the carb cleaner from somewhere. Its not an exact science but it works.

Also if you mist water at your ignition coil when the engine is running and the revs change, you know your ignition coil is buggered.

Want more power from a Fozzie XS? Just sell it

Last edited by Jarvace; 11-25-2012 at 04:53 PM.
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