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Discussion Starter · #1 ·
Interesting problem popped up on my 99 Forester as I drove to work today. When first started, the idle was noticeably low and upon warming and coming to stop, engine idled to near zero rpm and died.

I'm thinking idle air control valve has failed and inadequate idle air through valve. Anyone else had this problem or suggest another possibility?

It should be interesting to repair, since I'm currently 1-armed due to shoulder surgery for torn rotator cuff. My wife may have to help,... oh Lord!

good luck
 

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Premium Member
2014 Impreza Ltd CVT
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3,319 Posts
99 was a MAF motor. Be certain none of the hoses by the airbox or throttle body came loose or fell off. Common problem especially after any under hood service.
 

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04 Forester X, MT
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1,039 Posts
sometimes you can clean an IAC valve and it work better if it is a little sticky.

mileage?

a new one is kinda pricey :icon_frown:

if you take out the IAC:
the screws are a little soft and might be stuck well, so be careful to have bit that fits well. you have to push into the head while turning to prevent "stripping" the phillips recess.
 

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Premium Member
2002 Forester EJ25 4EAT 2011 Forester FB25 4EAT 2021 Forester FB25 CVT
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39 Posts
What about the Air/Fuel sensor?..................have you had it replaced lately?................They usually fail in cold weather months...............check that first.
 

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Discussion Starter · #5 ·
After sitting all day Tuesday, the car restarted and idled perfectly as I drove away from office on a cold (45F) day in Houston. Alt light and Brake lights came on briefly, and I glanced at my voltage monitor. It had gone to 15+V, a level I've never seen before.

My first thought was I've left a ground lead loose somewhere after my recent HG repairs. I got my wife to brace the hood, while I held up hood w/ my good right arm. I checked grounds and found none loose that I could find.

I had some problems w/ the plastic latch (may have damaged) on the alternator connector and I never could get a firm "click" on reinstalling plug.

After driving again today, neither idle or Alt+Brake light problem have recurred.

thanks
 

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The Modfather
2019 Impreza 5dr Sport - Manual
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8,071 Posts
99 was a MAF motor. Be certain none of the hoses by the airbox or throttle body came loose or fell off. Common problem especially after any under hood service.
Not only was the 99 and MAF style it also had a recall for that year's MAF as they were prone to going bad. (thin film type VS hot wire) the good news is they are relatively cheap. Are you the original owner? Do you know if it was ever changed?

Have a look here:

http://www.scoobymods.com/maf_replacement_air_flow-t414.html?t=414

Scroll down to my update.

My other thought was check the wires up at the coil pack for corrosion.
 

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Discussion Starter · #8 ·
Thanks, I'll check the alternator output insulator.

I'm not original owner and purchased w/ 85K miles, and now at 215K. It runs like a top other than described problem.

Idle problem has not returned since Tuesday morning episode. Alt+Brake has not returned since Tuesday afternoon.

Thanks
 
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