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Discussion Starter · #1 ·
When it's cold outside and I start my WRX it idles at about 1,500 RPM. If I let it warm up for a couple minutes the RPMs drop down to a normal idle (900 or so).

Ever since I got my car, whenever it was idling at 1,500 RPM after a cold start, the RPMs waiver up and down maybe 150 RPM. You really didn't notice it when the car was stock, but now that my exhaust is pretty loud it sounds a bit funny. Once the idle speed drops down to normal (after warming up), the idle is rock solid.

Does anyone's WRX do this?

Mods:

TurboXS catless up-pipe
ScoobySport catless down-pipe
ScoobySport catless center section
Borla cat-back
De-snorkeled intake
UTEC
 

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mine idles a little higher then 1500 when it's cold but its been like -15 here for the last week.
 

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SpeedRacerWRX02 said:
mine idles a little higher then 1500 when it's cold but its been like -15 here for the last week.
That's nothing. Last week my WRX started (like a lame dog) at just over 2000rpm.

Beat that you wussies!!!!! :p
 

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Well, 1800 is the most I've seen mine do, I guess 2000+ tops me.:) My question is such, since I've had the unichip (and many other mods) I have a variation in my idle about every 30 seconds. It sounds as if the engine load is increased for some reason, the engine sounds a lot louder and the lag from the turbo which normally reads -.5 bar falls to -.7 bar. I can't figure it out...any ideas? BTW it does this in all weather.
 

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Discussion Starter · #7 ·
That's what I was asking Stiles. It's not the idle speed I was pointing out, rather the fact that the RPMs increase/decrease by maybe 150 RPM every 5 seconds or so.
 

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wonder if it's the UTEC/Unichip, I don't remember it doing this stock. Oh, and mine is like 15 sec. low RPM by like 30 sec. regular. So someone else is seeing this too, hmmm....
 

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My truck ('98 ranger) does a similar thing. I don't have ANY mods :D . It will drop down and jump back up sometimes. Its eractic and kinda un-nerving, but I've grown to ignore it.
 

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Discussion Starter · #10 ·
That's another point. In my car it's not erratic at all. It's VERY consistant.

Anyway I'm not too worried about it. I was just curious if other had seen the same thing.

Thanks guys!
 

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Mine does that too. It seems to be consistent when the cooling fan turns on. Which they do about every 15 seconds when the car is up to normal operating temps. Something to look into......
 

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My car does the same thing in the morning and mine is completely stock. Some mornings are worse than others. It's got to be something slightly quirky in the stcok computer programming.
 

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Discussion Starter · #14 ·
I think I found out what it was. I read something once that said that the rear tabs in the airbox lid are a pain to get into the airbox. I went outside and checked, and sure enough my tabs were not engaged. I could lift the driver's side of the airbox lid off the airbox.

It was a real PITA to get those tabs into the airbox (bad design on Subaru's part). But now that I got them engaged, my idle doesn't fluctuate anymore.
 

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Thank you so much! This is exactly what I was looking for! Went out, saw the tabs hanging out, forced them in, and ran it for a while. after getting the car sufficently warm, I sat in a parking lot and the idle didn't vary at all for a 10 min. period! Thank you soooooo much! You rule Doc!:D :D :D :cool: :cool: :cool: ;) ;) ;)
 

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Doc said:
I think I found out what it was. I read something once that said that the rear tabs in the airbox lid are a pain to get into the airbox. I went outside and checked, and sure enough my tabs were not engaged. I could lift the driver's side of the airbox lid off the airbox.

It was a real PITA to get those tabs into the airbox (bad design on Subaru's part). But now that I got them engaged, my idle doesn't fluctuate anymore.
Dude!!! Thank you so much. I just changed my plugs and started to have this problem. I couldn't figure it out. I was trying to figure out why it only happened when the cooling fan kicked on. I ran downstairs in the parking garage just now and fixed my mistake when putting the air box back together. :) It runs SO much smoother. This summer would have sucked with it idling so badly. I hit traffic a good bit on my commute and having it stumbling would have been bad.

Sometimes it was barely noticable, the tach wouldn't show a change in rpm, but it would shake and sound like it was running rough. Othertimes it would drop to 200 rpm, then jump to 800, then start to settle back to 500-550rpm. Now it runs like new. :D
 

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my car does the same thing....ill have to go check my box in the morning
 
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