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Guest Message by DevFuse

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Idle speed lowers w/brake applied

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5 replies to this topic

#1 Holmes


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Posted 30 December 2003 - 03:54 PM

I noticed that my idle drops ever so slightly when at a stop when I apply brake. Raises when I let off on brake. Just wondering if this is normal.

#2 TheSubaruJunkie



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Posted 30 December 2003 - 04:00 PM

Its done it on every subaru ive owned.


#3 bushbasher


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Posted 30 December 2003 - 04:10 PM

the sube, honda, and the caravan all do it. It has to do with the vacuum boost on the brakes

#4 GeneralDisorder


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Posted 30 December 2003 - 04:17 PM

Your brake booster likely has a vacuum leak when you apply the brake. If it's not a large leak, everything will still work fine. A correct booster will cause a slight change in idle if you pump the brakes, but if you hold them in it shouldn't technically change the idle like your describing. I wouldn't worry about it unless it's severe.


#5 Holmes


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Posted 30 December 2003 - 05:02 PM

Thanks for the replies. :D

#6 myossfeece


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Posted 30 December 2003 - 05:52 PM

yeah it sounds like normal activity there. when you apply the brakes, the idle will drop slightly beacuse the vacuum booster kicks in and acts kinda like a slight vacuum leak. At least to the motor, because it's trying to replenish the vacuum lost from the booster on the brakes. my 2 sense n e way. I wouldn't lose any sleep over it.

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