Geezy

i dunno if this is normal for any boosted motor coming off boost. i have an sr.
after cruising speed in gear, rolling into neutral coming to a light, the car's idle will drop to 400-500 rpm below a normal of 700-800. until i get to a full stop, it will go back to 7-800 rpm.

could there be a boost or vacumm leak?

tips on where to start looking for the problem??

FaLKoN240

That's the sound of a vacuum leak.

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Geezy

ok. thats one.
i'll start checking all my vacuum lines.
any other ideas?

Gription

That doesn't sound like a vacuum leak to me. Usually if you have a vacuum leak your idle would be higher... thats what I've always found to happen.

Are you running a bov? If so what kind, and is it on your hot or cold pipe? If you are running a bov on your hot pipe and you are running it vented, it's very common for your rpm's to drop really low like that.
If you don't have a bov, then you have to have a boost leak somewhere. Did it just start doing it randomly or has it does this since you got it running??

Ceepo

My car does the same thing, i know its not a vacuum leak on my car, imho i think that it is the draw of power to the tail lights causing a drop in voltage and the alternator takes a second to makeup for this loss of voltage...

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Geezy

yes i am running a HKS BOV on my hot pipe. and its been like that since i got it running.
another thing i discovered is that my dash lights will dim at the same time. but ever so slightly, you can barely notice it, but it caught my attention. and it dims at both times whether or not if i step on the brakes.

is it the alternator like ceepo says??

Gription

Yeah man its just your blow off valve. I have the same setup, and I know many others who do and have the same issue as well. Its something to do with the distance of the bov from the throttle body and the maf that makes it so the air that is vented can't be compensated enough by the MAF so it has to kind of play "catch up" to get back to normal idle speed.

There are a few fixes however. You can recirculate it to your intake pipe which apparently works 100% of the time, move the bov to your cold pipe near the throttle body (not sure why this fixes it, something to do with the throttle body being able to pick up the air faster or something??), or... just don't run a bov and call it a day haha. The reason your lights are dimming is just from the loss of power. Have you ever noticed how your lights get brighter when you rev the motor? Same thing here, just opposite. Doesn't have anything to do with your charging system.

RickJames503

+1, just like everyone is saying it's caused from your BOV being on your cold pipe, some Boost controllers have setting's to some what solve the problem..... if your running a boost controller look through your hand book. but like everyone has stated it's totally normal if your BOV is on the cold pipe to have this problem

Geezy

ok.
so i assume this is all normal now.

Tom25666

msglngth

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Geezy

lol. i noticed that too.
gg.

zylvia213

I have the same problem and im trying to get around to fixing by recirculating my Blitz BOV. I have also been told by a couple of peeps i can be the IACV or how ever you say it lol .

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!Zar!

Also check your intake pipe if you are running the stock one. They tend to get old and brittle. I have the same issue as op and my bov is recirculated. But I don't really care being as how it doesn't affect me much.

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Geezy

alright. so im not all jacked up.