cars been doing it for awhile. never thought it was a big deal but its kinda weird
ill be driving and coming to a stop. ill throw the car in neutral and brake until the car stops. the rpm will drop to like 400 and then jump back up to 1000 and then finally settle at about 650.
i remember people saying this had something to do with BOVs. that would make sense if my bov was a little open when i stopped (and it is)
but im not sure if thats the problem. (greddy type S)
and i still have stock spark plugs
no too worried about this,
just wondering why

 

I notice this happens with my lightweight flywheel.. but not as drastic.

If I'm coasting to a stock in neutral, it'll go from like 500rpm to 800rpm until I come to a complete stop.

I also know that small vacuum leaks can cause the RPM to go up and down.. check that maybe?

 

I have this problem too. I really don't think I have a vac leak because I have hose clamps on everything. and this just started happening, but I had my car tuned and it runs ok but when it comes to a stop the rpms rev then hit like 400 and the car dies sometimes... I notice that the afr is going from 13-15 but other times it idles fine....so I have no idea what this is

 

The car shouldn't be stalling..

I would definitely do a boost leak test to see if you have a leak. Just because you have hose clamps doesn't necessarily mean there's no leaks.

 

the bov would show rich condition on afr gauge does it? if it does then it's that.

if it doesnt then it's the fuel trims, our cars are _____es with fuel trims.

cel? yea, then it's def fuel trims

no, then it's probably the BOV, you'll get a cel later.

i had this problem a long time ago, it was the factory ecu correcting the messed up fuel trims whenever i stopped and hte BOV let out air. tuning was the main reason though...because it was never professionally tuned i could never really get the fuel trims correct.

 

do you have a cel?

 

650 is pretty low though matt, i idle at 750-800

 

I get a cel 0172 which is running rich, but my afrs are ok for some reason. and it doesn't do it all the time and my cel doesnt come on all the time. like when I first start up the car it idles fine but say I get off the interstate after just cruising then get stuck at a red light my rpms go crazy and it goes from around 1200 down to 400 then back up and sometimes it stays running and other times it stalls

 

BOV, is it recirced?

 

pm sent

 

that bov is notorious for stalling the car, recirc it

 

how do I do that or has it been posted somewhere?

 

i'll explain it to you when i get out of school, theres the make a fitting or the buy a fitting route.

i made one.

 

Depends on what BOV you have.. if it's an HKS SSQ then you need to buy the adapter - it usually comes with a 1" dia fitting. Then you'll need to buy a 1" dia radiator hose and have a shop fab a port on your intake to turbo (after MAF).

 

This is common on a 100% stock tC as well. Nothing to cause alarm

 

Ahh.. good to know. And NOT good to know of my mis-spelling... ^^ Stock = Stop

 

I read what you mean, not what you type.

 

Mine did it stock, then did it when I was boosted.. I noticed it does it more when it's blazing hot outside.

 

I am kinda overwhelmed with stuff right now....my turbo problems, my interior being ripped out, no bumpers, fenders, or hood on my car, my body kit trying to be put on plus trying to finish my retro fit...all by Oct 2....so many things so little time

 

so the reasons are

BOV

bad tuning?

in my case probably a combo