coolant temp sensor
throttle position sensor
stupid vacuum leak
fuel pump being stupid depending on how hot it is outside.
the tune doing something stupid depending on how hot it is outside.

 

ok so i looked around in my bay this morning after i started my car up to see if i had any vaccum leaks or anything like that. i noticed that there was a constant flow of air coming out of the BOV. which makes sense because the turbo is still spinning at idle a little bit and the throttle plate is closed so that is the only place for that air to go. makes sense to me. so i take off the vaccum line to the BOV and cap it off with my finger. the miss firing stops and it stops running super rich. the idle jumps up to 1,8-2,000 rpms for about 20 seconds, then drops to 1,200~, then it keeps dropping as it warms up til it reaches 800~ rpms. then ill put the vaccum line back on the BOV and it will run fine. im running a pull-through MAFS setup so it makes sense why it would run rich like that but what confuses me is that why it wouldnt be doing it the last 16,000 miles my KA has been boosted.



another weird thing i noticed is that once i start driving it, the BOV seems to be "stuck" open so to speak until i hit the full 7psi. it just wooshes air out of the bov, then once it reachs 7 psi, then it will seat properly. it only does this when its the first start in the morning or first start of the afternoon after work.

 

If you're running an hks ssqv, which it sounds like you are. You might need to grease the sliding portion behind the diaphragm or buy a better bov.

 

I was running a dsm bov. it did what yours did, spewed at idle and at low rpms it ran like ass, horible mpg

took it out and ran no bov, went up to about 28 mpg, pulled hard. Idk shit about the ssqv, but ^ the post above me seems correct.

 

BOV is broken. Are you using the 2g plastic one or the 1g metal one? If its metal is it crushed? Its possible it was over-crushed as well..

 

well... i let my car cool down all the way. took off the vaccum line for the BOV, capped it, fired er' up. bam. car runs fine. idles at 1,1-200 rpms til it warms up but no misfiring or running stupid rich. looks like im gettin a new BOV lol. it still runs a tad rich but its always done that. now off to advance to get another set of plugs lol



EDIT: oh and yes im running the HKS SQQV. the black "limited edition" one.