Kizashi Club

car has been running perfect, yesterday, started it hot and got a very rough idle, almost stalled and brake pedal got harder (not complete loss of power, but noticeably harder) sounds like a vacuum leak to me, but can find one anywhere, line from brake booster to intake is perfect, recently cleaned throttle body and maf, installed new plugs, could use some ideas where to start troubleshooting.....searched forum and couldn't find anything related to both problems at the same time

forgot to mention, pulled line off of brake booster right after shutdown, and it does have vacuum, not a lot, but a quick hiss when I pulled it.....

Try pinching the pcv hose off while at an idle using a pair of needle nose pliers . If pcv is stuck open it could give you these symptoms. pcv mounted in firewall side of valve cover between cyl 2 and 3

unfortunately old tech, no change at all, even tried both hoses to make sure....

When was the last time you've brake flush? Sounds like master brake booster is on its way out, have that thoroughly check up otherwise.

I haven't flushed it, just replace pads and bled lines (since I have owned it) would a bad booster cause the idle problem though?

Symptoms of booster leaks are higher than expected fuel consumption , cold start and rough idle issues, if you know what to listen for, you can actually hear the booster leaking vacuum from under the dash. It may sound like a fan running under the dash and may change in volume as you apply the brakes while stopped or the hissing noise may diminish when accelerating normally from a stop.

Try pinching off hose to vac booster. If there is a change then G13b has nailed it. If still no change then maybe fuel mixture is way off caused by debris on maf . Remove and spray with carb cleaner. Another possibility is vvti actuator stuck. I have yet to see this problem on a Kizashi but plenty of times on Toyota, lightly tap around mounting bolt with engine running and listen for change . One last area is canister purge control that possibly is stuck open.

if your car is CVT check CVT oil.Contaminated CVT oil may also cause engine rough idle specially in hot weather.

I actually have time today to get to it today, thanks for the replies, did clean the maf already, cvt fluid was changed beginning of summer...will try the rest and get back