high idle when cold outside

[rustest86]

my problem is exactly that when its cold outside it idles high, when its above 80* it idles fine. weird as can be, i have fought this 2 winters in a row and never found out the cause. its time to fix it. we just had our first cold front come through, lows in the 40's and highs in the 60's. this may get kinda lengthy.

all summer long car idles fine even idles up when the ac is turned on, no stumbling or anything. runs fine. every winter for the past 2 years it always idles 2200-1500 rpm constantly. like a consistant cold start and it can't warm up. but its about 180*-185* sometime a bit higher. no boost leaks or anything, because say right now it would warm up itll idle fine. ive tried cleaning the iacv, i didnt pull it, but it didnt help. tps is fine, cas is fine, no check engine light, and ive tried pulling codes but it wont even show me a code 55. . the car runs perfect other than the high idle.

now heres something else, say i go drive around, the engines up to temp, but the idles around 1500rpm. if i shut the car off for a few minutes and start it backup itll idle 800rpm, untill i touch the throttle, then itll idle back up to 2200-1500rpm.

my setupredtop SR rebuilt 2 years agogreddy td05h-18g 11psifmic, hks bov open atmosphereq45 mafcometic head gasket with arp studsgreddy emanage bluegreddy rocker stoppersarp rod boltsand everything else on the motor is pretty much stock.

and i will bring this up again, if where to warm up outside it would idle perfectly. i am completely and utterly stumped. this is way more a anoyance than a drivability issue though.

please help, i can usually figure this stuff out with research but i cant find anyone who has had the same exact problem

[youngun21a]

Temp Sensor Maybe

[the converted]

You don't have the coolant lines to the throttle body and IACV hooked up do you?

[rustest86]

sorry i didnt list that but new as of july.

and yes all the coolant lines are hooked up

[the converted]

Strange. When the engine has warmed up and is idling high, try unpluggin the IACV and see what happens. About the only other thing I could think of possibly being a problem is the thermostat.

[rustest86]

ill let you know on that when i get home. im also gonna say on the iacv that the idle speed adjustment screw does nothing for the idle at all, warm or cold outside, thats somthing that has just started when i changed the cas a few months ago and was and still am having problems setting the timming properly. thermostat seems fine as i can see temp changes with the gage and my fans kick on.

[rustest86]

ok when i unplug the iacv it doesnt change anything. i even tried racing the engine a few times and still nothing. im thinking the valve is stuck.

[the converted]

There are two separate valves on the IACV, the electronic one that gums up and a mechanical vlave that just works off temp. I'm starting to point fingers more at the thermostat on this one.

[rustest86]

well i installed a new thermostat and it does the exact same thing as before. im thinking the iacv is stuck or cant close enough to idle it down. whats bad is that it got colder here, and its idling faster now like 2500 now.

[rustest86]

ok another thing noted, i noticed that one of the coollant lines to the IACV is kinda pinched, not completely but restricted for sure. im gonna address that tomarrow and see what happens. i did ajust my fan controller a little bit today to let it run a tad bit hotter and that seemed to help out.

but the idle screw still does nothing

on a side note i got my tomie 256* exhaust cam installed today........... well worth the $90 i spent on it.