16V cold idle Issues and more

[fixkick]

hello new guy and welcome.!
good choice upgrade to any Sammi
the IAC under the throttle body dictates speed of idle drop from cold, and of course #1 is the cooling thermostat most get fully hot fast..
hot ISC pinch ,that is wrong results (done right you did), you've got air leaks.
if hot 180F coolant and the 02 sensors is swinging, then there is an air leak , so block the IAC square port to prove it leaks,
other causes?
or someone unscrewed the idle bleed screw. on top of TB (under black plastic cap)
http://www.fixkick.com/fresh-air/Slide_S...ge_25.html
or throttle cable is too tight holding open the throttle. (or if A/T tranny the kick down cable too tight) im sure you dont have cruise cables.

i think the evap VSV is closed at idle, it opens only moving car, like EGR VSV. id be worried that this thing leaks at idle.

i think the IAC is bad, so block its small rectangle port, use clay or duct tape, the latter , might suck in easy, so clean the bore well with carb cleaner so the tape sticks good.
I like the clay block trick, because i can pack it tight in to that hole (slot)seen below.
my guess, is this
the ISC is closed, hot, because the ECU sees this huge air leak (rpm ) and shuts it down.
the ISC is supposed to be at 50% dutycycle 800rpm hot. yours is NOT. that is for sure, you proved that.
my guess, is the IAC is stuck open and then PO, cranked in on the idle bleed screw to hit 800. this is wrong way to set idle.

one more leak , is some one turned the never touch screw on the throttle valve stop,. the TV must be closed 99.9% in fact its so closed water will not pass thru, off car.
TV closed 99.9% (no touch screw)
IAC closed 100% hot. (test it)
ISC tuned with bleed so ISC is about in the 50% middle of its range. most times if there are no leaks, setting bleed to 800 RPM hot , does in fact let the ISC work in mid range.(correct)
the factory calibrates the ISC for that, to happen. (see side screw on iSC)




my 97 had a stuck IAC (thermal) and did same deal. i found a used one that worked, a hole Throttle body. in fact.

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btw,. this system air density using the MAF works like this. HOT engine only.
all illegal (un-metered) air cause engine to go leak, (closed loop functions can correct small leaks but not big leaks which cause lean and too low RPM)
The ISC will correct it this until about 400rpm worth of leaks are corrected until the ISC closes 100% then hold there.

Legal air leaks all cause normal AFR,. not ever lean, and all cause fast RPM hot. (isc will in fact try to correct all RPM errors, no matter what)
this list is short for (metered legal air)
1: TV (its closed )
2: ISC, its 1/2 open (50% duty modulation) electric
3: iAC thermo valve ,its closed. so is not a factor here. unless its NOT?

take off the front air tube from TB lips and pack that port in clay tight,
the put back the air pipe.
then attempt to set the Bleed to 800 rpm hot. im hoping you can.
4: bleed its set to 800 RPM this bleed rate assures the ISC has lots of range.

all hose leaks are illegal air hot, and drops RPM due to lean state, and ISC will try to correct it.
there is tiny PCV leak
no EGR leaks (all are bad, unless moving fast )
No VSV valves that leak. at hot idle. if the TPS idle switch is wrong, both VSV can get confused, (might)

i think the 16v system is easier to find leaks, than the 8v, the 8v has many ways they can leak inside, very odd ways.
The 16v has this very simple TB, just like all modern cars, (less electric motor on side, throttle by wire)