Cold idle when hot?

[fixkick]

good code 12 (happy ecu) its not in limphome, nor backup mode, good.
i see no missing major parts., all look stock
no idea at all what that silver object above and rear of Valve cover.?
sure market 24 is Australia.

so test one (TEST 1)
when at 1500
open hood and see TB see throttle top in photo push firmly the crank to your left, this closes the throttle 100 % if it has gunk inside.
then if that does not lower idle (agood sign), we then...
1500 rpm still.... hot idle wrong.

TEST #2:
un plug the isc connector. engine will stall or run super slow rpm 400 or less.
if not you have a leak,
(on a hot engine here are only 2 air paths, isc and bleed) no others, with isc closed, only the bleed path is open, (if at all) and engine stalls.
one exception is some 'BAD GUY" unscrewed the bleed screw 10 turns, to fully open.'
this screw is idle duty cycle setting and not idle speed. (ECU controls speed only)
when you see 1500 rpm that means the ECU lost control of idle, a fact.

just 2 tests, and we can reduce the list of possible greatly.
CAN YOU DO THOSE?
JUST 2 TESTS.?

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I SHRUNK your photo again,.

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TO FIND FAST IDLE, TESTs MUST BE DONE.
guessing is hopeless ,
on a good 16v, there are only 2 air source hot, this is a fact. (BUT NOT YOUR CAR)

if test 1 passes
and test 2 fails, I'm sure it will
but if test 2 fails, we then do test 3

TEST 3 is.
PINCH TEST is #3
pinch the ISC air line (2 are hot water) 1 is air, pinch air hose. (keep isc unplugged)

if RPM falls to 400 now or stalls, that means the ISC is bad.. (stuck open , clean it) test it. its leaking air way BAD.
if RPM screams pinched, this means the IAC is stuck open. (if lucky and not H3LL mode and end of this page)
see this logic path >? note how i make zero assumptions, as most of them are dead ends. wits ends.

id say engine i ok. if it has full power, ill guess yes its ok.

test 4: is next,

the IAC test. (we first make sure it fully hot, some way, or prove the water tubes to it are not blocked, end to end ever inch free flowing water)
IAC is 100% a thermal acting device.
the IAC has 2 hoses. both can block, end to end, even the source to said hose can block, we back flush all these parts. to test them for flow.
The IAC itself can water path clog, and make it fail.
the ISC has a water path if blocked can block water to the IAC, because they are in SERIES.
see on my annotated drawing here.
http://www.fixkick.com/Cooling-engine/16...aths2w.JPG

those are all pretty simple tests, so far almost no tools. but owning and IR pyro gun saves huge labor. for sure testing radiator cores.>>....

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(point and shoot, ah 170f t0 195f here)
bad guy #2, failure seems like every day we get this guy. (who are these persons....,? )

my page
called screwed again, covers this lil' horror , someone played with the TV stop screw.... again...
http://www.fixkick.com/IDLE-AIR/screwed-again.html

btw the bleed duty screw is here. (fiy here it is)
http://www.fixkick.com/IDLE-AIR/16V-Tbody1w.jpg

back to screwed again...
The TV has and idle stop screw that must never be touched. (same with ISC calibration screw)
if found molested, ( many unknowing mechanics, turn it to raise idle speed, (like carbs of old) but is bad news that. all bad news.
The fix, covered on my page on topic. is. (this does work)
i set them to 0.0005" gap, or 0.0127 (.0130mm) using feeler that size, note the leading zero there, in front of 1. NO TYPO.
this gap is about size of mums, kitchen aluminum foil , cheap box size, super thin )<<< poor mans feeler gauge it is.

the ECU can not deal with huge errors, or added (stacked) up.
bleed screw fiddled open. (this is ok to play with)
TV gunked up, blocking proper snappy closures......
TV stop screw, hell. done by Mr. bad guy..... simple fix.
ISC leaking, clean it, test it with 12vdc battery, 12v=open ,0v = closed, its spring that closes it, and mag, field opens it.
IAC leaking , (i have a test, ask) (i use a clay tests) removing the 16v IAC can be near impossible, i dont try, i test it with TB as ONE !
ISC water path blocked.


what is happening when you see 1500 on the clock hot. parked.
1: ECU has lost control of idle, is a fact.
2: why we don't know, yet, only tests prove why.
3: personally i pinch the ISC hose, like wild man,. bam, pinched. (rpm drops, only a tad,? or , rpm to 400 stalls) ???????????
if rpm falls super low and or stalls, then ISC is stuck open., (so much is learned here in 5min work , no?)
if rpm only drops a bit, say 1500 to 1000>? then you have IAC stuck open or TV stop screw molestation, or bleed was unscrewed 10 turns.
i screw in the bleed, and rpm drops a tad. oops, we do have some leaks for sure.
Keep in mind, I have no idea from where. Im only checking legal paths there, the 4 legal paths.


now the bad news. what i call H3LL MODE:
on some engine,(seems common on old engines) there are 2 problems. that in a sick sick fate of bad luck , help each other. and that is what?
Not saying this is it.

1: engine in limphome or fuel pressure at 60 PSI (FPR fails hard, on all these old cars , many now)
and it's super rich running, ECU can NOT control fuel mix right, now..... ECU can not know fuel pressure is 2x normal, its just LOST.
then
you get and illegal vacuum leak, this illegal , unmetered air supply ADDS to the illegal fuel flowing and engine races.
this is A DUAL failure. and does happen.
so keep and open mind, and is why i check the easy stuff first.


keep in mine good 16v go lean , with vacuum leaks.
and run slower. not faster
but in H3LL mode, the opposite is true.
on a good engine you can create a vacuum leak (small) and ecu corrects the mix, using closed loop.,
if you add more vacuum leaks the ecu looses control and slows, RPM.
on rich engine, the opposite happens.