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Idle Issues
#1
Can someone give me idea on why my idle is screwy. I noticed that it started last week after driving the interstate back and forth from work I have a 91 kick 1.6 8v 5 sp. 2 door. Most days it drives fine with the idle @ 800 rpm. Then off and on thruout the week it will idle 1200rpms. I have replaced many parts within the last 2 yrs. EGI, TPS, MAP, Batt, Alt, Timing Belt, Fuel Pump, Fuel Regulator. Ran fine after replacing all these parts.

1991 Sidekick TBI 1.6 8v 5 spd 2 door
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#2
8v is TBI , and all large illegal air leaks cause bad idle.
1200, A.C on, causes fast hot idle as does the P/S overload switch sticking closed. (ECU fast idle pins, set true active)
pure random. hot.
ISC sticking. (clean it)
i dont see how gaskets and seals can leak randomly, but is possible (rare)

when does the 1200 happen, hot engine, but when, fails to drop 800 hot. or pure random 1200, when was 800 say at every traffic light then next light its 1200? like that.
im sure the engine is really hot 180F. normal.
http://www.fixkick.com
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#3
(04-17-2014, 10:16 PM)fixkick Wrote: 8v is TBI , and all large illegal air leaks cause bad idle.
1200, A.C on, causes fast hot idle as does the P/S overload switch sticking closed. (ECU fast idle pins, set true active)
pure random. hot.
ISC sticking. (clean it)
i dont see how gaskets and seals can leak randomly, but is possible (rare)

when does the 1200 happen, hot engine, but when, fails to drop 800 hot. or pure random 1200, when was 800 say at every traffic light then next light its 1200? like that.
im sure the engine is really hot 180F. normal.

Vaccum tests came out good, no air leaks

With No accessories on, will idle at 800, will almost die at traffic stops, but will catch itself and come back up. While cold or hot (with no accessories on) it[/color] will run at 800 most days, But on some days in the afternoon pure random (weather cold or warm) will run 1200 the whole time.

ISC is new

EGR is new

OX sensor new

Fuel pump and regulator new

TPS new
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#4
the CEL is out at 1200 rpm) i bet yes.

with the car hot. (180F coolant , never below 150F or all is lost) a hot engine
1: RPM is 800, (ecu does that magic #) you turn on all accessories on the car, and idle may drop a second and return to 800.
does it do that, on good days.? yes, good, that means the ISC is working (when is say that , that means the system not just the new isv valve.. see, the software must work too.....!!!)
iSC is a system not just a single part.
on days with 1200.
2: i get out of car, open hood, and press on the throttle shaft bell crank the Throttle valve, and force it closed. did idle drop now? bingo
i dont drop (or DANG me. the dash pot is pushing on my throttle !, Dang me 2, the Dash pot ISC valve is cracked !
3: i then pinch the ISC air hose, (the cool hose is air) pinch the cool hose. idle drops to 400 or stalls or near stalls. bingo good , no? its way higher, ?
this tells me who or what is causing too high idle, in fact is AIR leaks, but who is it.
A: the ECU doing that.
B: air leaks?
C: ISC sticking (not yours its new, stated here for accuracy )

i focus on air. where is that silly air leak?

lets say i pinch the ISC air and idle drops to 900. (bad)
i can see now , that there IS a leak.
so i then pinch every air hose (vucuum lines (brake booster too) to find which hose leaks,
ISC hose see it here?
http://www.fixkick.com/TBI-1w.jpg


see hoses here, for function, my right drawing shows 91 and up 8v
http://www.fixkick.com/engine/8v/vacuum%...age_2.html

cant be 3speed modulator vac. line leaks because its m/t but last month one guy had a A/T intake with jury rigged modulator port, that sucked air hot. so.... only reality works, eyes on.
seen here
http://www.fixkick.com/engine/8v/vacuum%...age_6.html

the key to find the air leak
is to block all paths , and sources, 1 by one, and you will find where it leaks, and then who. for sure.
the engine will not run with no air supply , that fact is the method of discovery
what if every other time you run car the IAC fails to close.? in the base of the TB?
that would be hard to find.
who would that manifest itself.?
easy, (kinda) you block all air sources and engine screams.. still, TV closed, ISC pinched, all air vacuum lines pinched (never MAP, only inspect the map hose 22,21 carefully)
and it screams. still, you got leaks.
see all hoses here
http://www.fixkick.com/sensors/8v-sensors.JPG
you the use my bad idle pages direction on how to defeat the IAC.
there is only one way,. and that is the ISC side plate (this is a wits end test as the screws there can be hard to remove)
i pack the port with clay. TBI 8v throttle bodies are a PITA to work on. lots of paths inside to leak where no person can reach. but I do and can.

ill stop here, my posts will assume all parts on the car are bad. (mine were) and then do tests to find what works and what dont.
techs are 100% suspicious of parts. or get no where, testing. 0 assumptions work. best. (every time too)
assuming new parts are good, is deep pit that leads to hell.
avoid that and win big time. (mil training)


so do my 3 tests. above.
this is all seems complex but those 3 tests. tell you what part of the system is failing. easy.
especially the 1200 rpm tests. (real failure tests)

like i said, on guy here had all hoses blocked and engine screamed ,even with clay packed in side the IAC.
the TB was cracked inside, where no one can get to. even hand held over air horn the engine ran, (a small horror that)
the hardest of all failures. we hand to prove it by process of elimination. all new gaskets too. (and other lengthy tests)
im sure yours wont be like that.

but lets find the basic case.
Is the ISC doing it.?
IS the IAC doing it?
or is there something else leaking.?

there are only 3 normal paths, ISC, IAC, and TV. (and bleed valve which you can close to , CW screwed to stops)
if engine races with all those blocked, the induction is BREACHED. why?, because there is no air, flowing at all now. (the test )


here is the IAC trick
test 42 here.
http://www.fixkick.com/fresh-air/fresh-air.html

54 steps to find the leak, i never do all 54, I check the 3 normal paths then do the others as needed. IAC, ISC, TV, if closed, and races, its breached.
this page link just shows how many paths can leak. vast. and is not complete, as the TB has possible icing cracks that can leak. too.

assume all is bad, prove other wise.

sorry for long post, air leaks are complex, and can be, more than one, old cars love to do that. in spades

my page above html, is being published in Russian. soon, amazing,, huh>?
http://www.fixkick.com
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