how high? RPM ? not 800 and steady hot and holds there
with headlights and heater fan on high?
which engine? US had
2.0 L 3S-FE I4
2.0 L 3S-GE I4
the first thing that must happen, is water temp,. coolant at 180F or more. holding sold, hot. if not , it will never run right.
if the coolant is ok.
there are vast ways to fail idle.
(not just the stuck (clean it) ISC/IAC electric air valve.
idle is the last thing to work right on all EFI systems.
if the engine misfires to bad, the ISC can not adjust for this.
if the engine floods and misfires, same,
if the AFR goes real lean, same.
iF in the USA, (are you) we have OBD2 in 1996
so scan it, got DTC errors, BINGO ,huh, easy, all scan tools work here, and are borrowed for free, (the zone) or bought for $9 (ask)
too high and too low are trouble shot different,
so too high
this can be stuck ISC or blockage under the throttle plate.
Throttle valve, butterfly plate. this common as the EGR cloud
hits the PCV cloud and muck (gunk) happens
what i do is see if the EFI is running in closed loop status
at idle, if not i fix that first, then worry ilde speeds last.
idle is ECU controlled at all times. so... let it.
if not in closed loop hot that means the AFR mix is wrong
and the 02 sensors is stuck.
find out why.
where is LTFT? long term fuel trim? -40% (bad) +10 or -10 ok
-5% is perfect.
if it is inclosed loop , i do ISC test now.
i check to see it opens and closes, with tests.
or clean it and see if it does work right.
here is the iSC test
the coil is 17ohms.. is it?
in some cars there is a thermal only iAC,
it must close 100% on a hot engine
or its bad or the 2 small water hoses to it are blocked.
some cars have 2 air valves , others 1, depends on year, and engine
country and EFI, type, lots there are on 3S engines.
is see no IAC thermal online at alldata.com
but i do see a vacuum servo (dash pot there)
make sure it does not messup idle. by , pushing the throttle open
too thight throttle cables, anything at all stopping the Fly plate
from closing 100%?
i looked on line and see no MAF sensor , so its a MAP,
and all MAP sensor EFI systems race idle (full power)
with any air leaks
(vacuum leaks anywhere below the FLY plate.
Fly as in butterfly Throttle valve (vacuum hose cracks)
all, cars do that , if it has MAP speed density systems.
also the ECU has an idle up pin, if its active , it will idle up
the FSM cover s why? up to 5 reasons.
lots of way to have idle mess up
here are more.
The TPS not signaling IDLE.
DTC P0120 or 121 , bingo, TPS issues.
id scan it, id drive and scan it. and log it.
post scans and can point to problem.