No high idle

[ranger88den]

1995 Geo tracker, 1.6,16v, 4wd, auto trans.with new ignition parts, new EGR valve & system cleaned, new timing belt (engine timed to 5 degrees BTDC), valves adjusted, new radiator & thermostat, all fluids changed & trans filter, IAC cleaned, new Calmini header, new oxygen sensor & no ECM codes except 12. Here’s my problem, after starting the engine, there is no high idle, it goes right to 800 rpm and idles rough until warmed up. Any thoughts or suggestions? Thanks

[aquanaut20]

Check your IAC circuit

[ranger88den]

Originally Posted by aquanaut20

Check your IAC circuit

I checked the solenoid operation when it was off the engine for cleaning. I will check the supply voltage tonight. Thank you for the suggestion.

[jtgh]

there are 2 idle devices on this car.
1 for cold ( iac below T (water thermo controlled.)
and hot , idle control valve electric.

either can stick.

the electric one is dutycycle modulated at 200 hz. (ratio of high to low sets idle)
PWM type device. Puse width modulated device. it is.

but you can unplug it hot and rpm should change
then when hot , throw on heavy loads, a/c Head lights, defrost, radio, fan and the rpms should hold solid.
they can just be dirty.


my guess is thermo IAC is clogged with junk.

[ranger88den]

Due to my work schedule I won't be able to check the IAC until this weekend, but I will do the tests you advise, and post back. Thanks for the help.

[jtgh]

no problem we have people working problems for 30 days or more.
one person had 20 problems.

[ranger88den]

Well I pulled off the IAC, the coolant passage is clear, checked resistance (13.5 ohms) & and solenoid operation with power applied, tested okay and is clean. Have power and ground @ connector. Pulled connector off when engine to operating temp. and it puked out (tried this twice). With connector plugged in and load applied no change in idle accept when A/C operating then increase to 1000 rpm (200 increase). Still no high idle when engine cold (stays @ 800 rpm cold & hot). Any thoughts? Thanks

[ranger88den]

Little help?

[jtgh]

keep in mind: (TB = throttle body)

you see , on this engine , the ECU is dumb and cant tell rpm from Shinola. (lol)
it ONLY holds RPM what you set. HOT.
so set the idle bleed screw on the TB for HOT idle. ( it seems correct now)


idle is a tad complex.
this engine has 4 sources of air , all must be good at start.

1: throttle plate screw ( pray to gawd no one messed with this factory painted screw.
this sets the mininum factory air flow and must not be adjusted. ever)
there must not be sludge packed under said plate (EGR +PCV Gasses guarantee this to happen soon)

2: the below TB , IAC must be open cold and then close way down at 200F. (pan of cold then hot water test works)
subject to the same GUNK as mentioned above.
3: the ISC is the electric air device the ECU controls air at hot idle. (yours is good)
4: the Air bleed screws for setting hot idle.

conclusion.
id say. butteryfly plate is not passing proper air , for the 2 reason stated)
or the IAC below TB is bad or clogged up.




http://carfix.stufftoread.com/sensors/ECT-loc.JPG

http://carfix.stufftoread.com/sensors/93-mpi-smog1.JPG


my hidden fresh air page (buried)
fresh-air for start and idle

all is true cept Dash pot, ignore my DP coments on 16v's

the parts are the same , work the same but look different , they are not .
??A call for data:??
if some one has a 16v throttle body, can you measure the gap on the throttle body butterfly stop plate.
see opposite side of this photo and bell crank throttle.
it has a screw stop. measure gap with numbered drills shanks or calipers.
it is not in the FSM.
you find it , i post it on fresh air page.



no bids 5hrs.to go.
eBay Motors: LQQK! 1995-98 GEO TRACKER THROTTLE BODY/INTAKE MANIFOLD (item 200259357960 end time Oct-06-08 16:51:45 PDT)

[ranger88den]

jtgh,
I have checked the IAC twice and believe it to be good. I will remove, clean & adjust the throttle body as you advise. Thank you for the heads up on the auction, I won it and if the throttle body cleaning/adjust doesn't work, I will replace the IAC first, then the throttle body. As always, your help is appreciated and I will report back progress.