High idle, probably broken IAC, questions

[fixkick]

Thanks for confirming it.

I do suspect vacuum leak as the hot idle has been slowly creeping up. If I block radiator and let it heat so that IR heat-gun gives about 95C (203F) at stat housing I get idle bit below 1000rpm. Last year it achieved below 1000rpm at about 90C. So I will pull it apart and buy some gasket paper to make gaskets my self. At the same time clean everything from the TB etc.


Sadly now I have ISC and all gaskets for the newer TB and I already paid VAT and customs toll so wont bother returning it anymore. Probably not much market here for it, but cant help it. Oh well they weren't so expensive small loss compared to my stock market failings


I will probably depressurize the fuel line this weekend, have to see if I have enough time to pull the whole TB. Anyhow next weekend or something. I will take pictures and share them, maybe they help someone.


This particular vehicle is strange frankenstein piece of work. I have ordered with correct part numbers radiator (did not fit), brake booster (fit after hammering 1" dent to wheel well) etc. Luckily the parts dealer swapped the rad to another one and that did fit.

I am not sure if its because tag says its SWE car, but its has originally been sold by Suzuki dealer in Finland (neighboring country). Also could be that someone has scavenged parts from here and there and fixed it like this.

It has been owned by some safari company and they have made all kinds of self-made-patent-fixes all around the car.

And previous owner had made really shitty welding job and horrible electronics for additional front lights. I pulled all that crappy wire work away and did it properly this time. At least my wires are now water proof

any air leak (vac) will cause too high idle on the 8v (the map cause this, sensed vacuum change)
if all hoses do not leak and things on the end of them.
 and not the head to intake manifold leaking gasket
the it  must be  the TB,there is nothing left to leak. (assuming the above no leaks)
this TB has only 3 paths for idle air, 4  cause
ISC , IAC and TV.
1,2,3, one must be leaking. to solve this riddle, one only needs to do 2 things or 3.
1- unscrew the stop screw at TV so TV is 100% closed, (not normal this just  a test)
2: Dash pot retracted see that air gap at the DP end rod, that means it is not affecting idle. (as in pushing TV open)
3: then block the ISC gasket, just cardboard, from cereal box cut to fit and the  ISC is now 100% dead and no way to leak possible

that leaves IAC,  the tests for IAC are many some more hard.

pan of hot water test,. must closed 100% above 150f temp.
the look at the valve under plate 3 screws, make sure cone valve is 100% closed in hot pan of water
and last one can make fake or wrong TB base gasket even using a cereal box  cardboard, to block the IAC air hole in the bottom of TB , if this cures fast idle , BINGO
do know that when successful, the engine can not start up with zero air. no air no start; a big bingo that and can be cured  this moment with 5% foot throttle.

in all cases the ECU idle up pins must be false
our 89 has 1 pin for that. (and diode "OR" gate block to add on lots more idles  up, head lamps, blower, defrost rear glass. and PS overload and AC active. wow. )
newer ECU have 3 pins, or more.  all must be logically false,  or 1000 RPM is normal. but regulates, not wild.
if these pins are true (logic) ISC leaks air and causes that and is normal,  the ISC works on hot engine, and for 2 speed, normal and idle up mode.

I do hope you find the true cause,!!!

to find cause of this i block paths (sequentially additive) until found the leak.
this is not new, same year Toyota's all do this (work same way) same parts, in 90s'  

cheers to you sir ! and good day.