(05-15-2021, 03:12 AM)jwunsch Wrote: Update: IAC is leaking.

I did diagnose this bit differently. I did not want to use clay incase it would get inside my engine it turns real hard when it burns. And I wanted to avoid taking the TB out.

So here was my method. Create a batch "magic play dough" (recipe from near kindergarden).

1 dl = 0.422675284 US cups

1 dl of wheat flour
1/2 dl of salt
1/2 dl of cool or cold water
1 teaspoon of any food oil

Mix 5 minutes and its done. This amount would suffice for about 10-20 IAC ports, but its hard to make very small batch and its cheap.

If dough is too grainy, add water. If its too sticky add flour. If you cant get it not sticky like me add a few droplets more oil.


WARNING: This thing will eventually harden out and you need to hack it out of the port someway if you do not remove it until it dries completely. Tho it will take probably hellishly long to harden when its inside the IAC hole and inside almost tight plastic wrap.

(Original idea for the thingy is that kids can make pots and animals from it and then you can burn it hard in oven bit like you do with clay).


the best clay is not clay, it is called electrical mastic,, any electrician calls it monkey poop , spelled Monkey sh!t. it never gets hard and is super stiff and sticky, and will not suck in. done right. (a true art that , no?)



TRY1: Failure

Then I opened the IAC cover and put some magic dough into double layer plastic wrap and suffed the port, closed the cover and startup. 2 minutes ok and then rpm rose -> I shutdown engine. Plastic had failed due to vacuum and very small amount of the dough went to engine.

I removed dough. closed IAC cover in original setting and kept running eninge until white-gray smoke (and strange burning smell ended). IE.. dough burned trough engine. Let it run for quite a while after that to excrete any possible salt (if it had even had time to dry and crystalize as it dissolves in the dough).

Thanks for your words here, all,  and details, this is not easy to do this, takes great care to diagnose the guts of any TB.  (best is in a pan of hot water, on car super hard to do)
 

TRY2: Success.

1) open IAC cover
2) Line the huge vacuum port with extra strong aluminum tape. After that create 1-2 extra full rounds of alu tape lining. ( boy that is smart)
3) Insert double plastic wrapped dough into the IAC hole
4) close IAC cover with gasket.
5) Start.. idle rpm was 200-300 BINGO (by the gauge, which is unreliable at so low). Anyhow apply throttle to keep about 1000rpm until water heats and STAT opens.
but IAC is open cold , below 150F it is open the IAC and normal. what matters is hot.

And after that it kept running bit waving between 800-1000rpm  (my ISC is dead, diagnosed long ago, cant find replacement for the 89/90 thingy).
The ISC unplugged hot, the IAC closed like you did the engine can nor run at all.  ever, there is no air, but super tiny past the TV valve.
Keep in mind the ECU knows to wakes   up isc ISC as IAC goes closed.
Id you do the TV valve calibration,  set at the TV stop screw on 89/90 that is idle duty cycle settings for ISC , just screw it screw until the iSC wakes up and regulates at 800 rpm
then turn it in CW one more turn,

your ISC is bad or not calibrated,
make sure the gasket under ISC is not a wreck , has 2 holes not 2 cut to make one as some do when engine stalls cold.  
many folks cut the iSC gasket up to hide a dead IAc STOCK CLOSED FOREVER. (LIKE your previous owner may have had and done)
but your IAC works mostly.

id look at the ISC very  closely for DAmage of its gasket first. and see if coil is at 6ohms DCR  DC resistance, 2 times what 91+ reads. years.
the with no voltage to ISC see if it can close. as it must.
the ECU only opens it with modulated power. to it (PWM methods)


Anyhow.

What do you suggest for casting the hole shut? (I WOULD ONLY DO THIS (NO SPARE TB) In a way  that is regressive later (undo -able)
unscrew the TV stop screw CCW. see RPM fall. must, unless TV is 100% closed and that is not correct if closed on all 89/90s.



I was thinking I will apply aluminum tape again (to avoid any stuff going into engine) and then either use epoxy glue or chemical metal to block the IAC vacuum suction to TB and let it set for 48 hours or so.
try alum tape,  use high grade HVAC duct tape from 3M and then put plaster of Paris inside there,


Then I will apply a T-junction with rogue hose and moped's fuel valve into the cabin to have a bleed air valve for cold idle boost. (yes this can work and use any valve to calibrate it and one more to open and close for quick action cold. (or and home made orifice, calibrated in series for 1000 to 1500 rpm cold.
you will not be the first here.... others can not find the iSC sold or do not like the $250 price tags . then learn the ISC driver transistor in the ECU is blown.

(07-06-2021, 07:52 PM)jwunsch Wrote: Update: 1991 Vitara MT, 2 door, G16a, 4wd.

Very shortly after experimenting with golf tee I moved the hose on driver's side near driver's right knee and put a moped's fuel valve at the end of the hose to be able to tune the vacuum leak and have RPM control.

cold 200-2200 (fully closed - fully open)
hot  800-2500 (fully closed - fully open)

Note a needle valve would be a lot better for selecting RPM as its designed for gasses, this valve is for liquid so the whole tuning range is around 2-3 degrees of rotation. Bit hard to tune, but it does what is needed.

(07-06-2021, 09:02 PM)fixkick Wrote:

(07-06-2021, 07:52 PM)jwunsch Wrote: Update: 1991 Vitara MT, 2 door, G16a, 4wd.

Very shortly after experimenting with golf tee I moved the hose on driver's side near driver's right knee and put a moped's fuel valve at the end of the hose to be able to tune the vacuum leak and have RPM control.

cold 200-2200 (fully closed - fully open)
hot  800-2500 (fully closed - fully open)

Note a needle valve would be a lot better for selecting RPM as its designed for gasses, this valve is for liquid so the whole tuning range is around 2-3 degrees of rotation. Bit hard to tune, but it does what is needed.

wow, thanks for sharing all that data.  nobody has done this and posted the results. for building a fake,IAC valve, due to stock valve IAC stuck.(dead or weak)
that gas line valve is prefect. and easy to find too.

the dash gauge water temp uses its own 1 pin sensor and is not used for EFI , not used at all for the ECU for fuel mixing.

nice work and good luck for inspecting, get car hot, turn new valve for 800 rpm and bingo.
as you turn the valve , the ISC will kick in and do RPM controls HOT. to 800. (regulated ISC mode) hot.

i see yours did here. hot >>>> 800-2500 (fully closed - fully open)
 
the 2500 is because your  air leak is more than the ISC can control. 

try 1500 rpm cold see if when hot the ISC wakes up at 150F and goes to 800 like it should.


best wishes and cheers to you !


wow I missed your post before with super nice IAC packing job to take it off line..(leaking bad hot)  great photos those, and the method is perfect.
any method that can be Regressed easy  is best.  (blocking the base gasket also kills the air bleed in top of air horn, and is best to keep that working)

(07-06-2021, 09:22 PM)jwunsch Wrote:

(07-06-2021, 09:02 PM)fixkick Wrote:

(07-06-2021, 07:52 PM)jwunsch Wrote: Update: 1991 Vitara MT, 2 door, G16a, 4wd.

Very shortly after experimenting with golf tee I moved the hose on driver's side near driver's right knee and put a moped's fuel valve at the end of the hose to be able to tune the vacuum leak and have RPM control.

cold 200-2200 (fully closed - fully open)
hot  800-2500 (fully closed - fully open)

Note a needle valve would be a lot better for selecting RPM as its designed for gasses, this valve is for liquid so the whole tuning range is around 2-3 degrees of rotation. Bit hard to tune, but it does what is needed.

wow, thanks for sharing all that data.  nobody has done this and posted the results. for building a fake,IAC valve, due to stock valve IAC stuck.(dead or weak)
that gas line valve is prefect. and easy to find too.

the dash gauge water temp uses its own 1 pin sensor and is not used for EFI , not used at all for the ECU for fuel mixing.

nice work and good luck for inspecting, get car hot, turn new valve for 800 rpm and bingo.
as you turn the valve , the ISC will kick in and do RPM controls HOT. to 800. (regulated ISC mode) hot.

i see yours did here. hot >>>> 800-2500 (fully closed - fully open)
 
the 2500 is because your  air leak is more than the ISC can control. 

try 1500 rpm cold see if when hot the ISC wakes up at 150F and goes to 800 like it should.


best wishes and cheers to you !


wow I missed your post before with super nice IAC packing job to take it off line..(leaking bad hot)  great photos those, and the method is perfect.
any method that can be Regressed easy  is best.  (blocking the base gasket also kills the air bleed in top of air horn, and is best to keep that working)

Thanks hope that someone having same problems can use this thread to sort out IAC problems
. Also my goal here was to try to achieve debug and possible fix for the IAC without removing the TB from the car.
I had tested everything else except IAC and checked the TB gaskets.


I have previously diagnosed by ISC being dead too or then impaired by something (bad TV position?).

It does absolutely nothing when I turn on head lights  (only on 89/90 USA) or high beams. 80/90 only
Hot idle up pin reacts to defroster, but ISC does not. (heater blower, = defroster???) or rear glass of car resistor heater defroster?

91 does only dash blower in heater, idle up, and PS overload, (and rear glass heater only if fitted and does AC idle up if factor AC is present and working.
All iDLE ups are hot idle only, and  only work if hot engine, not cold.
idle ups are all ECU to ISC modulation methods called PWM.
IDLE UP MODES. FAIL
IF , NOT HOT ENGINE, 180F (common)
ISC clogged in side or coil inside open 
idle up pins into the ECU dead. (sensors for that wrong)
the TPS idle pin stuck at 5vdc ( means TPS is bad or just not calibrated using the factory TPS calibration that ends with TPS idle pin at 0v. (dask pot disabled)
Dash put stuck extended. hot idle. well this must be cured.
TV valve set wrong . stop screw. wrong on 80/90 but on 91+_ USA, it is set closed. and has bleed air screw in the front top TB air horn..
If at any time the hot idle is not normal 800rpm (+-50) that means the ISC is dead or just  off line. if off line idle up fails too, (a dual failure that0
ISC will fail if IAC is bad, if any device in the engine allows air to suck in illegally (IAC too) the ISC will fail, or even HUNT. (wild Rpm changes as ECU hunts the ISC like mad for 800)

this OP post is 91, not 89/90 and in USA those are totally different ECU and idle controls, for sure Idle up not the same.

My hot idle is around 650 with lights and blower. (hot or cold? engine) ISC only works HOT.
600 with lights + high beams + blower + seat warmer. 800 when all lights and blower off.
Feels like someone has tuned it to 800 on that setup.

Vehicle passed inspection 3 weeks ago. I just forgot to update the valve pic here and remembered it due to the "1989 screamer" thread.

I do not care the hot idle not being modulated as it does not affect my driving at all. Oil pressure is ok enough (light off), battery is charged even on such low RPM and engine never stalls even if I step on clutch and lift throttle suddenly during driving.

Ie the only pain it causes is that it does not keep 800 RPM. But here for pre 92 or 93 cars the emission spec is pretty easy. Certain emission levels & RPM <= 1000.

Newer cars will be tested idle and high RPM and for diesels box on neutral a engine acceleration from idle to max RPM on full throttle to see how much smog an particles they do.