High idle, probably broken IAC, questions

[fixkick]

most of these OLD cars even 32 years old now.(89)
the IAC is bad, the  wax pellet inside goes bad and collapses and leaks air. ( the WHY)
just like the wax pellet  does in the thermostat in its housing coolant, at 10 years old. (for same aging reasons)
The IAC lasts way longer , 20 years or so....
there is no  easy cure, new TB are not sold now, only hacks possible.(or used dead TB from ebay even worse)
or the air hose trick per  poster. (simple for sure and effective) thanks for sharing, !

one could program and Arduino computer to modulate a new , generic IAC, but finding one is not easy , they are used in racing, but oops found one.

Idle Air Control Valve for BMW 325e

https://www.amazon.com/ROADFAR-Control-P...435&sr=8-3

the problem is what are the coils inside, is this a solenoid like Suzuki or  2 way motor with 3 pins,  I do not know. and must be known

there are 3 kinds of IAC (ISC in our case) in truth we only need 1 ISC not 2,(IAC+ISC) suzuki failed to do that and used 2.  (excuse is slow ECU then)
1: solenoid IAC (ISC) suzuki type now.
2: motor pairs as seen on EGR electric motor on 1996 J18 engines up.
3: stepper, as seen on my 88 jeep,4.0L
I know of only 3 kinds. but I think the below is #2 (100 % self contained, , no TB needed at all or wanted)

If I still had my 91' 8v and the IAC died, I'd be all over this, at midnight, oil time.

[jwunsch]

there are 3 kinds of IAC (ISC in our case) in truth we only need 1 ISC not 2,(IAC+ISC) suzuki failed to do that and used 2.  (excuse is slow ECU then)

Ok.. Nice to know reason or excuse for doing such a hack. I have not seen similar "hack" in any old car I have had.


I can confirm, no bleed screw found on mine. So I guess tuning the duty cycle would be quite annoying.


I will drive next week to our summer place so I will leave the ISC as is for now. Car works fine enough without it as I don't have AT creating extra drag trough torque converter so its very minor nuisance. 

With luck I might find analog voltmeter from there.. everybody has stored all kinds of shit from 1920's to nowadays so might even find one. If not I will try to figure out some meter when we return.


By the way, could one hack nowadays digital meters to measure average voltage from the control pulses if one puts rectifier + capacitor between the test terminal and power wire ?

[fixkick]

E17 market is Sweden ,sorry I forgot that. best is have signature in posts.
1991 Vitara MT, 2 door, G16a, 4wd. (market E17 Sweden, regardless of location this car is E17 no guessing)


there are 3 kinds of IAC (ISC in our case) in truth we only need 1 ISC not 2,(IAC+ISC) suzuki failed to do that and used 2.  (excuse is slow ECU then)

Ok.. Nice to know reason or excuse for doing such a hack. I have not seen similar "hack" in any old car I have had.
folks that race cars or go turbo or custom fuel injection do this all the time to all cars etc.  

I can confirm, no bleed screw found on mine. So for sure not USA CAR) So I guess tuning the duty cycle would be quite annoying.
yes no bleed = big pain. for sure. (jumping back and forth from TPS cal and dutycycle  i mad rush, then in USA 91, year all this pain ended. but not world wide.




I will drive next week to our summer place so I will leave the ISC as is for now.

Car works fine enough without it as I don't have AT creating extra drag trough torque converter so its very minor nuisance. what?
your  first post shows 1991 Vitara MT, 2 door, G16a, 4wd.

MT is not AT./ no mt has any kind of torque  converter,  I am so confused now.  and you are correct A/T box shifted Park to drive and NO ISC working will love to stall.


With luck I might find analog voltmeter from there.. everybody has stored all kinds of shit from 1920's to nowadays so might even find one.
the cheapest meter sold on earth is that, seen on all stores, even walmart here.  for $9 USD.



 If not I will try to figure out some meter when we return.


By the way, could one hack nowadays digital meters to measure average voltage from the control pulses if one puts rectifier + capacitor between the test terminal and power wire ?
that is  that stores peak voltage..


the problem with all digital meters is the maker does not tell what kind it really is.
so you know what sample and hold is?   it captures  the voltage on a cap in the meter the digitizes it. (using ACD)  and shows peak charge on the cap inside the meter.
others do ACD  direct and can read wrong, if it lands on a drop out. as a square wave will surly do.
there are single slow and dual slop ADC and DUAL do not lie ever. (it does 2 samples that must agree) and the removes noise from the signal. (we used to design them our our company)

other meters most costly have   a duty cycle mode, that works.

then AC mode a meter with RMS mode will read RMS of the square wave and that is wrong, so will any meter this is non RMS (cheap meters) that too is wrong

the problem is: It is not DC, nor is it a sign wave but is  square wave,.

VOM= in Volts DC only mode.
a needle meters has zero electronics inside, (DC) just resistor voltage dividers.   and the meter is just a coil (a 1/2 rotation DC motor is in the meter) pure copper and 1 magnet bar.
VOM im volts mode, are cave man simple and are very useful still,  for sure doing averages.


this allows it  to average, (true)
analog in this case means NO ADC, no digitizer.
and has just needle.


https://www.walmart.com/ip/Leviton-Range.../302081068

UK?


https://www.ebay.co.uk/sch/i.html?_from=...0&LH_BIN=1



all stores here, auto and walmart and hardware stores (home depot,etc) sell cheap $10 needle meter, VOM  imported from china.

nothing works better unless , scope or duty meter feature DMM.

sorry that I could not see your whole , TB< if had, I'd know it was outside USA. ( my bad I did not look up your firewall tag and see COUNTRY code there)
I  can the see all parts on any car any country up to 2004.  (data base here)



here is my duty meter,  and does work tried it.


https://fixkick.com/IDLE-AIR/dutycycle/9....html#2800


WAY #2 (not in any book)  i CALL the CAVE MAN WAY, THE LESS TOOLS THE BETTER? (no hammers or clubs, sure)


works only if IAC is good or blocked, and AUX air is used (your hack) and you are not the first to do that  here.
turn the TV, stop screw and get 800 RPM (must be normal hot engine)
then set the TPS (calibrate screws loose) so the idle switch is (has) just  closed. monitoring the TPS idle pin, 0v is closed, 5vdc means idle is DISABLED. 0v is good , just  barely into, 0v.

end.

the goal is the the ISC to wake up on a hot engine, and work and regulator RPM at 800. (cold rpm is your hack valve, by hand set)
good luck to you.....

the problem is if set wrong and the idle switch is late to open(0 to 5v transition) the ECu will fight your right foot, and bog/hesitate )

what I do is set the TPS switch using the feeler gauge first
https://fixkick.com/All-Pdfs/M89/TPS/89-...ation.html

what you can try is to set the TV to TV bore air gap like ours 91, to 0.001 or 0.0005" not fully closed but so closed it can NOT JAM (see that reason?) (your hack is the new air bleed, see? )
then set the idle switch to using 2.2mm feeler gauge.find the zero OHM to infinity transition point using the 2 loose TPS screws and C/D pins on TPS. (low ohms scale or 2k ohm scale seems best)
this will set the TPS correctly. for idle switch actions. ( the key factor is when your right foot moves down even a bit the ISC goes OFF LINE fast. (or it will fight you)
then ready to drive.
then to start the car add air using your hack cold start needs air so add it with HV hack valve.

and when hot engine or near, then you start to close your hack valve until 800 RPM is hit and drive.
on A/T car that is more tricky. for sure if wrong ECU in the car. (MT ecu in AT car?) but your car is MT well was when new.

cheers !

[fixkick]

E17 market is Sweden ,sorry I forgot that. best is have signature in posts.
1991 Vitara MT, 2 door, G16a, 4wd. (market E17 Sweden, regardless of location this car is E17 no guessing)

with the wrong meter, digital
and diode and a cap. say 1UF 20Vdc.

the diode converts AC to DC called rectification.
the cap charges to peak. input voltage.
unless it is huge uF and has a resistor added.(IDK), and then the voltage is less. to do laws called RTC time constants. T=RxC. (R = 0 = wire)
so there is no answer. lacking cap value. but...
a small cap used will charge to 14vc fast (alternator voltage) charging voltage. 13.3. volts is battery float voltage, not charging nor discharging (lead acid car battery)

this is all useless, as we want to know actual duty, 50% high then 50% low on the square wave that is 2.5mS high , 2.5mS low. Period is 5mS. 0.005 seconds.
it is so hard to do that suzuki sold there own meter to do that just for this car, the FSM factory manual even names it.

the ISC has a 2amp driver , (6ohm coil ISC) this is very powerful signal
and in to any meter , the meter is not going to load down that 2 pin wire set
adding a diode to that pin is not any kind of resistance (T = RxC) R = 0.
that means the cap (added to end of diode) adds no resistance and charges to peak.
the DIODE then reverse bias (off) and the cap can not discharge to the low state driver or to the coil ISC, so sits at 14vdc all day long.


do your really have Automatic trans-missing?????? or the MT 5 speed.

the ECU for A/T box is unique.
that A/T ECU actually sees you shift out of park and (park pin goes to false logic) the ECU changes to a very aggressive new idle controls to heat up (joking 1/2) the torque converter clutch.
The magic ISC then holds 800rpm hot doing that,using totaly more aggressive ISC tables of modulation.
if the iSC is dead the engine stalls or on very good engines runs a 200 rpm and does not.
when you move the throttle with the right foot 1mm the ISC goes off line, dead ISC by design or the driver will crash (ask Toyota how billion $$$ law suit is to lose on that)

My 91 has the ISC hunt error, a true man killer , in A/T (teens etc not wise) it hunts like mad if he DP fails. and no lawsuits yet.
in drive it is a man killer (no me) for sure, in DRIVE, as car lurches madly ahead
so do you have A/T tranny??????

[fixkick]

LAK625K17
let me decode that.
L =metal top
AK = 4 seats metal top
62 = 1.6L MT trans 5 speed.
5-= JLX grade.
K= Type 1 engine 8valves.
17= for sweden export. market codes
there was no automatic transmission in this car day one new.

[fixkick]

IAC is in TB there were 2 TB , used, 2nd below after vin serial 000111445

13400-61a00
13400-61a60

never used in USA ever. but the IAC is deep inside, as you know.

[jwunsch]

Car works fine enough without it as I don't have AT creating extra drag trough torque converter so its very minor nuisance. what?
your  first post shows 1991 Vitara MT, 2 door, G16a, 4wd.

MT is not AT./ no mt has any kind of torque  converter,  I am so confused now.  and you are correct A/T box shifted Park to drive and NO ISC working will love to stall.


With luck I might find analog voltmeter from there.. everybody has stored all kinds of shit from 1920's to nowadays so might even find one.
the cheapest meter sold on earth is that, seen on all stores, even walmart here.  for $9 USD.


My 91 has the ISC hunt error, a true man killer , in A/T (teens etc not wise) it hunts like mad if he DP fails.

Thanks again for that info package. I think I now understand how to correct the ISC issue.

Mine did hunt before when semi warm until I hacked the IAC. It did not affect driving much. So yeah that confirms with A/T the hunting is really bad, probably due to the very aggressive ISC profile. And I dont pull from full stop with MT without pressing throttle pedal, so that also eliminates the ISC.


Sorry for being bit confusing there. I mean to say that ISC not working is very minor minor problem as I have manual box. Also meant to tell that I know it would be huge problem with A/T as the engine would stall when switching to Drive.


My country has only 5.5M population and spread across quite a lot of land. So we have limited selection of tools and stuff on shops. For example I have not seen analog voltmeter in 20+ years. Have to look up internet, someone on EU area must be selling those.


I took a pick of my TB, sorry could not get to better angle with my camera. I marked one spot with red arrow that looks like it could have a screw, but there is only short cavity without screw.


   


I know sports car tuners and race car guys have all kinds of exotic systems. I was helping my friend as a bolt/wrench boy role when he built his Mk4 Supra.

From stock 330hp twin turbo to 1000+ hp single turbo ethanol monster... new ecu, new injectors, whole engine rebuild with stronger parts, 3 plate clutch, hardening gearbox, brakes, springs, shocks... so basically chassis and seats stayed as they were.. Self made ecu map and the works. Can just say that wow it was expensive and wow you really need the seat's backrest with that one. And maybe some driving skills.

[fixkick]

Car works fine enough without it as I don't have AT creating extra drag trough torque converter so its very minor nuisance. what?
your  first post shows 1991 Vitara MT, 2 door, G16a, 4wd.

MT is not AT./ no mt has any kind of torque  converter,  I am so confused now.  and you are correct A/T box shifted Park to drive and NO ISC working will love to stall.


With luck I might find analog voltmeter from there.. everybody has stored all kinds of shit from 1920's to nowadays so might even find one.
the cheapest meter sold on earth is that, seen on all stores, even walmart here.  for $9 USD.


My 91 has the ISC hunt error, a true man killer , in A/T (teens etc not wise) it hunts like mad if he DP fails.

Thanks again for that info package. I think I now understand how to correct the ISC issue.

Mine did hunt before when semi warm until I hacked the IAC. It did not affect driving much. So yeah that confirms with A/T the hunting is really bad, probably due to the very aggressive ISC profile. And I dont pull from full stop with MT without pressing throttle pedal, so that also eliminates the ISC.


Sorry for being bit confusing there. I mean to say that ISC not working is very minor minor problem as I have manual box. Also meant to tell that I know it would be huge problem with A/T as the engine would stall when switching to Drive.


My country has only 5.5M population and spread across quite a lot of land. So we have limited selection of tools and stuff on shops. For example I have not seen analog voltmeter in 20+ years. Have to look up internet, someone on EU area must be selling those.


I took a pick of my TB, sorry could not get to better angle with my camera. I marked one spot with red arrow that looks like it could have a screw, but there is only short cavity without screw.





I know sports car tuners and race car guys have all kinds of exotic systems. I was helping my friend as a bolt/wrench boy role when he built his Mk4 Supra.

From stock 330hp twin turbo to 1000+ hp single turbo ethanol monster... new ecu, new injectors, whole engine rebuild with stronger parts, 3 plate clutch, hardening gearbox, brakes, springs, shocks... so basically chassis and seats stayed as they were.. Self made ecu map and the works. Can just say that wow it was expensive and wow you really need the seat's backrest with that one. And maybe some driving skills.

just be sure the TPS idle switch is closed at hot idle and driving will be so  much better. (ok, still M/T) great.


one other way (food for though)
using and old VSV valve,  vacuum solenoid valve, like what is used for the dash pot?

use these with 12v( ign, on) power wire to and added   VSV (vac, solenoid valve) and a toggle switch.
then with the VSV  and a tuned 1 orifice  ,  . you have binary controlled bleed valve.  for cold operation.
or 3 way VSV for hot/cold and 2 orifices..
then tune the orifices one for hot and one for cold.  

set (tuned  before) one way for cold and 1500 rpm
as engine warms the 1500 goes way to high(too much air) "screams RPM at bout 150f water temp"
then throw the toggle switch and 800  ISC regulated RPM happens.

then latter you could add  thermal switch  device to water hose (a sensor) that closes (using a relay) to the above. toggle switch now removed.
using sensor you choose as best,  150F or what ever you want ovoid the screaming RPM that you wish to avoid.

note how this way is progressive from very simple to more complex but still easy to over time. (improvements)

3way  (output to way 1 and way2 path)
https://www.summitracing.com/parts/rnb-911-404


2way (open/ closed) (fo cold engine only)

https://www.summitracing.com/parts/rnb-911-601



cheers had happy summer !