basics IAC testing.

[jtgh]

normal ,
idle is set hot. (with bleed) and DP is retracted. ( as yours is .good)
Issues?. someone moved the butterfly stop screw, then set it to .25" factory setting.
see my blow up photo.
then make sure the bottom IAC-therm is closing at 140F (fsm spec)
warning that gasket always breaks under 3 screw cover (inspection port)
I glad you did a vac leak spray or gas test !


it is a tricky blance.

I take it you pinched all the hoses to find out who contributes to air ?
brake booster hose. PVC hose (visually only) , evap not leaking (hose or connections)
egr hose not leaking manifold to vsv valves.

Bells ringing?
you told me IAC-E , hose input , that if you plugged it , then the idle was still too fast.
if THAT is true, hot, then the you have an excess leaker. some where.!

Dash pot:
it is calibrated hot (last) after a perfect 800 idle is achieved.
(pull a vac on it , hot and set it to 2200 rpm hot.
after this cold starts will be 1200 cold. (set hot , to get cold rpm) funny huh?

your dash pot is working.
it retracts ( lets troubleshoot hot starts and idle)


you can NOT get 800 right.? HOT ?


I will be doing mine tomorrow am, so will feed back to you my success or fails.


An on car IAC-E calibration?. , hot engine (for stability) , pull iac -e conn plug.
then plug up its Air nipple with finger, most air should be blocked.
and idle shouldnt change.
if this nipple can drop idle greatly ,then try adjusting that IAC-e end screw.
try to get 800 rpm.
better ,i think, is to try to lower idle until you can lower it any more. then stop.
going to far , limits the range the IAC has.

i will try tomorrow.AM.

cheers.

[LongRod]

"Bells ringing?
you told me IAC-E , hose input , that if you plugged it , then the idle was still too fast.
if THAT is true, hot, then the you have an excess leaker. some where.!"

No not true. If I block the air hose going to the IAC, my idle drops to a perfect 800 rpm. My goal is two fold. I'd like the IAC to automaticially drop the idle to 800 rpms or lower after the engine is fully warm and I'd like the car to start as quickly when it's hot as it now does when completely cold. Thank you Jerry for the GREAT advice so far. I would have never known to clean out the IAC without you. I'm anxiously awaiting your results.

[jtgh]

Originally Posted by LongRod

"Bells ringing?
you told me IAC-E , hose input , that if you plugged it , then the idle was still too fast.
if THAT is true, hot, then the you have an excess leaker. some where.!"

No not true. ah but close !
If I block the air hose going to the IAC, my idle drops to a perfect 800 rpm.

but that is not good, the IAC must be able to go below 800 and above equally. that is its job 1. (lol)


My goal is two fold. I'd like the IAC to automaticially drop the idle to 800 rpms or lower after the engine is fully warm and I'd like the car to start as quickly when it's hot as it now does when completely cold.
both goals are perfect. me too.

Thank you Jerry for the GREAT advice so far. I would have never known to clean out the IAC without you.

I'm anxiously awaiting your results.

all good data.
you do have a leak , and it is not the iAC. your finger proved that.

the odd thing.
hot start is bad,
I wonder if yours has too much air hot staring ,and is too lean.
maybe, and if true, that would explain high hot idle?

if sure no leakers, Ill hoses gaskets not leaking and the IAC thermal leaks
a tad, then use the buttery fly stop to drop idle to 700 , then use air bleed to bring it up to 800 with DLC freeze Duty jumper set.

this latter part im playing with now.


I put my spare , iac thermal in the oven and at 150F the main valve is/was
closed fully. that is a valid test and is says in book 158F is spec for closed
some mine 2 spares , close at that point.
if you need a working bottom iAC-T , i have one for free.

if yours is off , calibration.

this old car is rube goldberg style ( 5paths ) newer cars,
ECU just pounds the IAC main for any rpm it wants and is hard coded the
800rpm . no tach ever needed.
but it is challenging to figure a way to work the balance.

i think it is possible.



cheers.

[jtgh]

the only pain so far, is my Duty cycle out port , on the DLC , is dead.
(scope, Duty meter and , analog dc meter , all 3 flat line during the duty jumper mode)
may be ECU knows IAC is dead.

I will retest all that.
on the 8v , i discovered that one needs a jumper form the DLC duty out , to the
12vdc battery via a 330 resistor , and you wil get a 6vdc square wave.
i traced the circuit out.

If i can get the pin to wiggle I can actual show how to recreat the original Suzuki
duty meter ( it is really a current meter , !) that is there secret.
FSM says connect TECH1, ouch. if no real duty meter.

on the 16v they used a voltage out driver.
but that is getting ahead of my self as , first i gots to fix it.

cheers.

[LongRod]

Actually when I put my thumb over the IAC air intake, the idle probably does drop to under 800 rpm. I don't know how to measure this as my car has no tachometer and I have no idea how to hook up my 1960's vintage dwell/tachometer but I would guess that I drop to between 600 and 700 rpm when the IAC air is blocked.
When I remove the "IAC-thermo" end plate (held with 3 small screws) is there anything inside that I can clean, measure or adjust without removing the whole unit from the car?
Since the car will only restart HOT if I hold the gas pedal to the floor (secret unflood mode) I merely assumed I was getting too much gas. I have noticed since I cleaned my IAC, the exhaust has gotten smoky (blue smoke) even when hot. When the IAC was clogged and frozen, the exhaust was clear. Very strange!
The throttle stop screw (butterfly stop) has never been adjusted or changed from the original factory setting. The butterfly valve and and inside housing is squeaky clean with no varnish, gum carbon, dirt or other deposits.

[jtgh]

mine 10 mins ago.

new IAC (rebuilt my spare)
start it and warm it up.
close bleed because my idle is way to high.
it goes to stops at 1000 (IR gun tacho)
hummm
pull iac-e elect. and idle drops to 700
put back.
i check for vac,leaks , none.
so I close down iAC-e screw until i hit 800.

but when i test the iac by putting loads on my engine (HL and fan) rpm drops
so my ecu is not controlling iac-E CORRECTLY. SCOPE SHOWS good pulses.

i must have ECU issue or some other input to it is wrong. will sort later.



your IAC should not cause smoke after start, the MAP takes over for AFR . after start.

you have another problem too.

hows that addages go about bad things, in threes? ( lol)

[LongRod]

I guess it's time for a new tool purchase. Does Harbor Freight sell a reasonably priced (i.e. dirt cheap) tachometer? What type of tachometer do I need for automotive testing and where is the best place to get it?

[Rhinoman]

Originally Posted by jtgh

on the 8v , i discovered that one needs a jumper form the DLC duty out , to the
12vdc battery via a 330 resistor , and you wil get a 6vdc square wave.
i traced the circuit out.

The 330R resistor is bypassing the ISC, you will get 6V even if the ISC is burnt out or disconnected. You should see 10.5-11.5V if everything is good. Have you checked that you do have a 12V feed to the ISC? Also have you tried interrogating your ALDL interface to see if the duty cycle matches?
Cheers
James

[jtgh]

i got a cheap Laser gun Tacho, called a DT2234a on flee bay.

thanks James:
my description was bad:
on my kicker the 8v has a DLC port called Dutycheck output. pin a9
I jump B to C to DCL , "diag. switch term" to ground for IDLE Duty check.

on this car of mine and many others here nothing happens on a9 as book shows
duty meter connects.
i traced the circuit and found this. via r238 330 ohms. to open collector transistor.



this pin can not source current,
http://carfix.stufftoread.com/ECU/Da...2-pin-outs.jpg

the 8v manual says a special suz .dutycycle meter is needed.
my newer 92-95 says 8v same meter, or scan tool.
same book shows analog meter ok in 16v. or scan tool tech1
and on 96 , it says any digital voltmeter will work on 16v.

i then put a series 330 ohm resistor from A9 to +12v ,
Evoking the DLC BtoC jump, A9 (pinA) it goes to 12v. ( off full time ,with scope)

i can not get q105 to wiggle, no matter what i do.


My perceive idea of why all this method, and not just connect to IAC direct is that is hard to do backprobing and all. ( my signals to IAC. real are ok)

so they created a duty-cycle mimic port, but it dont work.

i even followed the key off , place jumper and count to five as the book says.

i traced the pin 8 pin of Q105 and it is clamped to12v via a diode. ( and is good)
pin 4 of q105 is grounded.

i will try more ecu's, i have.

i was hoping to get a 6vdc square wave, with my crude current to voltage setup.
on pin a9. DLC pin A.

Thanks for helping.
jerry

[Rhinoman]

I have missed that off my schematic, I have it sketched out somewhere but I'll recheck it anyway. I haven't had a chance to check it on the vehicle yet, I don't have a garage so I can only work on at at weekends when the weather is OK. On the 6-pin connector the duty output terminal will output ISC or injector duty cycle. You should be able to get duty cycle by connecting the meter +ve to 12V and -ve to the connector. I wonder if the 'proper' duty cycle meter is seperately connected to the battery supply.