ISC solenoid repair?

[Nike]

Hello everyone on the forum. (My english is bad, I use google translate :/)

I recently bought a Sidekick 1989 years, EFI 8V. Of course, I immediately met with the problem of high idlle. (1200-1500RPM)
Since I'm an electrician by trade, and I will deal with reparation electronic assemblies European cars, I easily found the problem it caused high idlle - ICS solenoid. The problem arose in the gasket between the ISC solenoid and throttle body. Gasket is burned between the inlet and outlet sections. Considering that in my country almost impossible to find a new gasket, I handedly created a new one. After a visual inspection of the ISC solenoid I noticed that the solenoid valve (inside) do not seal it completely. (Does not close completely airflow inside) Also, in my country is almost impossible to find a new ISC solenoid so I am compelled to fix existing ones.
I am interested in the following:

- Does the ISC solenoid valve has to seal completely when no voltage, or a factory left a small gap for partial air flow when the valve is not active?

- Did someone tried to dismantle existing ones for reparations?

- Also, when the valve is in operation mode (the bright, cold starts, etc.) solenoid has a very strong sound work (strong klicking), while the expected increase in engine RPM does not happen, or happens very little. This now creates a reverse situation when the engine is cold, low RPM drop 300-400 RPM. When the engine warms up the normal RPM (800 RPM), but I have the impression that the ISC works no need to increase the RPM.

- Is it possible (by input wire) solenoid open for reparations? I noticed that for some trying, because underneath the rubber cover notices silicone sealant.

By the way, thanks to the author fixkick.com, because it helped me with a lot of useful information. I'm an electrician and I hope you'll help others on the forum in some situations.

Best regards from Bosnia and Herzegovina.
Nike

[fixkick]

Welcome ! NIKE.

Hello everyone on the forum. (My english is bad, I use google translate :/) OK

I recently bought a Sidekick 1989 years, EFI 8V. Of course, I immediately met with the problem of high idlle. (1200-1500RPM)
Since I'm an electrician by trade, and I will deal with reparation electronic assemblies European cars, I easily found the problem it caused high idlle - ICS solenoid. The problem arose in the gasket between the ISC solenoid and throttle body. Gasket is burned between the inlet and outlet sections. Considering that in my country almost impossible to find a new gasket, I handedly created a new one. After a visual inspection of the ISC solenoid I noticed that the solenoid valve (inside) do not seal it completely. (Does not close completely airflow inside) Also, in my country is almost impossible to find a new ISC solenoid so I am compelled to fix existing ones.
I am interested in the following:

- Does the ISC solenoid valve has to seal completely when no voltage, or a factory left a small gap for partial air flow when the valve is not active?
it is ok to leak a bit , most do.
the trick is to close the 89 rear throttle body idle stop screw so the ECU can gain back control of idle. (less air.)

- Did someone tried to dismantle existing ones for reparations?
just clean it and get it 99% closed. no power.
when it was newl, the idle would be like 500 rpm unpugged. so if it leaks to 600 rpm the ecu can still control idle. no problem.
what is bad is if you closed the ISC and the idle is 1500 hot, you have a huge air leak to the plenum (induction)

- Also, when the valve is in operation mode (the bright, cold starts, etc.) solenoid has a very strong sound work (strong klicking), while the expected increase in engine RPM does not happen, or happens very little. This now creates a reverse situation when the engine is cold, low RPM drop 300-400 RPM. When the engine warms up the normal RPM (800 RPM), but I have the impression that the ISC works no need to increase the RPM.

- Is it possible (by input wire) solenoid open for reparations? I noticed that for some trying, because underneath the rubber cover notices silicone sealant.

By the way, thanks to the author fixkick.com, because it helped me with a lot of useful information. I'm an electrician and I hope you'll help others on the forum in some situations.

Best regards from Bosnia and Herzegovina.
Nike

PS: watch out for the other center Throttle body gasket that cranks and sucks in, very bad.
PS2: yes, old ISC rattle badly. (it modulates at 200times a second)

91+ iSC has preload adjustments unlike the 89/90
http://www.fixkick.com/sensors/tests/IAC-exploded2w.jpg

89 idle controls
The vacuum dash pot device operates for 10 to 30 seconds at cold start. and retracts the rod 100%
then the IAC leaks air cold for fast idle until about 150F coolant temp point.
after that only 2 leaks of air, the ISC and the throttle plate.

i try blooking off the ISC holes, hot engine, to see what RPM I get. must be way below 800, id say 600 about.

if idle RPM is real high hot.
make sure throttle cables are slack never tight
unscrew stop screw for throttle , this lowers idle speed, so ISC can take over.
seen here,but is ok to adjust on 89/90 (ignore bleed ports here you dont have that)
http://www.fixkick.com/fresh-air/Slide_S...ge_11.html

if Dash pot device retracked.
IAC in base CLOSED.
http://www.fixkick.com/fresh-air/Slide_S...age_9.html
vacuum leaks. (anywhere cause this engine to race) and there are lots of leak points.

One more IAC test
http://www.fixkick.com/fresh-air/Slide_S...age_8.html


What i do is make sure i can stall the engine hot, buy blocking the ISC. if it races still, you do have leak.
if i can get the ISC to close and the ECU can use it ok, i then set the duty cycle of the iSC to 50%
using a scope or duty meter.
then 800 is no problem hot the ecu tries hard to hold 800 hot.

[Nike]

Thanks for the help.
Okay, today I again dismantled ISC solenoid. Logically, the solenoid could not produce sufficient airflow, because the holes that I previously drilled on the gasket was too small. Now I have expanded the hole to the correct size. Now the solenoid is functioning properly. Hot idlle, now holds approx. 800 RPM. Turned on the lights, fan, etc.. holds about 950RPM. I'm also closed with silicone mass back side of the solenoid. Inside there is a screw to adjust. I tried to move the screw-it did not work, screw lot pinched or cemented factory. Maybe it's better not to touch. Now ISC performs its function properly.
There is (perhaps) only one problem: In my country dayligtht is required by law, so my idlle still about 950 RPM always But not a big problem.

Attached a few pictures from work. Perhaps someone help ...

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[fixkick]

dang, the best photo set every on he 89 ISC>
super nice, can I steal them? do you have full size photos . nice high lighting work too, very pro.
that DRL deal, we can kill at the diode block,
the diode block sends the 950 request to the ECU on Idle up pin.
it can be defeated easy. that is if the rpm dont sag. , below 750. ive never understood why 89.98 needs this with same HP engine.

id not touch the preload screw if it dont leak bad. i think its set to very gentle preload. most gentle.

[Nike]

No problem, I'll send you the full picture quality on PM. You can freely set on your page. Photographed with a cell phone, so the quality is not expected, but can be used. My camera stayed home :/ I remember late

I know for a block diodes. I was thinking to break the information with the lights, but it can happen that the RPM drops drastically when the engine is cold. And I will do the test and see situation.

[fixkick]

they are very good. thanks.
I think the diode fast idle only works on a hot engine.
The IAC is wide open and is screaming..already when cold. up to 158F (150 on mine)
i think they might have been paranoid of alternator overload, causing ISC to lose control
say HL on + fan + defrost rear.?

idea:?
cut pin 3 to diode pack black-red, heck even the heater fan pink-black , id bet the 1.6L can hold 800rpm with alternator sucking 25amps easy.
be fun to try, for sure. the 91 can do it.
as you turn on the loads, the RPM sags a second and the ISC opens correcting the load drop..

im sure the alternator can handle most loads at 800RPM, the 55amp alt is same alt. same pn alt too. same pulley.
Maybe the old ISC cant suck at good.> (air)? or as fast? one mystery we never solved.
I do know it slower over all because the 91 can change spark timing to speed up engine fast and does. 89/90 cant do that trick.

[Nike]

I tried to unhook the wires ISC and turn the lights on when the engine is not fully warmed up. Indeed, she felt a drop RPM to about 400-500rpm and the engine is "troubling." Apparently, not well calculated transmission crankshaft pulley and alternator pulley. Loads on the crankshaft of the alternator is still too high when the engine is cold. But it was 1989 years

On newer engines that have been resolved in a different way. They realized that it is better to use the classic stepper motor which can be accurately leveled airflow compared to previous solutions with solenoid it works quite imprecise.

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Interestingly, the ECM does not attempt to correct RPM-based information about drop RPM, but it works on the basis of information included heavy consumers (light, fan, heater, etc.), or very low temperatures. In the case of low-temperature "role" will take over and termic "IAC".

I think there is a mistake made in the project. So, if the engine is very cold, the IAC opens part of the air. Also it works and ISC parallel together.
If the engine has warmed up, the ISC will be activated for a short time and it will be shut down until they include some of the consumers of electricity. (Information sent with diodes patch terminal, according to ECM)

This is where "holes". If the engine is only partially heated, it still lacks the necessary power to the alternator idlle turned effortlessly. In this case, the ECM does not attempt to correct RPM at this point based on the information obtained from the ignition coil. ECM is "expected" to IAC solenoid starts only if included large load current.

A little thinking ..... I hope you understand, since I use google translate

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Reading the service manual, you can reach many conclusions ... ISC always working on constantly PWM (Pulse Wide Modulation) at 20Hz. (Yes, 20Hz) So he has two states: Or is ruled out and can not work, or working on constant 20Hz.
Interestingly, regardless of the load, the ECM will not change the frequency of operation of the ISC. A little strange. : (

The information that the ECM receives from the ignition coil, used only to accurately timed fuel injection, but not for it to compensate for the RPM affecting the pulse width according to the ISC. I do not understand why he made ??this omission.

[Nike]

Looking at all the above, we can conclude: No classic push-pull relationship between RPM and ISC solenoid. ISC will be active only on the basis of external information and partially included short time after starting the engine. ISC will also be activated when the driver presses the accelerator pedal and the increasing speed, although I see no purpose ... Then the throttle already sufficiently open and open ISC plays no role.
Purpose of may be only a slight decrease in turnover release the gas pedal, wherein the air flow remains that the engine would not choked.

Maybe I'm wrong, but I think it works like this system.

[fixkick]

yes, and the ISC does more
it is used when you drive fast and cut the throttle to zero
this is the dashpot effect or anti neck snap effect , (isc is only air supply hot = tiny bleed) acceleration protections.

on some cars,. may be this one.
the ISC data for hot is stored, so at hot restarts, it is set to the last setting, for easier faster hot starts.

push pull, yes.
this happens for sure if the TPS idle switch is set wrong, set to open late.
this causes the ISC to fight you foot at tip in, its an ugly effect this.
that is why they use 3 feeler gauges. go, nogo and calibrate.

btw i have no knowledge of ISC actions with IAC wide open or at the magic 158F temp. gray area...