1989/90 , new free(?) ISC gasket. printed

[fixkick]

I have never scoped any 89,  they are very rare.  those years. for sure ones that actually run,   Just saw my 1st Sidekick running here in the south, in the last full year.
2door 95. red. and ratty shape,
but one of the best 4wd offroad and show cars made, IMO.  light + best. and low CG.  
see this: http://www.fixkick.com/videos/AVI/kickin.mp4

i forgot to say
to makes sure actual hubs (lockers) are not bad must remove them, and drive, this exposed the bearings to road dirt but do so on pavement say around the block safe.
it simply unbolts, (outer inboard bolts)

So as the complete cycle on the 89 is 60ms based on my scope pic it seems it is around 16hz at 50% duty. As the freq doesn't change but the duty yes , I suppose there is a resonance for some frequencyes or a broken spring inside but as it is regulating nicely I don't wanto to open it and risck to loose the regulation. Before this was thinking to double the frequency or change the regulating valve with a newer applying a flange port. We'll see. By now the rattle in some condition is exactly as in this video https://www.youtube.com/watch?v=6tWS7DGXtNA

that noise is just wear,  they all do that, this old but keeps working, so is only noise issues.
F= 1 /T    1 / .060  = 16.7 HZ.     (3 times slower than any  91 up , THANKS FOR that DATA! ) maybe this old ISC is  just 3 times slower to react (mass ) 91 is totally newer design.

one can buy a stepper motor, ISC,  even get them off vast cars sold.  (Jeeps have it, a rotating, ISC valve. stepper motor it is)
make small ARM cpu or Arduino CPU,  program it to do PWM from CPU out ISC port , to stepper, drive.
They make stepper motor drive chips cheap, and makes doing this super, easy. software wise.
even a look up table to do PWM to stepper, works.
There are sold ISC stepper valves in a box new, sold, at say , summit racing. (valve stepper motor and valve body all in one) and 2 air pipes to it.

nice video of a worn out ISC<  classic,   16 times a second STROKED, say , 2hrs a day to work and back. is what.?
1billion cycles in 30 years very light usage.   really amazing to me it didnt catch fire. (or just seize)

EOL is EOL.  once again.  find one on ebay  used and pray for only 1/2 that usage.?

or to like others do,  block it 100% and set idle just like a  Carb, HOT( the TV stop screw does that) but when cold and IAC is wide open the engine RPM may be untenable.


that is about all ways to do it , i think. (if you double the PWM frequency I bet it just acts dumb,  due to huge mass of the valve inside)