Just wondering what the correct method is..i know its on here somewhere i just cant seem to find it..
Cheers

as far as i know you unplug the ics and turn the screw to the point where the car can only just idle on its own then plug the ics back in, someone else can agree/disagree with me but thats what i read somewhere on the forums

Yeah thats what i thought it was....my idle is a bit erratic atm..it wants to stall sometimes when pulling into drive and idles a bit up and down at times...im wondering if it is the cam that was in the car when i got it...

tryed replacing or cleaning the ics? that usually helps, also clean the throttle body, could be the cam though,

Yeah tommorows list has grown lol..was just stezza install but is now clean idle control and throttle body

Oh well you will earn the right to a few beers down the willa pub in the arvo seems a popular place for the locals

Lol love the willa hotel!

I put this in OP's other thread too, but for benefit of others doing searches in future:

From the factory Workshop Manual for EF (ie. ford manual, not hanes or that other wierd one I've seen): With ISC disconnected, set idle screw to give 700rpm +/- 20 with 0.75mm feeler guage or shim in the adjustment gap. For checking idle purposes, 700rpm +/- 100 is acceptable - ie. the manual says to only adjust it if it's outside that range.

Do EF's have same ISC as EL/NL's?

My NL ISC with no power connected is open. This means that once throttle stop screw is set, my ISC can only reduce bypass air flow (by closing) so I reason that it can only drop engine revs from this point.

Adding a shim as described would seem to make this worse since once this shim is removed, there will be less air flow through throttle.

I have to say I've never used that workshop manual method - and I agree that I don't think it would work very well either - but again, I've never ACTUALLY tried it so can't comment intelligently about it. Part of my reason for posting it was to see how people fared with it but of course in general one can kiss feedback goodbye these days...

I always just set mine more or less by "feel" - ie. it's not too hard to explore the "capture range" the ISC seems to be able to cope with and put it somewhere in there - then if it tends to dip too much then bump it up a tad or if it tends to flare then knock it back a little bit.

The whole thing seems very imprecise to me to be honest - and I don't think that's down to the ECU or ISC being sick - a TI Performance module makes it all rock solid and idle isn't an issue any more - so I think it's crap programming by Ford.

Since I'm having trouble with mine, I decided to investigate further.
With no power, my ISC is open 3 mm or so.
Applying power does NOT close valve! This was a surprise to me. Applying power does NOT open valve either!

It seems that Applying power allows ISC valve to open more. This is not what I expected and it means that my initial post is probably wrong.

I have tried one experiment: I setup my ISC so I could see how it works. My ISC was modified by LPG fitter so it has an extra connection. This is used to provide vacuum for PCV.

Using this extra connection, I could block off my ISC port on throttle body and feed ISC flow into engine by another path.

Since I am having idle issues, what I found may only apply to me, but it may be helpful to others.

I found that once engine had warmed a little, by revving engine a little and letting throttle return to stop, my ISC valve would close. This seems to be caused by very high vacuum. My engine would drop and almost stall. At this point, vacuum would drop and ISC valve would open.

Since I can not see a direct link from ISC solenoid to opening or closing valve, I don't know why it is called and Idle Speed Control valve.

Last edited by philcolbourn on Sat Nov 17, 2012 12:02 am, edited 1 time in total.

Yes.

I seems these are made by Hitachi. One source http://www.justanswer.com/ford/2joeh-reading-posts-checking-codes-1993-bronco-5-8.html lists these functions:

The valve allows air to bypass the throttle plates and controls:
· Cold engine fast idle
· No touch start
· Dashpot
· Over temperature idle boost
· Engine idle load correction


I can see that some maintenance and testing is possible:

1. Replace filters on vent
2. Ensure tube in valve shaft is clear
3. Ensure end tube port is clean
4. Ensure valve seals when closed
5. Ensure valve shaft moves in and out.
6. Ensure about 10 ohms (use digital meter as there is a shunt diode)
7. Apply 10 to 14 V to terminals. Current should be over 1 A (I got 1.3 A using 14 V) in one direction. Due to diode, almost a short-circuit in other direction. WARNING: Use a current limited (2 A) power supply or you may destroy shunt diode.
Solenoid should obviously move, but you will not see any significant movement of valve. With 14 V applied, you should be able to manually move valve towards solenoid an extra few mm.

There is also a (rubber?) diaphragm that can not be seen nor cleaned. If this gets a tear or hole, it may significantly impact function. I suspect that differential air pressure on this diaphragm actually moves the valve and that its solenoid simple limits how much it can open.

That's all I know so far.

Ah! - being a servo type valve explains a lot!

I got my 'new' second-hand ISC/IAC/BYP yesterday and installed it today.

My idle seems to be fixed! I need to test it tomorrow when engine is cold.

It was very sooty/dirty so I 'cleaned' it with WD40. Later I did a proper job with isopropyl alcohol.

My thinking is that my ISC solenoid will be sealed for vacuum reasons and isopropyl alcohol should dissolve any excess oil and grime and evaporate quickly.

I sprayed into vent, both ports and into shaft vent (inside cylinder side port).

I shook it around a bit and dried it with compressed air. I also saturated vent filter and dried it too.

Now, what has gone wrong with my original one?

I have found related patents that describe how these generally work.

It is made by Hitachi, but this patent from BCD seems closest:

http://www.google.com/patents/US6382587?pg=PA2&dq=6382587&hl=en&sa=X&ei=nemmUJqKEYXwmAXxsoCYDA&ved=0CDQQ6AEwAA#v=onepage&q=6382587&f=false

These Hitachi patents are also similar:

[url]http://www.google.com/patents/US5188073?pg=PA4&dq=5188073&hl=en&sa=X&ei=5ummUK7lMKn0mAW09IDQCA&ved=0CDcQ6AEwAA#v=onepage&q=5188073&f=false
[/url]

http://www.google.com/patents/US6571766?pg=PA1&dq=6571766&hl=en&sa=X&ei=KuqmUJyPFYnmmAW-uoGICA&ved=0CDcQ6AEwAA#v=onepage&q=6571766&f=false

http://www.google.com/patents/US6065447?pg=PA2&dq=6065447&hl=en&sa=X&ei=m-qmUPeDDcihmQWpzIHwBg&ved=0CDQQ6AEwAA#v=onepage&q=6065447&f=false

You can see that there are numerous patents for variations on this theme and I did not find them all.

Some describe how certain features work, but it seems that my ISC is powered by vacuum and limited by its solenoid. It is very important to have these little shafts and vent holes clean. One patent discusses how it should keep working even if these holes get blocked - sort of limp-home-mode.