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Ghetto fix for Idle Control Valve... Risky?

11K views 17 replies 9 participants last post by  benzbarz 
#1 · (Edited)
Trying to fix an intermittent idling issue (it would drop revs esp with load from a/c and lights), I read about a possible angle to check being the cleaning up of the idle control valve. So i removed the unit and cleaned up with brake fluid and replaced back, only to find I then had induced the dreaded high idle problem of 1500rpms. Maybe the internals of this valve were on its last legs and just gave up with the cleaning.

Exhausted all fixes including checking fuse to idle control, ICU itself, and removing and tinkering valve all last evening. This morning I thought that if my valve is just stuck in full open position, why not just seal the opening? Took racers tape (glorified duck tape) and covered 80% of the opening from intake manifold to valve. Started up the car to a nice 800rpm idle and 600-700rpm in D or N position. No more inconsistent idling too with a/c.

I can replace valve but cost seems high and honestly I'm pretty happy with the way it runs now. I am taking a risk here? Especially in cold weather when idling needs to be higher to warm engine (since i've effectively neutralized the variability of the valve).
 
#8 ·
Sounds like the valve was on its last legs anyway. Or stuck with carbon.
I've used all sorts to clean them and usually soak them for at least a week submerged. Brake fluid as opposed to cleaner was a tip from a mechanic recently that worked well.
They can have chunks of carbon in them that take ages to get out, I spent ages tapping one against the ground once, I did it for a bit each day and used a wooden skewer to move the slider about inside. So much crap came out of that thing and it worked well after.
 
#9 ·
Duh. That could be the problem then- I used brake cleaner though only a couple of spritzes and held downward so fluid doesn't get to coils. There is movement internally when I use 9v battery to test, but I think the flapper mechanism must be stuck or just broken. I will ask my indie next Monday to lend me idle valve to try. Personally don't want this "fix" but really can't help noticing that the car idles and runs so smoothly since I bought it a few months ago. Cold winter could bring issues. But honestly hope indie part works and if used he can give for less than $100 which will be worth the peace of mind. In my efforts last night to solve, I checked and tightened all vacuum connection points and now feel the engine runs better with economy needle pegged left even with some gas.
 
#10 ·
Flushed mine this week with starting fluid and brake cleaner until the return was pretty well clear, then connected it to the battery directly and heard a soft "thunk".

Bouncing the hot wire on and off the contact cycling a couple of times every second or so started the valve to clicking, and so I went back and flushed the valve with acetone.

Got back the nastiest stuff yet, alternated the battery cycles with an acetone cleanse (with dry and ventilated valve) to get yet more gunk, after three or four rounds of this the return was finally clear.

I was thinking of a dedicated hot wire to the valve then cabin and a variable resistor to the valve, and dial in your idle as needed.

Of course, getting it fixed right is better, but that does sound kind of neat.
 
#13 ·
Ghetto fix for Idle Control Valve



Actually that will not work to "dial in" your idle speed, because the valve is actuated by a solenoid (simple on/off functionality) and that is driven by the idle control module. The ICM regulates the valve by cycling voltage on and off in extremely high frequency (speed). This in turn results in an "average" valve position measured over a fixed period of time.

Your method would only apply increasing DC to the valve until sufficient was available to actuate the solenoid and it would simple "click in" resulting in a drop of engine idle speed to stall speed.

And, to add insult to injury, after several seconds the solenoid windings would burn out altogether, as it is not designed to handle constant current.

Cool idea though :p
-George-
 
#12 ·
That's the odd thing about the ghetto fix- the car drives really well ! Ran with a/c and lights this morning for 30 mins and everything was great! Including idle which no longer wandered around revs which happened after hitting 80c engine temp previously (symptom perhaps of idle valve pending failure).
The high idle situation really freaked me since 1500rpm in park made loud engine noise in public and more important caused reverse or drive engagement to jerk car which must not be good for transmission longevity.
 
#17 ·
Gotta come clean on this post. ghetto is ghetto.
My indie had no extra idle valve today so I'm off to cyberspace in search. Since my wife used the car all day today, despite my warning, I decided to peek into my "fix" -- found the racers tape to be softened from the heat while the adhesive started turning to goo (technical term). So I removed and replaced with a high temp adhesive free type of tape. Took 3 takes to fine tune idle back to 700, though now with lights and a/c the rpms drop to 500 on D with brakes applied. I've actually found posts where people claim their SL's work fine with the idle vlave completely removed. Somehow though, the car feels and sounds better with the unit plugged. Dont know why since it's almost rendered useless in my case. Wonder if the mechanism gets unstuck and so with my restricted air access will prevent the car from starting. In my playing around today, i learned that if my opening is too small (<10%) opening the car just wont start.
 
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