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Discussion Starter #1
Hi All

I have a high idle issue with my 1989 900 EMS.
I replaced the NTC yesterday and when the engine warmed up the idle droped to normal (hooray) for 30 seconds then went up to and stayed at 1500rpm (boo).

On squeezing the hoses that go into and out of the AIC, the revs drop.
Before I splash out on a new AIC, is there any way of actually testing the unit (such as applying a variable DC voltage (0-12v) to see if it is actually working?

thanks
Neil
 

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It would be difficult........

The ECU drives the AIC by supplying a "pulse width modulated" d.c. voltage, a high frequency square wave signal. A flat d.c. voltage will most likely drive the AIC valve either wide open or closed as only one coil of the stator is energised. A basic resistive check is as much as one can do with the AIC in the hand. The coil resistances should be equal or very close to equal.
 

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Discussion Starter #3

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Neil_G said:
Hi All

I found this while searching:

http://www.thesaabsite.com/Saab%20900%20&%209000%20AIC%20Testing.htm

If this shows that the AIC does not work, then I suppose I will have to stump up the AUD$150 for a new one (on a car that cost me AUD$200!!)

Oh well - such is life

regards
Neil
Is that the silver one that was for sale in East Freo, Neil? My wife wouldn't let me buy it -- no room, she said, or some poor excuse like that.
 

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Discussion Starter #5
East Freo Car

Hi Special Tool

Yes it was that car.

I used my usual excuse that it is worth buying at that price for the manual gearbox alone!!

I had to replace the HG and have some welding done on the head, but except for that (and this damn high idling issue) overall it is a good car - even the AC is cold!!

regards
Neil
 

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Glad it went to a good home, Neil. Unfortunately for me I was in the middle of another head gasket/hoses/general TLC job that was stretching out due to illness and time constraints, so my wife wasn't keen on taking on another car that needed work. Those sort of bargains don't come along too often over here though.
 

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Discussion Starter #7
AIC update

Hi All

After resigning myself to having to replace the AIC, I thought that I would have some fun with the old one and see if I could get the non serviceable unit apart - well that was the plan.

Firstly I tested the resitance of the unit and it was in spec (8.2 ohms v 7 +-5) - good. I then started to drill out the small circular fills on the side of the unit. However after doing two, I noticed some black flakes of gunk fall from the unit.

Until now, the valve was stuck and would not move. Looking at the unit with the electrical connection to the top, the valve was open about 4mm on the left. I assume that the vibration of the drill had dislodged some gunk and now the valve could be moved the 4mm to the left to close fully.

I then ran a whole pile of kero through the unit again followed by WD40. I started to be able to get the valve to move the 4mm on its own and return via spring pressure.

I put it back on the car but as the valve was fully closed the car would not idle - but the idle was low and not high - progress!!

I then did the whole cleaning process again and I was actually able to move the valve fully across to the left - and not to the right as previously thought. After filing off a slight lip on the valve that was causing it to partially stick, the valve now freely moved from the right giving a 4mm opening on the left of the valve across to the left to be fully open on the right (if that makes sense).

The AIC valve was put back on the car and it idled normally - hooray. So $150- saved for the time being.

So the reason for my story is that I was actually trying to force the valve to open fully the wrong way - it opens on the right, not on the left where I had the 4mm gap.

enjoy
Neil
 

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Neil_G said:
However after doing two, I noticed some black flakes of gunk fall from the unit.

Until now, the valve was stuck and would not move. Looking at the unit with the electrical connection to the top, the valve was open about 4mm on the left. I assume that the vibration of the drill had dislodged some gunk and now the valve could be moved the 4mm to the left to close fully.

I then ran a whole pile of kero through the unit again followed by WD40. I started to be able to get the valve to move the 4mm on its own and return via spring pressure.

<snip>

The AIC valve was put back on the car and it idled normally - hooray. So $150- saved for the time being.
Saves me having to post an "Is it all gummed up? Would it benefit from a damn good clean?" reply... <grin>

The one on my Lucas car was giving an idle speed all over the shop. Took it off, quick blast through with aerosol carb cleaner, and it's rock solid.
 
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