Date: Tue, 07 May 2002 18:20:02 GMT
From: leenopsamamenigma-it.com (Lee Marshall)
Subject: Re: My dealer hasn't got a clue, can you help? ('97 9000 Aero, Manual)
On 7 May 2002 18:02:01 GMT, davehinznopsamcop.net wrote:
>
>Disclaimer: I don't know the inner workings of your particular control
>unit.
>
>However - as I understand it, and I'd be surprised to find that it has
>changed, the knock sensor is there specifically to let the system know
>when it's boost has gone so high as to cause predetonation (ping), and
>to back down on the boost from there. Look at it this way - your problem is
>that your boost is too high, right?
>
>The only way for boost to be controlled is by opening the wastegate,
>ultimately. If the wastegate isn't opening, it's either a problem
>with the wastegate itself (which has been changed), or with the parts
>that are supposed to be opening it. So, either the control module is
>telling it to open and something between it and the wastegate is bad
>(solenoid, right?), or the unit is bad, or the unit is getting bad
>input from a sensor which is supposed to modulate boost.
>
>I've been to that dealer in Milton Keynes, but it was about a decade ago.
>(the new 900 was just coming out, I found myself in England for a few
>months, and went in there to ask the sales guy to arrange a factory
>visit in Trollhatten). They seemed quite knowledgeable about the cars
>at the time, so I am a bit reluctant to second-guess them. However,
>it wouldn't hurt to ask if they've narrowed it down to a sensor, or
>a control problem. Either the box isn't getting the right information,
>or it is, and it's actions aren't being translated into opening of the
>wastegate. Until they can tell you which side of the box the problem
>is on, any fix will be by blind luck.
>
>> Thanks for your prompt reply, keep them coming!
>
>Please note previous disclaimer; my in-depth understanding of the
>Saab's boost strategies is based on the APC system which I believe
>predates your car. But, the principles remain...
>
>> Lee
>
>Dave Hinz
>
Thanks again Dave.
My car does have the APC system (it says so on the boost gauge), so
hopefully your information will be as helpful as it sounds.
They have not been able to narrow down the problem at all (you can
hear the service managers despair when I call), it could be anywhere.
As they have replaced all the parts that you have mentioned (control
module, solenoid etc) except the knock sensor I will call them first
thing in the morning to "suggest" it.
If you are correct do you have any idea on a price for a knock sensor?
I bet that it's a lot less than the £2000 they have already spent on
parts!!
The only good thing to come out of this so far is that I know my car
will have had a lot of expensive components replaced which may have
cost me a lot when the warranty expires.
I will let you know how I get on.
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