Date: Fri, 23 Aug 2002 10:29:17 +0100
From: "Lee Marshall" <leenopsamvespamenigma-it.com>
Subject: Re: My dealer hasn't got a clue, can you help? ('97 9000 Aero, Manual)
Keith,
If you had said that the Pressure Transducer was also known as the MAP
sensor I would have known what you were talking about! According to County
Saab, they have already checked out the MAP sensor, at least that's what
they said when I asked them about it a few months ago. I will bring this up
with them again later today. Is there a chance that a fuel or waste deposit
could have blocked the nipple or hose to the MAP sensor?
You said that you assume that I have not driven another Aero that works
correctly. True, but I did drive mine whilst it worked correctly (I have had
the vehicle for 2 years).
One bit of confusion I do want to sort out is that I believe the problem
only happens when the engine is under load, I don't believe it is related to
the throttle position. My reasoning is that the problem never occurs in
first gear and very rarely in second, when there is little load on the
engine. However the problem is very prevalent in fifth and occurs often
before WOT. When the car is in third or fourth, it requires WOT to instigate
the problem (usually on a country road when you are trying to overtake a
line of slow moving traffic!!!).
Thanks for you help so far Keith!
Lee
"KeithG" <noonenopsamspring.com> wrote in message
news:3D64E32C.5010809nopsamspring.com...
> Lee,
>
> Still more musing on my part... If the MAP sensor lost a ground
> reference, I could imagine it exhibiting the symptom you describe. Why
> it does it only at WOT confuses it a bit. I am assuming that you have
> not driven another Aero which 'works correctly' to have a feel for it. I
> would disconnect the ECU and MAP and take a volt meter to verify that
> both the ECU and MAP get a low impedance connection to ground. If there
> is any variation, clean the bog engine ground cable at both ends and the
> ground connection for the FI system. It should be a single bolt with a
> number of ring connectors. To find this ground point, you'd have to have
> the electrical manual, guess, or ask the technician. It'll probably be
> near the battery or on the engine block somewhere. It COULD (very
> outside chance) be something INSIDE the short section of tubing or the
> nipple on the intake manifold which plugs the port and causes pressure
> to be under reported as well. If all these check out, swap in a known
> good MAP and see what it does. Please let us know what you learn as this
> is now bugging me.
>
> KeithG
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